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Background and Objective: Amoxicillin-clavulanic acid (AX-CL) is the most consumed ß-lactam antibiotic worldwide. We aimed to establish the different phenotypes of ß-lactam allergy in patients reporting a reaction to AX-CL and to investigate the differences between immediate and nonimmediate onset., Methods: We performed a cross-sectional retrospective study at Hospital Clínico San Carlos (HCSC), Madrid and Hospital Regional Universitario de Málaga (HRUM), Málaga, Spain. We included patients reporting reactions with AX-CL who underwent the allergy workup between 2017 and 2019. Data on the reported reaction and allergy work-up were collected. Reactions were classified as immediate and nonimmediate with a 1-hour cut-off., Results: The study population comprised 372 patients (HCSC 208, HRUM 164). There were 90 immediate reactions (24.2%), 252 nonimmediate reactions (67.7%), and 30 reactions with unknown latency (8.1%). Allergy to ß-lactams was ruled out in 266 patients (71.5%) and confirmed in 106 patients (28.5%). The final main diagnosis in the overall population was allergy to aminopenicillins (7.3%), to CL (7%), to penicillin (6.5%), and to ß-lactams (5.9%). Allergy was confirmed in 77.2% and 14.3% of immediate and nonimmediate reactions, respectively, with a relative risk of 5.06 (95%CI, 3.64-7.02) for an allergy diagnosis in those reporting immediate reactions. Only 2/54 patients with a late-positive intradermal test (IDT) result for CL were diagnosed with CL allergy., Conclusion: Allergy was diagnosed in a minority of the study population. However, given that it was diagnosed 5 times more frequently in patients reporting immediate reactions, this classification proved useful for risk stratification. Late-positive IDT results for CL have no diagnostic value. Therefore, the late IDT reading for CL could be removed from the diagnostic work-up.

Background: Thiocolchicoside is a muscle relaxant, anti-inflammatory, and analgesic. Administered orally, intramuscularly, or topically, this drug is used in the symptomatic treatment of muscular spasms and rheumatologic disorders. Despite its extensive use, thiocolchicoside is a very rare sensitizer., Objective: To evaluate IgE-mediated reaction to thiocolchicoside by basophil activation test., Methods: Allergological work-up with skin prick tests, intradermal tests and basophil activation test with thiocolchicoside., Results: We report the first case of immediate reaction to thiocolchicoside confirmed by basophil activation test in addition to positive skin tests., Conclusions: BAT can be considered a complementary diagnostic tool to demonstrate an IgE-mediated reaction also for muscle relaxant drugs.

Immediate drug-induced hypersensitivity reactions (IDHSRs) have conventionally been attributed to an immunoglobulin E (IgE)-mediated mechanism. Nevertheless, it has now been acknowledged that IDHSRs can also occur independently of IgE involvement. Non-IgE-mediated IDHSRs encompass the activation of effector cells, both mast cell-dependent and -independent and the initiation of inflammatory pathways through immunogenic and nonimmunogenic mechanisms. The IDHSRs involve inflammatory mediators beyond histamine, including the platelet-activating factor, which activates multiple cell types, including smooth muscle, endothelium, and MC, and evidence supports its importance in IgE-mediated reactions in humans. Clinically, distinguishing IgE from non-IgE mechanisms is crucial for future treatment strategies, including drug(s) restriction, readministration approaches, and pretreatment considerations. However, this presents significant challenges because certain drugs can trigger both mechanisms, and their presentations can appear similarly, ranging from mild to life-threatening symptoms. Thus, history alone is often inadequate for differentiation, and skin tests lack a standardized approach. Moreover, drug-specific IgE immunoassays have favorable specificity but low sensitivity, and the usefulness of the basophil activation test remains debatable. Lastly, no biomarker reliably differentiates between both mechanisms. Whereas non-IgE-mediated mechanisms likely predominate in IDHSRs, reclassifying most drug-related IDHSRs as non-IgE-mediated, with suggested prevention through dose administration adjustments, is premature and risky. Therefore, continued research and validated diagnostic tests are crucial to improving our capacity to distinguish between these mechanisms, ultimately enhancing patient care., (Copyright © 2024 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Background: Carboplatin administration poses a risk of immediate hypersensitivity reactions (IHRs) that tend to increase with repeated administration and are mostly IgE-mediated., Objective: This study evaluated the usefulness of carboplatin-prescreening intradermal skin tests (IDTs)., Methods: Carboplatin-prescreening IDTs were routinely conducted in patients with a history of receiving six or more carboplatin cycles beginning in January 2021. The primary objective was to assess disparities in the incidence of unanticipated IHRs to carboplatin administration. We compared patients in the intervention group (from 2021 to 2022) and those who did not undergo prescreening IDTs under the same conditions (preintervention group, from 2019 to 2020). Secondary objectives included evaluating the sensitivity and specificity of the prescreening IDT and the incidence of carboplatin IHR according to the number of infusion cycles., Results: The intervention group was composed of 67 patients who were administered 347 carboplatin cycles whereas the preintervention group included 96 patients who were administered 464 carboplatin cycles. The risk of unanticipated carboplatin IHRs decreased by 83.2% in the intervention group compared with results in the preintervention group (preintervention group, 3.45%, n = 16 vs intervention group, 0.58%, n = 2; P = .005). The prescreening IDT showed a sensitivity and specificity of 77.78% and 99.41%, respectively. The risk of newly developed IHRs based on the number of carboplatin cycles was less than 1% (cycles 1-5), 2.11% (cycle 6), 3.90% (cycles 7-12), 2.90% (cycles 13-18), and 0.74% (cycles 19 and greater), respectively., Conclusions: Initiating carboplatin-prescreening IDTs from the seventh cycle on significantly reduced the risk of unanticipated IHRs., (Copyright © 2023 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Proton pump inhibitors (PPIs) are invaluable therapeutic options in a variety of dyspeptic diseases. In addition to their well-known risk profile, PPI consumption is related to food and environmental allergies, dysbiosis, osteoporosis, as well as immediate and delayed hypersensitivity reactions (HSRs). The latter, although a rare event, around 1%-3%, due to the extraordinarily high rate of prescription and consumption of PPIs are related to a substantial risk. In this Position Paper, we provide clinicians with practical evidence-based recommendations for the diagnosis and management of HSRs to PPIs. Furthermore, the unmet needs proposed in the document aim to stimulate more in-depth investigations in the topic., (© 2023 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Immediate drug hypersensitivity reactions (IDHRs) are a burden for patients and the health systems. This problem increases when taking into account that only a small proportion of patients initially labelled as allergic are finally confirmed after an allergological workup. The diverse nature of drugs involved will imply different interactions with the immunological system. Therefore, IDHRs can be produced by a wide array of mechanisms mediated by the drug interaction with specific antibodies or directly on effector target cells. These heterogeneous mechanisms imply an enhanced complexity for an accurate diagnosis and the identification of the phenotype and endotype at early stages of the reaction is of vital importance. Currently, several endophenotypic categories (type I IgE/non-IgE, cytokine release, Mast-related G-protein coupled receptor X2 (MRGPRX2) or Cyclooxygenase-1 (COX-1) inhibition and their associated biomarkers have been proposed. A precise knowledge of endotypes will permit to discriminate patients within the same phenotype, which is crucial in order to personalise diagnosis, future treatment and prevention to improve the patient's quality of life., (© 2023 The Authors. Allergy published by European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: Local anesthetic (LA) drugs are commonly used in clinical practice to provide effective analgesia, including in dentistry and minor surgical procedures. The perception of a high risk of allergy in daily applications leads to the referral of atopic patients and those with other drug allergies to allergy clinics for the evaluation of allergic reactions to LA. The aim of this study was to determine who should be referred to the allergy clinic for LA allergy testing, assess the frequency of LA allergy in pediatric patients, and identify the negative predictive value of skin tests in diagnosis., Methods: January 2017-July 2023, the clinical and laboratory data, as well as the results of drug allergy tests, of patients referred to our pediatric allergy clinic by dentists and physicians performing minor surgical procedures with suspected LA allergy were retrospectively evaluated., Results: Our study included a total of 153 patients, comprising 84 girls (54.9%) and 69 boys (45.1%), with a mean age of 8.9 (±3.3) years. The most common reason for referral was a history of non-LA drug allergies (n = 66, 43.2%), followed by asthma (n = 25, 16.3%). Hypersensitivity reactions (HRs) with LA were most commonly associated with articaine (n = 7, 4.8%), followed by lidocaine (n = 6, 4.1%). When intradermal tests were evaluated, 17 patients (11.1%) had a positive test result. The positivity for lidocaine was 70.6% (n = 12), and prilocaine was 29.4% (n = 5). Subcutaneous provocation was administered to 109 patients (71.2%), and one patient exhibited local erythema and swelling with prilocaine., Conclusion: Although LA allergy is a rare occurrence, consultations of this nature are frequently requested from allergy clinics in real life. Considering the negative predictive value of skin tests performed with LA drugs, the reaction rate appears to be low in patients with atopy or other drug allergies. It is crucial for all relevant healthcare professionals to be knowledgeable about the appropriate approach to suspected LA allergies to avoid unnecessary tests. To the best of our knowledge, our study is the most comprehensive work in the literature that evaluates the results of diagnostic tests in children referred with a suspicion of LA allergy., (© 2024 European Academy of Allergy and Clinical Immunology and John Wiley & Sons Ltd.)

Background: There is no accepted grading system classifying the severity of immediate reactions to drugs., Objective: The purpose of this article is to present a proposed grading system developed through the consensus of drug allergy experts from the United States Drug Allergy Registry (USDAR) Consortium., Methods: The USDAR investigators sought to develop a consensus severity grading system for immediate drug reactions that is applicable to clinical care and research., Results: The USDAR grading scale scores severity levels on a scale of 0 to 4. A grade of no reaction (NR) is used for patients who undergo challenge without any symptoms or signs, and it would confirm a negative challenge result. A grade 0 reaction is indicative of primarily subjective complaints that are commonly seen with both historical drug reactions and during drug challenges, and it would suggest a low likelihood of a true drug allergic reaction. Grades 1 to 4 meet the criteria for a positive challenge result and may be considered indicative of a drug allergy. Grade 1 reactions are suggestive of a potential immediate drug reaction with mild symptoms. Grade 2 reactions are more likely to be immediate drug reactions of moderate severity. Grade 3 reactions have features suggestive of a severe allergic reaction, whereas grade 4 reactions are life-threatening reactions such as anaphylactic shock and fatal anaphylaxis., Conclusion: This proposed grading schema for immediate drug reactions improves on prior schemata by being developed specifically for immediate drug reactions and being easy to implement in clinical and research practice., (Copyright © 2023 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: Serum tryptase, a mast cell marker, provides clues for the mechanism, severity, and management of drug hypersensitivity induced by immunoglobulin E dependent or independent mast cell activation., Recent Findings: The interpretation of serum tryptase levels has been challenged during the last 2 years by major advances in tryptase genetics and their rapid incorporation into clinical practice. On the contrary, new pathophysiological insight into nonmast cell-dependent immediate hypersensitivity has been gained., Summary: This review provides up-to-date information on the pathophysiology and recommended use and interpretation of tryptase in the context of drug hypersensitivity reactions as a function of their endotype., (Copyright © 2023 Wolters Kluwer Health, Inc. All rights reserved.)

Local anesthetics (LA) are commonly used in procedures and in topical agents for pain management. With the increasing use of LA drugs, the management of LA reactions is more frequently encountered in the office and in operating rooms. True allergic reactions involving IgE-mediated reactions and anaphylaxis are rare; they have only been identified in case reports and account for less than 1% of adverse LA reactions. Most reactions are non-allergic or are a result of hypersensitivity to other culprits such as preservatives, excipients, or other exposures. LA reactions that are misclassified as true allergies can lead to unnecessary avoidance of LA drugs or delays in surgical procedures that require their use. A detailed history of prior LA reactions is the first and most crucial step for understanding the nature of the reaction. Reactions that are suspicious for an immediate hypersensitivity reaction can be evaluated with skin prick and intradermal testing with subsequent graded challenge. Reactions that are suspicious for a delayed hypersensitivity reaction can be evaluated with patch testing., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Gadolinium based contrast agents (GBCAs) are safe compounds globally used in magnetic resonance imaging (MRI). However, in last years it has been detected an increase of immediate hypersensitivity reactions (IHRs) to them. Diagnosis of IHRs to GBCAs is based on clinical symptoms, skin tests (STs) and drug provocation test (DPT). But DPTs are not without risks, thus it is important to implement an in vitro alternative method such as the basophil activation test (BAT). We described the clinical validation of the BAT using ROC curves from a control population formed by 40 healthy individuals without previous reactions to any contrast agents and 5 patients suffering from IHRs to GBCAs. Four patients presented IHRs to gadoteric acid (GA) as the culprit agent and another one to gadobutrol (G). Basophil reactivity was measured in percentage of CD63 expression and in stimulation index (SI). The optimal cut-off with the highest sensitivity (S) and specificity (E) for the GA was of 4.6% at 1:100 dilution (S = 80% and E = 85%; AUC = 0.880, p = 0.006). For the SI with GA, the cut-off of highest sensitivity and specificity was of 2.79 at 1:100 dilution (S = 80% and E = 100%; AUC = 0.920, p = 0.002). Sensitivity did not show differences between STs regarding the BAT (p < 0.05). Moreover, the BAT was able to detect one case with IHR to GA which had negative STs. Therefore, the BAT is a useful method in diagnosis of IHRs to GBCAs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Chlorhexidine generally has a good safety profile. However, allergic reactions are reported with increasing frequency. In China, it is rarely reported, and its characteristics are unknown. The purpose of this study was to summarize the experience of a Chinese allergy center with chlorhexidine allergy., Methods: The authors retrospectively reviewed all patients who underwent chlorhexidine allergy testing in the Allergy Center of West China Hospital, Sichuan University (Chengdu, China), in the period February 2018 to May 2022 (n = 43 patients) and included the patients diagnosed with chlorhexidine allergy for analysis., Results: Ten patients who were diagnosed by skin prick and serum-specific immunoglobulin E tests were included. They experienced a total of 30 allergic reactions to chlorhexidine (mean ± SD, 3.0 ± 1.3). Five patients experienced six allergic reactions (6 of 30, 20%) during general or local anesthesia, and they may have been exposed to chlorhexidine via different routes. Only one allergic reaction (1 of 30, 3%) was recorded with exposure via a mouthwash. The other 23 allergic reactions (23 of 30, 77%) were caused via a skin disinfectant; the route of exposure was IV cannulation in 22 allergic reactions (22 of 23, 96%) and broken skin in one allergic reaction (1 of 23, 4%). The symptoms included a quick onset and great severity. Two patients (2 of 10, 20%) had been accidentally re-exposed to chlorhexidine after diagnosis., Conclusions: This study conducted in China showed that the majority of reactions to chlorhexidine were attributed to skin disinfectants, and IV cannulation was the most common exposure route; in general, however, chlorhexidine allergy was easily overlooked. The potential allergenicity of chlorhexidine used for skin preparation before IV cannulation or should be considered in patients who develop allergic reactions perioperatively., (Copyright © 2023, the American Society of Anesthesiologists. All Rights Reserved.)

Background: Corticosteroids, which are anti-inflammatory and immunosuppressive agents used for the treatment of various diseases including allergic disorders, can induce immediate and delayed hypersensitivity reactions. Although these reactions are not common, due to the wide usage of corticosteroid medications, corticosteroid hypersensitivity reactions are clinically important., Objective: In this review, we summarise the prevalence, pathogenetic mechanism, clinical manifestations, risk factors, diagnostic and therapeutic approach for corticosteroid-induced hypersensitivity reactions., Methods: An integrative review of the literature was conducted using PubMed searches (mainly large cohort-based studies) regarding the different aspects of corticosteroid hypersensitivity., Results: Hypersensitivity reactions to corticosteroids can be immediate or delayed and can follow all modes of corticosteroid administration. Prick and intradermal skin tests are useful diagnostic tools for immediate hypersensitivity reactions, patch tests are useful for delayed hypersensitivity reactions. According to the diagnostic tests an alternative (safe) corticosteroid agent should be administered., Conclusion: Physicians of all medical disciplines should be aware that corticosteroids can cause (paradoxically) immediate or delayed allergic hypersensitivity reactions. The diagnosis of such allergic reactions is challenging since it is often difficult to distinguish between hypersensitivity reactions and deterioration of the basic inflammatory disease (e.g., worsening of asthma or dermatitis). Thus, a high index of suspicion is needed in order to identify the culprit corticosteroid.

Immediate drug hypersensitivity reactions (DHRs) are historically thought to be because of immunoglobulin E (IgE) cross-linking, causing mast cell degranulation and release of mediators like tryptase and histamine. With the increasing use of monoclonal antibodies, it has become apparent that some patients present atypical features during immediate DHRs, including occurrence in initial exposure, a lack of urticaria and angioedema, and the presence of fever, chills, rigors and musculoskeletal pain as the predominant symptoms. This observation led to the recognition of a novel phenotype of immediate DHRs called cytokine release syndrome (CRS). Other types of immediate DHRs include infusion-related reactions (which present similarly to CRS), and mixed reactions (which share overlapping features of both type 1 reactions and CRS). Desensitization to culprit drugs can be a lifesaving option in patients who develop immediate DHRs to first-line treatment. Whereas robust data are supporting the safety and efficacy of drug desensitization, breakthrough reactions can still occur and CRS seems to be a more common cause than type 1 reactions. Tryptase has been the only available biomarker for immediate DHRs and is associated with type 1 reactions. Emerging evidence consistently found the association between increased serum interleukin 6 level and DHR-related CRS, suggesting that interleukin 6 can be a novel biomarker, in addition to tryptase, to distinguish various types of DHRs. In the era of precision medicine, phenotyping and endotyping hypersensitivity reactions to chemotherapy and monoclonal antibodies using validated biomarkers should be part of routine drug allergy care., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: In light of the pandemic of spurious penicillin allergy, correct diagnosis of amoxicillin (AX) allergy is of great importance. The diagnosis of immediate hypersensitivity reactions relies on skin tests and specific IgE, and although reliable, these are not absolutely predictive. Therefore, drug challenges are needed in some cases, which contain the risk of severe reactions. Safe in vitro diagnostics as an alternative for the drug challenge in the diagnostic workup of AX allergy would be more than welcome to fill this gap. In this respect, the basophil activation test (BAT) has shown potential, but its clinical reliability is doubtful., Objective: To investigate the reliability of the BAT to AX and determining its exact place in the diagnostic algorithm of AX allergy., Methods: BAT for AX was performed in 70 exposed control individuals and 66 patients diagnosed according to the European Academy of Allergy and Clinical Immunology guidelines for AX allergy. Upregulation of both CD63 and CD203c was flow-cytometrically assessed., Results: Analyses revealed that 1370 μmol/L and 685 μmol/L were the most discriminative stimulation concentrations for CD63 and CD203c upregulation, respectively, and a diagnostic threshold of 9% for positivity for both markers was identified. At these concentrations, sensitivity and specificity for CD63 upregulation were 13% and 100%, respectively, and for CD203c upregulation, 23% and 98%., Conclusions: BAT with dual analysis of CD63 and CD203c is of poor performance to document AX allergy. The sensitivity is too low to let it occupy a prominent role in the diagnostic algorithm., (Copyright © 2022. Published by Elsevier Inc.)

Introduction: Beta-lactam (BL) antibiotics are the most often involved drugs in allergic reactions. Mild cutaneous reactions such as maculopapular exanthema or urticaria are the most common presenting complaints of BL allergy in the pediatric population. However, it can be challenging to distinguish BL-induced allergy from reactions due to infections or other reasons. In this study, we aimed to determine the clinical characteristics and potential risk factors of true BL allergy in children with suspected mild cutaneous reactions to BLs., Methods: We evaluated children who were admitted to our pediatric allergy clinic with suspected BL allergy in between January 2015 and March 2020. Patients with a history suggestive of immediate and non-immediate mild cutaneous reactions were included in the study. The oral challenge test (OCT) with the culprit drug was performed on all patients to confirm the diagnosis., Results: Two hundred fourteen (119 male and 95 female) patients with a median age of 4.9 years were evaluated. BL allergy was confirmed in 10.7% (23) of the patients, according to the OCT results. Most of the proven allergic reactions were of the immediate type (73.9%), and urticaria was the most common presenting complaint (60.8%) in proven BL-allergic patients. The negative predictive value of penicillin-G skin testing was 89.7% for immediate-type penicillin allergy and 93.4% for non-immediate reactions. Also, positive predictive value of penicillin-G skin testing was 50% for immediate and 25% for non-immediate reactions. In the multivariate logistic regression analysis, a history of proven drug allergy (Exp (B): 7.76, 95% CI: 1.88-31.97, p = 0.005) was found to be the risk for BL allergy., Conclusion: This study highlighted that OCTs should be performed to confirm the diagnosis in patients suspected of immediate and non-immediate mild cutaneous reactions to BLs and remove the overestimated "BL allergy" label. In these patients, a history of proven drug allergy might be a risk factor for true BL allergy., (© 2023 S. Karger AG, Basel.)

Introduction: Ibuprofen is the most common culprit drug causing nonsteroidal anti-inflammatory drug (NSAID) hypersensitivity in children. We aimed to evaluate the frequency, clinical characteristics, and risk factors of confirmed ibuprofen allergy in children presenting with a history of suspected immediate type ibuprofen-induced hypersensitivity reactions., Methods: We evaluated 50 (35 M, 15 F) children with a median age of 7 years, who were referred to our clinic with suspected immediate ibuprofen hypersensitivity. Patients were subjected to a diagnostic work up including drug provocation tests (DPTs) with the culprit drug. Reactions were classified according to the European Academy of Allergy and Clinical Immunology Task Force recommendations for pediatric patients. Proven ibuprofen allergic patients underwent DPT to find a safe alternative drug., Results: Ibuprofen allergy was confirmed in 34% (n: 17) of children; 9 patients were diagnosed by DPTs and 8 patients diagnosed based on their histories. Angioedema was the most common clinical manifestation (n: 30, 60%). Among patients with proven ibuprofen allergy, 7 of them were classified as cross-intolerant. Cross-intolerance reactions were further classified as NSAID-exacerbated cutaneous disease (n = 1) and NSAID-induced urticaria/angioedema/anaphylaxis (n = 6). As an alternative drug, paracetamol was safely tolerated, whereas 1 patient developed angioedema and urticaria with nimesulide. Older age and male gender were identified as independent risk factors for immediate-type ibuprofen allergy., Conclusion: DPTs should be performed to confirm or exclude ibuprofen allergy in children and to find safe alternative drugs. Male gender and older age are risk factors for ibuprofen allergy. NSAID-induced hypersensitivity reactions in the pediatric population cannot be well defined using the adult classification system., (© 2022 The Author(s). Published by S. Karger AG, Basel.)

Background: Data on beta-lactam hypersensitivity (BLH) are mainly focused on immediate or mild nonimmediate reactions in the ambulatory setting, but limited in patients with concurrent illness and moderate-to-severe nonimmediate reactions in the hospitalized setting., Objective: To investigate the entire spectrum of BLH in Thai tertiary hospital., Methods: Clinical characteristics of 357 patients with suspected BLH were evaluated in a 7-year period. Culprit drug identification was performed in 335 patients by combined skin testing, in vitro testing, or drug provocation tests., Results: The predominant BLH presentations were non-immunoglobulin (Ig)E-mediated reactions with severe cutaneous adverse reactions of 18.9%, and BLH status was definitively confirmed in 18.1%. The most common verified culprits were cephalosporins (34.8%), particularly in hypersensitivity type IV reactions. Natural penicillins were the main implicated drugs in 48.5% of ambulatory patients. In contrast, cephalosporins and carbapenems were the main implicated drugs in hospitalized patients. Non-IgE-mediated anaphylaxis and serum sickness-like reaction remained diagnostically challenged. New generations of beta-lactams, hospitalized patients, recent allergic history, and underlying malignancies or autoimmune diseases were associated with increased BLH risk., Conclusion: At present, cephalosporins are the leading causes of BLH, particularly in non-IgE-mediated reactions. More research on the verification of non-IgE hypersensitivity reactions from new generations of beta-lactams should be better emphasized., Clinical Trial Registration: The registry was approved by the Ethics and Research Committee of the Faculty of Medicine, Chulalongkorn University, and listed on ClinicalTrials.gov (Identifier: NCT01667055; https://www., Clinicaltrials: gov/ct2/show/NCT01667055)., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Drug hypersensitivity is increasing worldwide as the consumption of drug is increasing. Many clinical presentations of drug hypersensitivity are complex and take place in the setting of illness and/or polypharmacotherapy. To review the most recent findings in the diagnosis and management of immediate drug hypersensitivity reactions. Studies were selected based on their relevance, originality and date of publication. The understanding of endotypes, biomarkers and phenotypes has improved the categorization of immediate hypersensitivity reactions. In this review, we discussed the short- and long-term management of anaphylaxis with a special focus on in vivo and in vitro diagnostic methods. Moreover, the clinical management of drug-induced anaphylaxis, the role of hidden allergens and the importance of delabeling are discussed. Endophenotyping is crucial to correctly diagnose and treat patients with immediate drug hypersensitivity reactions, preventing future episodes through drug desensitization., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Background: Immediate hypersensitivity reactions to penicillins are often labeled on the basis of a similar set of symptoms, but a key feature of these reactions that can be reproduced in diagnostic testing may be the timing of a reaction in relation to the dose administration., Objective: To determine whether the timing of a reaction in response to the last dose of a penicillin would predict the results of diagnostic testing., Methods: We evaluated 1074 patients by performing skin tests, serum specific IgE assays (ImmunoCAP), and challenges. Patients who were evaluated by us more than 6 months after their reactions and found negative were reevaluated within 2 to 4 weeks., Results: Patients who had reacted within 1 hour after the first dose, within 1 hour after subsequent doses, more than 1 hour to within 6 hours after the first dose, or more than 1 hour to within 6 hours after subsequent doses were classified as group A (758 individuals), B (92), C (67), or D (157), respectively. Penicillin hypersensitivity was diagnosed in 707 patients (65.8%) by skin tests (407 patients, 57.6%), ImmunoCAP (47, 6.6%), both tests (232, 32.8%), or challenges (21, 3%). A conversion to allergy-test positivity occurred in 7 of 10 patients with anaphylactic reactions and in 1 of 28 patients with other reactions who were reevaluated after negative challenges. The rate of penicillin-allergic patients in groups A, B, C, and D was 85%, 35.9%, 35.8%, and 3.8%, respectively. Only 1 of 107 patients reporting cutaneous reactions lasting more than 1 day had positive results to allergy tests., Conclusions: IgE-mediated hypersensitivity can be diagnosed by skin tests in about 70% of subjects who react within 1 hour (eg, patients from groups A and B). This hypersensitivity can be lost over time, as demonstrated by the negativization of allergy tests in follow-up studies. In subjects with anaphylactic reactions, however, it is advisable to not consider this phenomenon definitive. In fact, a conversion to allergy test positivity can be observed in up to 20% of such subjects retested after negative challenges., (Copyright © 2022 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Following intravenous contrast medium (CM) injection, a small proportion of patients acquires hypersensitivity reactions that occur either immediately or non-immediately (delayed). Although it is now claer that even oral applied CMs are able to cause adverse reactions, many radiologists as well as physicians of other disciplines, still believe that CM-application via the gastrointestinal route does not induce hypersensitivity reactions. Since this kind of misinterpretation may harm the patient, education on this topic is still necessary. Therefore, we describe a case who acquired a delayed hypersensitivity reaction following the oral intake of a non-ionic iodinated CM.

Diagnosis of type I hypersensitivity reactions (IgE-mediated reactions) to penicillins is based on clinical history, skin tests (STs), and drug provocation tests (DPTs). Among in vitro complementary tests, the fluoro-enzyme immunoassay (FEIA) ImmunoCAP ® (Thermo-Fisher, Waltham, MA, USA) is the most widely used commercial method for detecting drug-specific IgE (sIgE). In this study, we aimed to analyze the utility of ImmunoCAP ® for detecting sIgE to penicillin G (PG) and amoxicillin (AX) in patients with confirmed penicillin allergy. The study includes 139 and 250 patients evaluated in Spain and Italy, respectively. All had experienced type I hypersensitivity reactions to penicillins confirmed by positive STs. Additionally, selective or cross-reactive reactions were confirmed by DPTs in a subgroup of patients for further analysis. Positive ImmunoCAP ® results were 39.6% for PG and/or AX in Spanish subjects and 52.4% in Italian subjects. When only PG or AX sIgE where analyzed, the percentages were 15.1% and 30.4%, respectively, in Spanish patients; and 38.9% and 46% in Italian ones. The analysis of positive STs showed a statistically significant higher percentage of positive STs to PG determinants in Italian patients. False-positive results to PG (16%) were detected in selective AX patients with confirmed PG tolerance. Low and variable sensitivity values observed in a well-defined population with confirmed allergy diagnosis, as well as false-positive results to PG, suggest that ImmunoCAP ® is a diagnostic tool with relevant limitations in the evaluation of subjects with type I hypersensitivity reactions to penicillins.

In evaluating adverse drug reactions (ADRs), patch tests (PTs), skin prick tests (SPTs), and intradermal tests (IDTs) are useful tools for identifying responsible drugs and finding safe alternatives. Their diagnostic value depends on the clinical features of the ADR and on the drug tested. PTs have a good sensitivity in assessing acute generalized exanthematous pustulosis and drug rash with eosinophilia and systemic symptoms. SPTs done with all drugs except opiates are used for immediate hypersensitivity reactions. IDTs seem sensitive for immediate hypersensitivity reactions to beta-lactam antibiotics, iodinated contrast media, heparins, general anesthetics, and platinum salts., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Cefazolin is a common trigger of perioperative anaphylaxis. The diagnostic approach is controversial because the optimal concentration for skin testing is uncertain, drug provocation tests (DPTs) are contraindicated in severe reactions, and in vitro tests are not thoroughly validated., Objective: We aimed to characterize a large number of patients reporting cefazolin allergic reactions and to analyze the diagnostic role of in vivo and in vitro tests., Methods: We prospectively evaluated patients with suspicion for allergic reactions to cefazolin by clinical history, skin tests (STs), and, if negative, DPT. In a subgroup of patients, basophil activation test (BAT) and radioallergosorbent test were done before allergologic workup was performed and the final diagnosis was achieved., Results: We evaluated 184 patients, 76 of whom were confirmed as allergic (41.3%), 90 were nonallergic (48.9%), and 18 were nonconfirmed (9.8%). All patients reporting anaphylactic shock and most reporting anaphylaxis were confirmed to be allergic (P < .001). Forty allergic patients (52.6%) were confirmed by STs, 22 by DPT (28.9%), and 14 by clinical history (18.4%). All subjects manifesting exanthemas and pruritus were nonallergic. The BAT sensitivity was 66.7% when CD63 and CD203c were combined as activation markers. Six of 8 patients with negative STs and positive DPT had a positive BAT., Conclusions: Patients allergic to cefazolin often reported severe immediate-type reactions. Skin tests enabled a diagnosis in half of patients when using cefazolin at 20 mg/mL. Unfortunately, DPT could not be performed in all patients owing to reaction severity, which makes BAT a promising diagnostic tool. Further research is needed to clarify the underlying mechanisms, especially in severe reactions., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

The diagnosis of a drug hypersensitivity reaction (DHR) is complex. The first step after taking the clinical history is to look for a sensitization to confirm or exclude the diagnosis and to identify the culprit drug. Skin tests are the primary means of detecting sensitization in DHR, but are associated with a risk for a severe reaction and may be contraindicated. In vitro tests offer the potential to support or confirm a diagnosis of DHR and influence medical decision making. For immediate-type DHR, a few validated assays for measurement of specific IgE (sIgE) are commercially available to a limited number of drugs. In addition, several home-made sIgE radioimmunoassays have been used in other studies. The sensitivity of the sIgE assay is drug-dependant and generally low (0-85%) for betalactams and reported heterogeneous for other drugs ranging from 26% for chlorhexidine and 44% for suxamethonium to 92% for chlorhexidine. However, as all these studies included patients, in whom DHR was confirmed only by skin tests and not by provocation, the results have to be interpreted carefully and may be unreliable. Determination of mediators during an acute phase of a reaction may indirectly support the diagnosis of a DHR by demonstrating mast cell and basophil mediator release. Negative in vitro tests do not exclude a DHR or imputability of a drug, but a positive result may support causality and eliminate the necessity for a drug provocation test. Unfortunately, evidence is limited with a lack of well-controlled studies in larger numbers of well-phenotyped patients, which results in susceptibility for bias and a need for future multicenter studies., (Copyright © 2021. Published by Elsevier B.V.)

Background: Approximately 10% of the parents report suspected drug hypersensitivity reactions to at least one drug in their children, but most of these reactions are not confirmed after an adequate diagnostic work-up. The diagnosis of drugs hypersensitivity is frequently laborious and based on anamnesis, skin tests, serum specific IgE research and drug provocation test. Nevertheless, drug provocation test is necessary to confirm or definitively exclude the diagnosis of allergy. Aims of our study were to evaluate the real incidence of drug hypersensitivity in a large pediatric population and the validity of a short diagnostic algorithm., Methods: One hundred nine patients with a history of self-reported, immediate and mild drug hypersensitivity reactions to β-lactam antibiotics, macrolides and non-steroidal anti-inflammatory drugs underwent drug provocation test without prior skin or blood tests. After one-year, a telephone questionnaire was conducted in order to evaluate patient's use of the tested drug and any reactions., Results: Only 7 of the 109 patients (6.4%) resulted positive to drug provocation test. No severe reactions were reported. After the challenge, 64 patients took the culprit drug again within one year and only two reported a drug reaction., Conclusions: Drug hypersensitivity is highly overestimated. Our results prompt the opportunity to directly perform the challenge for those children with self-reported, mild and immediate drug hypersensitivity reaction.

Background/objectives: Adverse reactions to local anesthetics are relatively common, but proven IgE-mediated allergy is extremely rare. We aimed to determine the frequency of local anesthetic allergy in pediatric patients., Patients and Methods: The medical records of 73 patients who presented to our clinic with a history of suspected allergic reaction to local anesthetics and underwent diagnostic testing between 2012 and 2020 were retrospectively analyzed. Diagnoses were based on case histories, skin tests, and subcutaneous challenge tests., Results: A total of 75 test series were carried out on the 73 patients (43 boys; median [IQR] age 9.25 [7.26-14.25] years, range 3-17.8 years). The most commonly tested drugs were lidocaine (n = 38; 50.6%) and prilocaine (n = 15; 20%). Local anesthetic allergy was confirmed in one (1.3%) of the 73 patients by positive subcutaneous challenge test with mepivacaine., Conclusion: There are limited data in the current literature regarding local anesthetic allergies and diagnosis test results in pediatric patients. Proven local anesthetic allergy is less common than expected by society and physicians, and therefore diagnostic tests are needed for patients with no contra-indications such as severe or life-threatening reactions.

Immediate and nonimmediate hypersensitivity reactions to iodinated contrast media (ICM) have been reported to occur in a frequency of about 0.5%-3% of patients receiving nonionic ICM. The diagnosis and management of these patients vary among guidelines published by various national and international scientific societies, with recommendations ranging from avoidance or premedication to drug provocation test. This position paper aims to give recommendations for the management of patients with ICM hypersensitivity reactions and analyze controversies in this area. Skin tests are recommended as the initial step for diagnosing patients with immediate and nonimmediate hypersensitivity reactions; besides, they may also help guide on tolerability of alternatives. Re-exposition or drug provocation test should only be done with skin test-negative ICMs. The decision for performing either re-exposition or drug provocation test needs to be taken based on a risk-benefit analysis. The role of in vitro tests for diagnosis and pretreatment for preventing reactions remains controversial., (© 2020 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

Up to 10% of hospitalized patients have an antibiotic allergy label in their medical file, most frequently concerning penicillins. However, the vast majority of reported allergies to antibiotics does not represent a "true" allergy but are due to drug intolerance, idiosyncratic reactions or symptoms of the concurrent infectious disease. Since antibiotic allergy labels result in deviation from first-choice antimicrobial therapy, tackling the issue of incorrect antibiotic allergy labelling, already at young age, is a core element of antibiotic stewardship. In this article, we describe the structured approach to the patient with a presumed antibiotic allergy with emphasis on key elements of allergy-specific history taking and the limited risk of cross-allergic reactions between beta-lactam subclasses., Competing Interests: The authors have no funding or conflicts of interest to disclose., (Copyright © 2021 Wolters Kluwer Health, Inc. All rights reserved.)

Background: Piperacillin/tazobactam is a broad-spectrum penicillin. Hypersensitivity reactions are less commonly reported than with other penicillins except in patients with cystic fibrosis., Objective: Detailed clinical characterization of a patient cohort referred with suspected piperacillin-tazobactam hypersensitivity., Methods: Retrospective analysis of the demographic characteristics, clinical presentation, investigation, and management of 87 patients presenting to 5 European allergy centers. Patients underwent skin prick and intradermal testing with piperacillin/tazobactam, major (penicilloyl-polylysine) and minor (sodium penilloate) determinants, amoxicillin, benzylpenicillin, flucloxacillin, co-amoxiclav, clavulanic acid, and meropenem with immediate and, where appropriate, delayed reading of tests. Skin test-negative patients underwent drug provocation to piperacillin/tazobactam and/or other penicillins. A multistep protocol was used, depending on risk assessment., Results: Forty-eight of 87 (55%) patients were diagnosed with hypersensitivity to piperacillin/tazobactam with either positive skin or drug provocation test results, of whom 10 (21%) had a diagnosis of cystic fibrosis. Twenty-six (54%) patients presented with immediate and 22 (45%) with nonimmediate hypersensitivity. Patients with cystic fibrosis predominantly presented with nonimmediate hypersensitivity (70%). Reactions were severe in 52% of immediate reactors (Brown's anaphylaxis grade 3) and moderately severe (systemic involvement) in 75% of nonimmediate reactors. The number of patients with negative skin test results tolerating reintroduction was comparable in immediate (80%) and nonimmediate (88%) hypersensitivity. One-third of patients were cross-sensitized to other penicillins. The cross-sensitization pattern raised the possibility of tazobactam allergy in 3 patients. In 21 patients selectively sensitized to piperacillin/tazobactam (12 immediate, 9 nonimmediate), tolerance to other beta-lactams was demonstrated by drug provocation testing., Conclusions: Piperacillin-tazobactam caused immediate and nonimmediate hypersensitivity with similar frequency. Most patients were selectively sensitized and tolerated other penicillins. Some patients may be allergic to the beta-lactamase inhibitor only., (Copyright © 2021 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Ophthalmic quinolone preparations are widely used for the treatment of eye diseases; however, there are only a few reported cases of immediate hypersensitivity due to such medications. Here, we present a case of immediate hypersensitivity induced by an ophthalmic administration of quinolones in a 20-year-old female with bacterial conjunctivitis. The results of skin prick and basophil activation tests suggest that it involved a type Ib reaction associated with Mas-related G-protein coupled receptor X2. The present case cautions us to be aware of quinolone immediate hypersensitivity caused by topical ophthalmic preparations, which can easily be overlooked, because it may predict severe hypersensitivity reactions to systemic administration., (© 2020 Japanese Dermatological Association.)

Background: Little is known about the diagnostic approaches for immediate hypersensitivity reactions (IHRs) due to 5-nitroimidazole antibiotics. The aim was to evaluate the usefulness of in vivo tests and basophil activation test (BAT) for the diagnosis of IHRs due to metronidazole and ornidazole and to determine possible cross-reactivity in between., Methods: Forty-nine patients with a clear history of IHRs due to these drugs and 20 healthy subjects who were known to tolerate these drugs were included. Skin tests (STs) and single-blind placebo-controlled drug provocation tests (SBPCDPTs) were performed with both drugs whereas BAT was applied only with the culprit drug., Results: The most and least common reaction types were urticaria/angioedema (34.7%) and anaphylaxis (14.3%), respectively. SBPCDPTs were positive in 15 out of 47 patients, and only 7 had positive STs. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of STs for metronidazole/ornidazole were 33.3%/16.6%, 94.2%/97.3%, 60%/50%, and 84.6%/88.1%, respectively. BAT was positive in 12 out of 15 patients and negative in 10 control subjects, giving a sensitivity rate of 71.4% (CI, 29.0%-96.3%) for metronidazole and 83.3% (CI, 35.8%-99.5%) for ornidazole. The optimal concentration of both drugs for BAT was determined as 5 mg/mL. No cross-reactivity among two drugs was observed according to in vivo tests., Conclusions: Our study showed that SBPCDPT and BAT are both useful diagnostic tools for IHRs due to 5-nitroimidazole antibiotics and can be used as supplementary to each other. No cross-reactivity between metronidazole and ornidazole in IHRs exists., (© 2020 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

Background: Immediate drug hypersensitivity reactions are an increasing public health issue and a frequent cause of life-threatening anaphylaxis. Conventional confirmatory testing include skin tests and, for a few drugs, quantification of drug-specific immunoglobulin E (IgE) antibodies. However, none of these tests are absolutely predictive for the clinical outcome, and can yield false-negative and false-positive results. We performed a proof-of-concept study to assess whether a mast cell activation test could improve diagnosis of IgE-mediated chlorhexidine hypersensitivity, a common cause of perioperative anaphylaxis., Methods: Human mast cells were generated from CD34 + progenitor cells and sensitised with patients' sera to become IgE+ human mast cells (dMC IgE+ ), and then incubated with chlorhexidine to assess degranulation. We compared the diagnostic performance of this mast cell activation test with serum from patients with and without positive skin test and basophil activation test to chlorhexidine., Results: In dMC sensitised with sera from patients with a positive skin test and basophil activation test to chlorhexidine showed drug-specific and concentration-dependent degranulation upon stimulation with chlorhexidine, determined by surface upregulation of the degranulation marker CD63. In contrast, dMC sensitised with sera from patients with a negative skin test and basophil activation test to chlorhexidine were unresponsive in the mast cell activation test., Conclusions: Our study suggests that the mast cell activation test can be used to diagnose IgE/FcεRI-dependent immediate drug hypersensitivity reactions. It also shows potential to assess the clinical relevance of drug-specific IgE antibodies in their ability to elicit mast cell degranulation, and therefore discriminate between allergy and sensitisation. Extended studies are required to verify whether this technique can be used in other causes of perioperative anaphylaxis., (Copyright © 2020 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Background: Eperisone is a commonly prescribed oral muscle relaxant, but few studies have been conducted of eperisone-induced hypersensitivity reactions., Objective: The purpose of this study was to investigate the clinical manifestations of eperisone-induced immediate-type hypersensitivity, and to evaluate the role of an intradermal test (IDT) in eperisone-induced anaphylaxis., Methods: This study was based on a retrospective review of medical records from 23 patients diagnosed as eperisone-induced immediate-type hypersensitivity with certain or probable causality. Intradermal tests were performed with a sterile 10 mg/mL eperisone solution., Results: Immediate-type hypersensitivity reactions to eperisone occurred within 15 minutes in 8.7%, within 30 minutes in 52.2%, and within 60 minutes in 82.6% of the patients, cumulatively. All patients showed cutaneous symptoms. Gastrointestinal symptoms were the second-most frequent (65.2%), respiratory symptoms (56.5%) followed, and cardiovascular symptoms were the least (39.1%). Nine (39.1%) patients were categorized as severe anaphylaxis. The mean onset time of severe anaphylaxis was 28.89 minutes, which was significantly shorter than non-severe anaphylaxis (p = 0.011). Five patients among the severe anaphylaxis group were evaluated with IDT, and all showed positive results. In contrast, all of the four patients who have done IDT among the moderate anaphylaxis group showed negative results. There was a significant relationship between severe anaphylaxis and positive IDT results (p = 0.008)., Conclusions: Eperisone-induced immediate-type hypersensitivity is not uncommon in Korea, and the IDT could be a useful and safe diagnostic tool, especially in severe anaphylaxis.

Background: The first-line method in the diagnosis of patients who describe an immediate reaction after penicillin intake is a skin test (ST) with penicillin reagents. Objectives: We aimed to determine the safety and diagnostic value of penicillin STs in the diagnosis of immediate reactions to penicillins in pediatric patients. Methods: The study included pediatric patients with suspected immediate reaction to penicillin who were subjected to STs by using a standard penicillin test kit as well as suspected penicillin and the drug provocation tests (DPT) with the suspected penicillin at our clinic. Results: A total of 191 patients (53.9% boys) with a median age of 6.83 years (interquartile range, 4.2-12 years) were included in the study. The time from drug intake to the onset of reaction was ≤1 hour in 138 patients (72.3%) and 1 to 6 hours in 53 patients (27.7%). Penicillin allergy (PA) was confirmed by diagnostic tests in 36 of the 191 patients (18.8%). In multivariate logistic regression analysis, the history of both urticaria and angioedema (odds ratio [OR] 27.683 [95% confidence interval {CI}, 3.143-243.837]; p = 0.003) and anaphylaxis (OR 56.246 [95% CI, 6.598-479.489]; p < 0.001) were the main predictors of a PA diagnosis. Although ST results were positive in 23 patients (63.8%), 13 patients (26.2%) had positive DPT results despite negative ST results. The negative predictive value (NPV) of STs was calculated 92.2% (155/168). None of our patients experienced immediate or delayed systemic and/or local reactions in relation to the STs. Conclusion: A history of urticaria with angioedema and anaphylaxis were the main predictors of true PA in children with suspected immediate reactions. STs with penicillin reagents are safe for use in children. Although STs have a high NPV, DPT is the gold standard for diagnosis. DPTs should be performed as the final step of the diagnostic evaluation of PA in patients with negative ST results.

Background: Betalactam (BL) antibiotics are the most common cause of drug hypersensitivity. Amoxicillin (AX), which is often prescribed alongside clavulanic acid (Clav), is the most common elicitor. The aim of this study was to determine whether AX and Clav-responsive T-cells are detectable in patients with immediate hypersensitivity to AX-Clav, to assess whether these T-cells display the same specificity as that detected in skin and provocation testing, and to explore T-cell activation pathways., Methods: Drug-specific T-cell clones were generated from immediate hypersensitive patients´ blood by serial dilution and repetitive mitogen stimulation. Antigen specificity was assessed by measurement of proliferation and cytokine release. CD4 + /CD8 + phenotype and chemokine receptor expression were analyzed by flow cytometry., Results: 110 AX-specific and 96 Clav-specific T-cell clones were generated from seven patients with positive skin test to either AX or Clav. Proliferation of AX- and Clav-specific clones was dose-dependent, and no cross-reactivity was observed. AX- and Clav-specific clones required antigen-presenting cells to proliferate, and drugs were presented to CD4 + and CD8 + T-cells by MHC class-II and I, respectively. A higher secretion of IL-13 and IL-5 was detected in presence of the culprit drug compared with the alternative drug. Clones expressed CD69, CCR4, CXCR3, and CCR10., Conclusions: Our study details the antigen specificity and phenotype of T-cell clones generated from patients with AX-Clav-induced immediate hypersensitivity diagnosed by positive skin test. AX- and Clav-specific clones were generated from patients irrespective of whether AX or Clav was the culprit, although differences in cytokine secretion were observed., (© 2020 EAACI and John Wiley and Sons A/S. Published by John Wiley and Sons Ltd.)

Background: Quinolones are the second most frequent cause of hypersensitivity reactions (HSRs) to antibiotics. A marked increase in the number of patients with HSRs to quinolones has been detected., Objective: To describe the clinical characteristics of patients with HSRs to quinolones and present methods for their diagnosis., Methods: Patients attending the allergy unit due to reactions suggestive of HSRs to quinolones were prospectively evaluated between 2005 and 2018. Diagnosis was achieved using clinical history, skin tests (STs), basophil activation tests (BATs), and drug provocation tests (DPTs) if ST and BAT results were negative., Results: We included 128 subjects confirmed as having HSRs to quinolones and 42 found to be tolerant. Anaphylaxis was the most frequent entity in immediate HSRs and was most commonly induced by moxifloxacin. Patients were evaluated a median of 150 days (interquartile range, 60-365 days) after the reaction. Of patients who underwent ST and BAT, 40.7% and 70%, respectively, were positive. DPT with a quinolone was performed in 48 cases, giving results depending on the culprit drug: when moxifloxacin was involved, 62.5% of patients gave a positive DPT result to ciprofloxacin, whereas none reacted to levofloxacin. The risk of HSR was 96 times higher in subjects who reported moxifloxacin-induced anaphylaxis and 18 times higher in those reporting immediate reactions compared with clinical entities induced by quinolones other than moxifloxacin and nonimmediate reactions., Conclusions: The diagnosis of HSR to quinolones is complex. The use of clinical history is essential as a first step. BAT shows higher sensitivity than STs. DPTs can be useful for finding safe alternative quinolones., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Purpose of Review: Although rare and counterintuitive, hypersensitivity reactions to corticosteroids have been reported since the 1950s. Delayed hypersensitivity reactions following cutaneous exposure (contact allergy) are well understood and principles of testing, as well as cross-reactivity patterns, have been established. In contrast, understanding of immediate hypersensitivity reactions and delayed hypersensitivity reactions after systemic exposure is evolving more slowly. However, progress has been made in the delineating of underlying pathogenic mechanisms and in the development of testing., Recent Findings: IgE-mediated hypersensitivity reactions to corticosteroids have been described. It has been recognized that some, if not all of them, may be due to excipients in steroid formulations. Two excipients, polyethylene glycol and carboxymethylcellulose, seem of particular importance, but cases of reactions to polysorbate 80 and lactose have also been reported. The use of skin testing but also, increasingly, in-vitro methods such as basophil activation test is improving diagnostic accuracy., Summary: The recognition of the role of excipients is leading to a paradigm shift in our approach to immediate hypersensitivity to corticosteroids. Improved access to in-vivo and in-vitro testing will enhance our understanding of true corticosteroid immediate allergy.

Objective: To review novel concepts in drug hypersensitivity and the management of immediate hypersensitivity reactions., Data Sources: English language literature on MEDLINE and Embase surrounding drug hypersensitivity and desensitization., Study Selections: References were selected based on relevance, date of publication, and originality., Results: There are numerous citations looking at categorizing drug reactions, pathogenesis, biomarkers, and desensitization. Current understanding supports the use of a phenotype-endotype-biomarker model for categorizing immediate hypersensitivity reactions. Drug desensitization is a powerful therapeutic strategy that enables temporary induction of tolerance to medications that triggered immediate reactions., Conclusion: Immediate hypersensitivity reactions are diverse in presentation and pathogenesis. Drug desensitization is an effective intervention with sufficient evidence to support its more widespread availability., (Copyright © 2020. Published by Elsevier Inc.)