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Background Chronic itch is difficult to treat. Low-concentration topical capsaicin (0·006–0·05%) has previously been applied in itch therapy but evidence on its efficacy is contradictory. Objectives This vehicle-controlled, double-blinded study investigated the effect of topical capsaicin 8% after 1- and 24-h application on evoked itch, neurogenic inflammation and itch-associated dysaesthesia. Methods Sixteen healthy volunteers (aged 22 ± 0·5 years, nine female) were treated with capsaicin for 1 h and 24 h, and vehicle for 24 h on each volar forearm. Subsequently, histamine (1%, administered prick test lancets) and cowhage (40–45 spicules) were applied to the pretreated areas. Evoked itch and pain intensities were recorded for 10 min using a visual analogue scale (0–10 cm), while sensitivity to touch-evoked itch was evaluated using von Frey filaments before and after itch provocations. Neurogenic inflammation was assessed using perfusion imaging. Results In the vehicle areas peak itch responses to histamine and cowhage were 4·67 ± 0·58 and 5·15 ± 0·71, respectively. Capsaicin pretreatment reduced peak itch responses to histamine and cowhage after 24-h pretreatment to 1·41 ± 0·58 (P = 0·003) and 0·81 ± 0·18, (P < 0·001), respectively. Capsaicin pretreatment for 1 h reduced only cowhage-induced itch (P = 0·023). Furthermore, 24-h capsaicin pretreatment abolished punctuate hyperknesis and lowered histamine-induced neurogenic inflammation but did not affect weal reactions. Conclusions Topical capsaicin 8% pretreatment for 24 h reduced histaminergic and nonhistaminergic itch by about 75%, while a significant reduction (≈60%) was achieved for only nonhistaminergic itch in a standard 1-h treatment. Further investigations are needed to elucidate the clinical potential of high-concentration capsaicin as an antipruritic. [ABSTRACT FROM AUTHOR]

The article offers information on the use of topical capsaicin for the treatment of neuropathic itch conditions. Topics discussed includes effect on the cytoskeletal structure of the involved terminal branches, cases of notalgia paraesthica without hyperpigmentation, and antipruritic efficacy of randomized controlled trial for the treatment.

Background  Hand eczema is a common disease with a wide severity spectrum. Little information exists concerning the association between the severity of hand eczema and medical consultations. Objectives  To describe the self-rated severity of hand eczema in a general population and the relationship to seeking medical attention. Methods  A questionnaire on self-reported hypersensitivity including two questions on hand eczema was sent to a random sample of 6000 individuals, aged 18–69 years, living in Copenhagen, Denmark. A total of 4242 individuals (71%) answered the questionnaire. All individuals who reported hand eczema ( n = 752) within the previous 12 months received a more detailed questionnaire focused on hand eczema and a previously validated photographic guide with four groups of severity ranging from almost clear to very severe. Results  Five hundred and sixty-four individuals (75%) returned the second questionnaire. The 1-year period prevalence of hand eczema was estimated to be 14% in the population. Twenty-three per cent rated their hand eczema as moderate to very severe. In total, 67% had consulted their general practitioner and 44% had consulted a dermatologist because of hand eczema. Multivariate analysis showed a positive association ( P < 0·05) between severity of hand eczema and medical consultations. Of those individuals ( n = 102) who had not consulted a dermatologist 26% had experienced moderate to very severe hand eczema within the previous 12 months. Conclusions  A considerable proportion of individuals with moderate to very severe hand eczema in the general population miss out on the potential benefit of a dermatological examination, patch testing and a thoroughgoing exploration of environmental factors. [ABSTRACT FROM AUTHOR]

Exposure to volatile fragrances is commonplace and may be related to various eye and airway symptoms. Skin exposure to fragrances is known to cause perfume contact allergy and eczema, but it is unknown whether eye or airway symptoms elicited by fragrance products are associated with contact allergy or eczema.To investigate if eye and airway symptoms elicited by fragrance products are associated with perfume contact allergy or hand eczema in a population-based sample.A questionnaire on eye and airway symptoms elicited by fragrance products was mailed to 1189 individuals who had recently participated in a Danish population-based study of allergic diseases. Results from the questionnaire about localization and character of the symptoms were compared with data on patch testing and 1-year prevalence of hand eczema collected during the health examination.Positive, independent and significant (P < 0·05) associations were found between eye and airway symptoms elicited by fragrance products and perfume contact allergy (adjusted odds ratios 2·0–3·7) and hand eczema (adjusted odds ratios 1·6–2·6). In further analysis, similar and consistent results were found regarding severity of the symptoms. No associations were found between nickel contact allergy and the symptoms. Female sex and psychological vulnerability were independently associated with eye and airway symptoms elicited by fragrance products, but adjustment in multivariate analysis did not change the results regarding perfume contact allergy and hand eczema.Individuals with perfume contact allergy and/or hand eczema, as opposed to those without, have more frequent and more severe eye or airway symptoms after exposure to volatile fragrance products. Having hand eczema has the greatest impact on reporting eye and airway symptoms elicited by fragrance products. [ABSTRACT FROM AUTHOR]