Background: Eosinophilic granulomatosis with polyangiitis (EGPA), is a rare ANCA-associated systemic vasculitis. Its overlapping features with other vasculitic or eosinophilic diseases, and the wide and heterogeneous range of clinical manifestations, often result in a delay to diagnosis., Objective: To identify red flags that raise a suspicion of EGPA to prompt diagnostic testing and to present an evidence-based clinical checklist tool for use in routine clinical practice., Methods: Systematic literature review and expert consensus to identify a list of red flags based on clinical judgement. GRADE applied to generate a strength of recommendation for each red flag and to develop a checklist tool., Results: 86 studies were included. 40 red flags were identified as relevant to raise a suspicion of EGPA and assessed by the experts as being clinically significant. Experts agreed that a diagnosis of EGPA should be considered in a patient aged ≥6 years with a blood eosinophil level >1000 cells/µL if untreated and >500 cells/µL if previously treated with any medication likely to have altered the blood eosinophil count. The presence of asthma and/or nasal polyposis should reinforce a suspicion of EGPA. Red flags of asthma, lung infiltrates, pericarditis, cardiomyopathy, polyneuropathy, biopsy with inflammatory eosinophilic infiltrates, palpable purpura, digital ischaemia and ANCA positivity, usually anti-myeloperoxidase, among others, were identified., Conclusion: The identification of a comprehensive set of red flags could be used to raise a suspicion of EGPA in patients with eosinophilia, providing clinicians with an evidence-based checklist tool that can be integrated into their practice., Competing Interests: Declaration of competing interest Iñigo Rúa-Figueroa: Lectures and advisors boards for GSK. No other conflicts of interest. Roser Solans Laqué: Honoraria for consultancy and conferences from GSK, and conferences from CSL- Vifor. Marina Blanco Aparicio declares to have received payment or honoraria for lectures, presentations, speakers’ bureaus, or educational events and support for attending meetings and/or travel for AstraZeneca, GSK, Sanofi, Chiesi, TEVA and Faes. Ismael García Moguel: Consultant and speaker: Novartis, AstraZeneca, Teva, Novartis, GSK, Sanofi Genzyme, Chiesi, Allergy therapeutics, Leti, Stallergenes, ALK-Abelló, Mundipharma, Pfizer, and Orion Pharma. PI clinical trials: Novartis, GSK, AstraZeneca, Sanofi Genzyme. Ricardo Blanco: Grants/research support from AbbVie, MSD, and Roche, and had consultation fees/participation in a company-sponsored speaker's bureau from AbbVie, Pfizer, Roche, Lilly, UCB, Bristol-Myers, GSK, Janssen, Novartis and MSD. Francisco Pérez Grimaldi: Honoraria for conferences from AstraZeneca, GSK, Sanofi, Novartis, Chiesi, Teva, Esteve, Menarini y Boehringer-Ingelheim. Ana Noblejas Mozo: Colaboration with CSL Vifor, Gebro Pharma, Astra Zeneca. Colaboration in a vasculitis meeting with patients: CSL Vifor. Honoraria for consultancy from GSK. Moises Labrador Horrillo: Payment for lectures including service on speakers’ bureaus from: AstraZeneca, GSK, Novartis and Sanofi. Consultancy from: AstraZeneca, Novartis and GSK. J.M. Álvaro-Gracia: Honoraria for lecturing, advisories and Congress attendance from AbbVie, AstraZeneca, Galapagos, Gilead, Pfizer, Novartis, GSK, Lilly, MSD y UCB. Christian Domingo Ribas. CDR has acted as consultant for GSK, AstraZeneca and Sanofi and has received funding for travel or speaker fees from ALK, Almirall, AstraZeneca, Boehringer Ingelheim, Chiesi, GSK, Menarini, MSD, Novartis, Stallergenes and Pfizer. Georgina Espígol-Frigolé: Honoraria for consultancy from Janssen, GSK and CSL-Vifor. Congress attendance from Boehringer-Ingelheim. Fernando Sánchez Toril. I have received personal fees (payments for presentations, advisory boards, etc.) from: ALK, AstraZeneca, Bial, Boehringer Ingelheim, Chiesi, FAES, Gebro Pharma, GSK, Menarini, Novartis, Pfeizer, TEVA and Sanofi. I have participated in clinical trials and received research grants from: AstraZeneca, Chiesi, GSK, Novartis, TEVA, Sanofi. I am not employed (including part-time) in any pharmaceutical industry. I do not maintain any relationship with the tobacco industry. Francisco Ortiz Sanjuán: Advisor, Review Panel member or Consultant fee from GSK, Grünenthal and received financial aid for attendance at medical conferences from Lilly. Ebymar Arismendi: Honoraria for consultancy, advisory board and/or conferences from GSK, AstraZeneca, MSD, Novartis, Chiesi, Gebro Pharma and Sanofi-Genzyme. Maria C Cid: Consulting fees from GSK, AbbVie, CSL- Vifor and AstraZeneca; royalties from UpToDate, and a research grant from Kiniksa Pharmaceuticals Corp., (Copyright © 2024. Published by Elsevier B.V.)