Background: It is not known whether alopecia areata (AA) is associated with a greater or reduced risk for infection., Aim: We undertook a population-based study exploring associations between AA and common infections., Methods: We extracted primary care records from the UK Oxford-Royal College of General Practitioners Research and Surveillance Centre database (trial registration: NCT04239521). The incidence of common and viral infection composite outcomes, and individual respiratory, gastrointestinal (GI), skin, urinary tract, genital and herpes infections, were compared in people with AA (AA group, n = 10 391) and a propensity-matched control group (n = 41 564). Adjusted hazard ratios (aHRs), controlling for sociodemographic and clinical covariates, and comorbidities were used to estimate the association between AA and each infection over 5 years., Results: The incidence (per 100 person-years) of common infections was slightly higher in the AA group [14.2, 95% confidence interval (CI) 13.8-14.6] than the control group (11.7, 95% CI 11.5-11.9). In adjusted analysis, positive associations were observed for composite outcomes (common infections aHR 1.13, 95% CI 1.09-1.17; viral infections aHR 1.11, 95% CI 1.07-1.16) and with respiratory tract, GI, skin and herpes simplex infections (aHR range 1.09-1.32). Excluding people in the control group without a recent consultation with their general practitioner showed no association between AA and infection (common infections aHR 1.01, 95% CI 0.98-1.05, viral infections aHR 0.99, 95% CI 0.95-1.03)., Conclusions: The association between AA and common infection may represent a higher propensity of people with AA to engage with healthcare services (and thereby to have infections recorded), rather than a true association between AA and infection. Overall our findings suggest that AA is not associated with a clinically significantly increased or decreased incidence of common infections., Competing Interests: Conflict of interest S.deL. is Director of RCGP RSC, he has received funding for projects from Astra Zeneca, Daiichi Sankyo, Eli Lilly, GSK, MSD, Nova Nordisk, Seqirus and Takeda – all through his universities and none related to this study. W.S.C. is an employee of Pfizer Ltd. S.H. and A.G.M. have undertaken paid consultancy for Pfizer. S.H. and C.T. are investigators on the Pfizer-funded ALLEGRO clinical trial. A.G.M., M.H., A.E.M. and S.H. are members of the British Association of Dermatologists guidelines group for alopecia areata., (© The Author(s) 2022. Published by Oxford University Press on behalf of British Association of Dermatologists.)