Background/aim The Jarisch-Herxheimer reaction (JHR) is an acute systemic event that can occur during the treatment of spirochetal infections, especially Treponema pallidum in patients with syphilis. JHR has clinical characteristics of an inflammatory reaction to antibiotic treatment and can occur with many medications as long as the antitreponemal concentrations are sufficiently high.
Methods The incidence of and risk factors for JHR were investigated retrospectively among 1125 patients with syphilis. A total of 357 patients (32%) had secondary syphilis, 129 (12%) primary, 178 (16%) early latent, 174 (15%) late latent and 285 (25%) latent unknown duration; two patients had tertiary syphilis.
Results Sixteen patients (1.4%) developed JHR. All JHRs occurred in patients with secondary and latent syphilis treated with penicillin.
Conclusions JHR occurred much less frequently than in previously reported studies. It is important that dermatologists recognize the clinical characteristics of JHR so that it is not misinterpreted as an allergic reaction to treatment.