Objectives The objective of this retrospective study was to summarise the clinical manifestations of, and to analyse the incidence and risk factors of, Jarisch–Herxheimer reaction (JHR) during the treatment of children with symptomatic congenital syphilis.

Methods Clinical data of 60 children with clinically and laboratory diagnosed congenital syphilis, hospitalised in Beijing Ditan Hospital between January 2010 and November 2015, were collected and analysed.

Results A total of 11 patients with congenital syphilis (11/60, 18.3%) developed JHR. JHR occurred in 1–6 hour after the first dose of penicillin. Common clinical manifestations included fever (11/11, 100%), irritability (11/11, 100%), rapid pulse and breathing (11/11, 100%), exacerbation of existing rash (5/11, 45.6%) and chills (3/11, 27.3%). Of the 11 patients who developed JHR, 9 patients (9/11, 81.8%) had bone syphilis, 10 (10/11, 90.9%) had more than three organs affected by syphilis and 10 (10/11, 90.9%) had a high plasma concentration of rapid plasma reagin (RPR) (≥1:256); these percentages were significantly higher than in patients who had not developed JHR (p<0.05), suggesting that the occurrence of JHR was related to bone syphilis, having more than three organs affected by syphilis and a high plasma concentration of RPR.

Conclusions Clinicians should be familiar with the risk factors for this reaction and its common clinical manifestations.