Answer
It is a temporary inflammatory reaction after syphilis treatment that can cause fever, chills, headache, sweating and muscle or joint pain. Clinical assessment is needed if symptoms are severe or unexpected.
Sources for this answer
- Benzylpenicillin benzathine 2.4 Million I.U. powder for suspension for injection — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.