Hard chancre is a symptom of stage 1 syphilis, and having a hard chancre does not necessarily mean that syphilis will be detected immediately. Syphilis has a window period, which refers to an infection with the syphilis spirochete that does not reflect antibodies in itself, in about 15-30 days. If you have a chancre-like lesion on your external genitalia and are negative for syphilis, do not completely rule out syphilis, and you may choose to get tested again for the spirochetes 15-20 days later. The hard chancre is easy to misdiagnose and is itself self-healing, subsiding spontaneously 15-20 days after infection and treated with regular long-acting penicillin. In case of penicillin allergy, alternative treatment with cephalosporins or doxycycline is an option.