Third-stage syphilis is contagious. Although the titers in third-stage syphilis might be lower than those in the first and second stages, it still has the ability to infect others. Moreover, third-stage syphilis can easily lead to many complications, affecting other tissues and organs of the body. Therefore, third-stage syphilis is very serious. Once third-stage syphilis occurs, one must be particularly vigilant, seek timely treatment in a reputable hospital early, enhance their immunity, and avoid having a history of unprotected sexual activity.