Tongue kissing is generally not contagious syphilis, only extreme conditions may spread. 1. Syphilis is a sexually transmitted disease caused by syphilis spirochete infection, through sexual transmission, blood transmission, mother-to-child vertical transmission, tongue kissing does not belong to the sexual act, and will not cause the spread of syphilis disease, there is no syphilis virus in the saliva, the disease spread through the saliva belongs to the respiratory tract diseases, such as: influenza, pneumonia, rubella, meningitis and so on. 2. Tongue kissing process, if both sides have oral breakage, bleeding gums, oral ulcers, etc., the other oral blood can be spread through the broken skin caused by the transmission, but the general oral bleeding is small, containing the amount of virus is relatively low, and the transmission of harsh conditions, so there are generally few of such cases. Suspected syphilis infection, you need to go to a professional hospital for standardized diagnosis and timely treatment.