Syphilis is a chronic, systemic sexually transmitted disease caused by the pale (syphilis) spirochete. It is mainly transmitted through the sexual route and can be clinically manifested as stage I syphilis, stage II syphilis, stage III syphilis, latent syphilis and congenital syphilis (fetal syphilis). It is a disease listed as category B in the Prevention and Control of Infectious Diseases Law of the People’s Republic of China. What are the principles of medication for syphilis? 1, early syphilis medication principles: procaine penicillin G 800,000 units, once a day, intramuscular injection, for 15 days, the total dose of 12 million units. The skin test and injection of penicillin should be done in hospital. If there is a history of penicillin allergy, it can be changed to tetracycline, 500 mg each time, 4 times a day, orally, for 15 days, or doxycycline, 100 mg each time, twice a day, orally, for 15 days. 2, late syphilis medication principles: procaine penicillin G 800,000 units, once a day, intramuscular injection, for 20 days; can also use benzathine penicillin G 2.4 million units, once a week, intramuscular injection, a total of 3 times. Penicillin skin test and injection should be done in hospital, if there is a history of penicillin allergy, it should be changed to tetracycline, 500 mg each time, 4 times a day, orally, for 30 days; or doxycycline, 100 mg each time, 2 times a day, for 30 days. 3, cardiovascular syphilis medication principles: all patients with cardiovascular syphilis, should be hospitalized. If there is heart failure, wait for the heart function to return to normal, start injecting penicillin from small dose, such as aqueous penicillin G, day 1, 100,000 units, once a day, intramuscular injection; day 2, 100,000 units, twice a day, intramuscular injection; day 3, 200,000 units, twice a day, intramuscular injection, from day 4 onwards, daily intramuscular injection of procaine penicillin G 800,000 units, for 15 consecutive days as a course of treatment, a total of 2 courses of treatment. The interval between courses is 2 weeks. 1 day before receiving penicillin, prednisone can be given orally, 10 mg each time, twice a day for 3 days. 4, neurosyphilis medication principles: all suffer from neurosyphilis, should also be hospitalized. The main use of penicillin treatment, procaine penicillin G 1.2 million units, intramuscular injection, once a day, while oral propofol, 0.5 grams each time, 4 times a day, for 14 days; if necessary, combined with knotted star penicillin G 2.4 million units, once a week, intramuscular injection, for 3 weeks, before the injection of penicillin, need to oral prednisone, 10 mg each time, twice a day, for 3 days. 5, congenital syphilis medication principles: early congenital syphilis: procaine penicillin G, 50,000 units per kg of body weight per day, intramuscular injection, for 14 days. Late congenital syphilis (over 2 years old): procaine penicillin G, 50,000 units per kg of body weight per day, intramuscular injection, for 10 consecutive days as a course of treatment, stop 1 week, can be injected again for 1 course of treatment. Injectable medication for children with congenital syphilis must be administered in a hospital. For those who are allergic to penicillin, treatment can be changed to erythromycin, 7.5-12.5 mg per kg body weight per day, divided into 4 doses, for 30 days.