Syphilis can usually be cured with doxycycline. Alternative treatments such as doxycycline are usually considered in cases where the patient is allergic to penicillin. Syphilis is a sexually transmitted disease caused by the infection of syphilis spirochetes and can be categorized into early syphilis and late syphilis according to the course of the disease. Once the diagnosis of syphilis is confirmed, it is recommended that the patient undergoes deworming treatment as early as possible and follows the principles of standardized medication, adequate dosage, and regular course of treatment, which can usually lead to clinical cure. At present, penicillin is the drug of choice for the treatment of syphilis, but for those who are allergic to penicillin or unable to use penicillin, doxycycline and other antiplatelet therapy are usually used, and the use of doxycycline in full dosage and full course of treatment in accordance with the doctor’s instructions is usually also a cure for syphilis. Doxycycline may cause some adverse reactions, such as abdominal pain, diarrhea, nausea, vomiting and other gastrointestinal reactions, erythema, maculopapular rash and other allergic reactions. Doxycycline is contraindicated in people with a history of allergy to tetracyclines. When using doxycycline, it should be noted that the drug may cause overgrowth of drug-resistant bacteria, so in the event of a secondary infection you need to stop using the drug immediately and seek medical attention. Doxycycline can be taken with milk and food. Syphilis patients, whether using doxycycline or other drugs, should be standardized treatment under the guidance of the doctor, to adhere to the regular medication, and can never stop taking the drug on their own.