Syphilis Treatment

Syphilis is a treatable infection – especially in its primary and secondary stages. It is more difficult to treat in its tertiary stage.

Primary and secondary syphilis can be successfully treated with a single dose of penicillin. Penicillin is given as an injection in one of the large muscles like over the arm or on the buttocks.


Penicillin is the drug of choice in primary and secondary syphilis. Those who are allergic to penicillin are prescribed other drugs as pills or injections. Later stages of the disease need to be treated with three penicillin injections, which are given at weekly intervals.

A small number of people experience a reaction to the antibiotics known as the Jarisch-Herxheimer reaction. It is thought that the reaction is triggered by the toxins released when a large number of bacteria are killed after antibiotic treatment. The Jarisch-Herxheimer reaction causes flu-like symptoms such as fever, headaches and muscle and joint pain. These symptoms normally only last 24 hours and are not serious. The symptoms can be treated with paracetamol.

For Primary, Secondary, or Early Latent syphilis less than 1 year 2.4 million units IM (intramuscular) of Benzathine Penicillin G in a single dose is given. For latent infection over 1 year and latent infection of unknown duration 2.4 million units IM of Benzathine Penicillin G in 3 doses each at 1 week intervals (7.2 million units total) is given.

Treatment during pregnancy, childhood and congenital syphilis

Treatment during pregnancy should be the penicillin regimen appropriate for the stage of syphilis. In first and second trimesters single dose benzathine penicillin is given.

In the third trimester two doses of benzathine penicillin one week apart is chosen.

For late syphilis, treatment should be like nonpregnant (avoiding tetracyclines). Alternatives include ceftriaxone 500 mg IM for 10 days.

For congenital syphilis 100,000-150,000 units/kg/day (50,000 units/kg/dose IV every 12 hours) of Aqueous Crystalline Penicillin G during the first 7 days of life and every 8 hours thereafter for a total of 10 days is given. An alternative regimen is – 50,000 units/kg/dose IM of Procaine Penicillin G in a single dose for 10 days.

Among children with primary, secondary or early latent phase (less than 1 year), 50,000 units/kg IM of Benzathine Penicillin G in a single dose (maximum 2.4 million units) is given. For children with latent period more than a year or of unknown duration 50,000 units/kg IM of Benzathine Penicillin G for 3 doses at 1 week intervals (maximum total 7.2 million units) is given.

Follow up after antibiotics course

Once the course of antibiotics is finished the patient needs to visit the clinic again for a follow up blood test. This checks if the infection is gone.

Detection and treatment of the sexual partner(s)

All sexual partners of an infected person over the last 90 days are considered infected. They need to be identified, tested and treated if needed. Some people can feel angry, upset or embarrassed about discussing syphilis with their current partner or former partner.

GPs and physicians help in disclosing the exposure to risk to these sexual partners using a ‘contact slip’. This slip explains to that person that they may have been exposed to syphilis and that they should go for a check-up. The slip does not have the name of the infected person on it.

Treating tertiary syphilis

Treatment of tertiary syphilis requires longer courses of antibiotics and may need intravenous treatment. Treatment can only stop the infection. It fails to repair the damage that is caused to the brain, eyes or other organs by syphilis.

For neurosyphilis or affliction of the nerves and brain 3 to 4 million units IV of Aqueous Crystalline Penicillin G every 4 hours for 10-14 days (18-24 million units/day) is given.


Patients who acquire syphilis are at significant risk of reinfection, and should therefore be regularly screened for syphilis. All patients should be offered screening for other sexually transmitted infections, including HIV.



Further Reading

  • All Syphilis Content
  • What is Syphilis?
  • Syphilis Diagnosis
  • Syphilis Prevention
  • Syphilis History

Last Updated: Jun 5, 2019

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

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