How Is Syphilis Treated?

If you have been told you have syphilis, or you think you might, the most important thing to know is that it can be cured. Treatment is prescribed by a clinician, so this page explains what to expect rather than how to dose anything.

How is syphilis treated?

The CDC says penicillin G, given parenterally (that is, by injection rather than by mouth), is the preferred drug for treating syphilis at all stages. The NHS says syphilis is treated with antibiotics, which can be injections, tablets or capsules.

Which form of penicillin is used, and how long treatment lasts, depends on the stage and on what symptoms are present. Later stages need longer treatment. This is a decision for a clinician, and the schedule isn’t something to work out yourself.

Can I take other antibiotics instead of penicillin?

Questions about alternatives, such as a short course of tablets, come up often. The CDC calls penicillin G the preferred drug, and says combinations that include oral penicillin are not considered appropriate for syphilis. Which antibiotic is right for you depends on your stage, so it has to be decided by a clinician.

If you are allergic to penicillin, tell your clinician. For pregnancy, the CDC says there are no proven alternatives to penicillin, so people who report a penicillin allergy are desensitized and then treated with penicillin.

What happens after treatment?

Treatment is not the end of the process. The CDC says follow-up testing is necessary to make sure treatment was successful. The NHS says you will need to be retested several times in the first 12 months, and you can order the follow-up blood tests online.

Blood tests that measure antibody levels usually fall after treatment, and may eventually become negative. The other type of syphilis blood test usually stays positive for life even after a cure, so a positive result later does not always mean a new infection.

Some people get a fever, headache and muscle aches within the first 24 hours of treatment. The CDC calls this the Jarisch-Herxheimer reaction. It is a reaction to treatment, not an allergy.

Do my sexual partners need treatment?

Yes. The NHS says current and recent sexual partners need testing and treatment, so tell them so they can order a test and see a clinician for treatment.

The CDC advises that people who had sexual contact with someone diagnosed with early syphilis in the previous 90 days should be treated presumptively, even if their blood tests are negative. Partners are generally advised to be notified if contact was within 3 months (plus the length of symptoms) for primary syphilis, 6 months (plus symptoms) for secondary syphilis, and 1 year for early latent syphilis.

The NHS also advises no sex, whether vaginal, anal or oral, until 2 weeks after you and your partner have both finished treatment.

What if I am pregnant?

Syphilis in pregnancy can pass to the baby, and this is called congenital syphilis. The CDC says it can lead to a low-birth-weight baby, early delivery or stillbirth. A baby may have no signs at birth but can develop serious problems within weeks if not treated, including cataracts, deafness or seizures.

That is why the CDC says all pregnant people should have a syphilis blood test at their first prenatal visit, and some again at 28 weeks and at delivery. Penicillin G is the only known effective treatment for fetal infection and for preventing congenital syphilis.

After treatment in the second half of pregnancy, the CDC advises seeking obstetric care for any fever, contractions or reduced movement from the baby.

What happens if syphilis isn’t treated?

Early signs, like the first sore, go away without treatment, but the infection doesn’t. The CDC says untreated syphilis can later affect the heart, blood vessels, brain and nervous system, and can reach the eyes and ears at any stage. That is why a sore or rash that “went away” still needs a test.

Should I be tested for other infections too?

It is worth doing. The NHS says you may have tests for other sexually transmitted infections at the same time as a syphilis test. The CDC also notes that having a sore or break in the skin from an STI such as syphilis may allow HIV to enter the body more easily, so an HIV test is worth ordering online too. Making sure sex partners are tested (they can order a test online) and treated, and using condoms the right way every time you have sex, lowers the chance of getting syphilis again.