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Syphilis: Diagnosis and treatment

With the right antibiotic, syphilis can be cured.

The antibiotic works by killing the corkscrew-shaped bacteria in your body that cause syphilis.

Corkscrew-shaped bacteria

How is syphilis diagnosed and treated?

Patient having blood drawn
If your doctor recommends that you get tested for syphilis, knowing what to expect can help put your mind at ease. Here’s what happens from getting tested to treated.

Step 1: Take a blood test

If you might have syphilis, your doctor will order a blood test. If this blood test is positive, the lab typically performs a second test on your blood to confirm that you have syphilis. If you have syphilis, you need treatment.

Step 2: Determine stage

Doctor with patient
Your doctor will determine the stage of infection by reviewing information from your exam and asking you questions.

Step 3: Treat and cure

To cure syphilis, you need to receive the right antibiotic. Here’s how you may get the antibiotic:

  • Early stage: One shot of penicillin

  • Late stage: Three shots of penicillin, with one shot given each week for three weeks

  • Syphilis affects your nervous system: Penicillin given through an IV (intravenous) infusion, with treatment given once a week for two weeks.

To treat syphilis with penicillin, you need a shot or IV infusion. Taking penicillin pills cannot cure you.

You should not have sex for at least 1 week after treatment and until all symptoms have gone away.

Smiling doctor with patient

Step 4: Follow-up with your doctor

While treatment can cure you, follow-up appointments are necessary. Some people need more than one shot of penicillin. Others get re-infected. During your follow-up appointments, you’ll have:

  • A blood test to make sure you no longer have syphilis

  • Other medical tests if the disease was caught late

Step 5: Partner notification

Doctor with patient
You should tell your partner(s) that you were diagnosed with syphilis. This is important so that they can be tested and, if necessary, treated. It will also prevent them from giving the infection back to you or to other people.

Your doctor is required by law to report all syphilis infections to the local health department. If you prefer, the health department can help notify your partner(s) that they need to be tested.

Step 6: Prevent repeat infections

When you start having sex again, use latex condoms and/or dental dams to prevent getting syphilis again or other sexually transmitted diseases.

Condom inside a wallet
While the right antibiotic can cure syphilis, it cannot undo damage already done. If syphilis caused hearing loss, you’ll continue to have hearing loss after being treated. If the syphilis has damaged your heart, you may need surgery to repair the damage.

How is syphilis treated if you are allergic to penicillin?

If you are allergic to penicillin, tell your doctor before you get your first shot or IV of penicillin.

Some people can be treated with another antibiotic, such as doxycycline or tetracycline. If your doctor decides to treat you with one of these antibiotics, you will need several follow-up appointments. These antibiotics can be less effective at treating syphilis.

If you are pregnant and allergic to penicillin, you must treat with penicillin. It’s the only antibiotic that can treat both mother and baby. A method called “desensitization” is used so that you can be safely treated with penicillin.

Treatment for syphilis is essential if you are pregnant. Treatment could save your baby’s life and prevent birth defects.

Some people feel sick within hours of syphilis treatment

About 10% of people treated for syphilis feel sick within a few hours. They may develop one or more of the following:

  • Fever

  • Chills

  • Flushing

  • Achy muscles

  • Racing heart

  • Headache

  • Rash

Many people fear these signs and symptoms signal a serious allergic reaction to the penicillin. Research shows this isn’t an allergic reaction. However, it’s unclear why some people develop this reaction. It’s possible that the person’s immune system is reacting to the dying bacteria.

The reaction clears quickly on its own, usually disappearing completely within 24 hours.

While you feel sick, it can help to drink lots of water and take medicine to reduce the fever.

Keep all follow-up appointments with your doctor

By keeping all of your follow-up appointments, you will get the care you need. That care may include an HIV test. People who have had syphilis have a higher risk of developing an HIV infection.

If the syphilis was caught in a late stage, it may have affected your body in other ways. You may need other medical tests. People also need follow-up syphilis blood tests to make sure the syphilis treatment worked.

Taking good care of yourself also plays an important role in your treatment. You’ll see what dermatologists recommend at:

Syphilis: Self-care

Getty Images

Evans A. “No longer on display.” Dermatol World. 2019:29(9):42-7.

Forrestel AK, Kovarik CL, et al. “Sexually acquired syphilis Historical aspects, microbiology, epidemiology, and clinical manifestations.” J Am Acad Dermatol 2020;82:1-14.

Giesey RL, Delost GR, et al. “Acute pustular eruption following a Jarisch-Herxheimer reaction in the treatment of syphilis.” JAAD Case Rep. 2018;4(3):259-61.

Haran Chandrasekar PH. “Syphilis treatment and management.” Medscape. Updated Jul 18, 2017. Last accessed Apr 3, 2020.

Stary G, Stary A. “Sexually transmitted infections.” In: Bolognia JL, et al. Dermatology. (fourth edition). Mosby Elsevier, China, 2018: 1447-59.

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention. “Syphilis: Pocket guide for providers.” Last accessed Apr 3, 2020.