Antibiotics for syphilis

Examples

Penicillin is the antibiotic most commonly used to treat syphilis. Penicillin is usually given as a shot (injection).

If you are allergic to penicillin, your health professional may prescribe another antibiotic, such as doxycycline, tetracycline, ceftriaxone, or azithromycin, for the earlier stages of syphilis. Later stages of syphilis may require treatment with penicillin.

Penicillin is the only antibiotic that should be used during pregnancy. If you are pregnant and think you may be allergic to penicillin, discuss your allergy with your health professional.

How It Works

Antibiotics destroy the bacteria that cause syphilis.

Why It Is Used

Antibiotics are indicated if you have a positive blood test for syphilis during routine screening or have symptoms suggestive of syphilis. Exposed sex partners of a person with syphilis and babies born to women who have syphilis also require treatment.

The amount of antibiotics used and how often the medication is taken are based on the stage of the illness. For example, if neurosyphilis is present, you will need to receive antibiotics for 10 days to 2 weeks.

How Well It Works

Treatment with penicillin cures most cases of syphilis in any stage.¹ Antibiotics prevent further complications of syphilis but may not reverse damage that has already occurred.

Follow-up examination and blood testing for cure should be done at 6 and 12 months after the antibiotics are given (and may be done at 24 months in latent syphilis) to be sure the infection is cured. Follow-up examination and testing may be done at 3, 6, 9, 12, and 24 months if human immunodeficiency virus (HIV) infection was also present at the time of treatment.²

Syphilis passed to a baby from the mother (congenital syphilis) may be prevented if pregnant women are treated before the 16th to 18th weeks of pregnancy. Treatment after 16 to 18 weeks will cure the infection and stop the damage to the baby, but it may not reverse damage already caused by the infection.

Side Effects

A Jarisch-Herxheimer reaction is a reaction to antibiotic treatment of syphilis that involves fever and headache. It may occur up to 8 hours after the initial treatment of early syphilis. Oral steroids, such as prednisone, or nonsteroidal anti-inflammatory drugs (NSAIDs) taken before the antibiotic is given may prevent the Jarisch-Herxheimer reaction.³ However, most experts do not recommend routine use of this approach, because the reaction is usually mild and of limited duration.

The Jarisch-Herxheimer reaction occurs in 50% to 75% of people with early syphilis who receive treatment with antibiotics.³ The reason this reaction occurs is unclear, but it may be caused by the toxins released from the syphilis bacteria as they are destroyed by antibiotics. A Jarisch-Herxheimer reaction is not the same as an allergic reaction to penicillin.

Pregnant women in the second half of pregnancy have an increased risk for premature labor and fetal distress if they have a Jarisch-Herxheimer reaction. However, pregnant women who have syphilis should still be treated because congenital syphilis is more likely to cause fetal death. Pregnant women who develop symptoms of this reaction need to notify their health professional.

See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)

What To Think About

Guidelines for the treatment of syphilis and other sexually transmitted diseases are updated by the U.S. Centers for Disease Control and Prevention (CDC) on an ongoing basis.

Antibiotic treatment can cure syphilis and prevent complications. The complications of tertiary-stage or congenital syphilis may not be reversed with treatment; but, the progression of the disease will be stopped.

Penicillin is the preferred drug for treating syphilis.¹ Although penicillin is the standard therapy for the treatment of neurosyphilis, congenital syphilis, or syphilis acquired or detected during pregnancy, other antibiotics (such as ceftriaxone) may also be considered.

Penicillin is the only proven therapy that has been widely used for neurosyphilis, congenital syphilis, or syphilis during pregnancy. When syphilis is treated with a drug other than penicillin, closer follow-up is needed to monitor for cure or relapse.

Penicillin passes into breast milk in small amounts, but it is not usually harmful to a nursing baby. Doxycycline and tetracycline all pass into breast milk and may affect the bone and tooth development of a nursing baby. If you are breast-feeding a baby, do not take any of these medications without first talking to your health professional.

The CDC recommends that a follow-up examination and testing for cure be done at 6 and 12 months after antibiotics are given (testing may also be done at 24 months in latent syphilis) to be sure the infection has been cured. Follow-up examination and testing may be recommended at 3, 6, 9, 12, and 24 months if HIV infection was also present at the time of treatment.²

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Author:	Colleen Cronin	Last Updated October 26, 2005
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine Jeanne Marrazzo, MD, MPH - Infectious Disease
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