How Syphilis Is Treated

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Syphilis is typically treated with penicillin, the same drug used to treat the infection since 1943. While the bacterial disease can be treated with other types of antibiotics, there are circumstances where penicillin is the only choice. The partner of an infected individual may also be presumptively treated to safeguard against infection. Other than antibiotics, no other form of treatment is effective in clearing a syphilis infection.

Medications

Syphilis treatment often requires a single injection. The course of therapy is largely directed by the stage of infection (primary, secondary, latent, tertiary) and other contributing factors.

Penicillin G is considered the drug of choice. For people allergic to penicillin, alternative drugs such as doxycycline, tetracycline, azithromycin, and ceftriaxone may be used. The only exceptions would be neurosyphilis (a late-stage complication affecting the brain and central nervous system) or congenital syphilis (where the infection is passed from mother to child during pregnancy) in which penicillin is the only option.

In most cases, the drug will be delivered with an intramuscular (IM) injection, usually in the gluteal muscle (buttocks). In severe cases, the drug may be given intravenously (via IV).

Unlike some bacterial infections in which people are presumed cured after completing therapy, people with syphilis need to undergo follow-up tests to confirm that the infection has cleared. While a person is generally not considered contagious 24 hours after completing treatment, some doctors will recommend abstinence until follow-up tests have been completed.

Treatment Recommendations

In 2015, the Centers for Disease Control and Prevention (CDC) issued updated recommendations on the treatment of syphilis that are still followed today:

  • Primary, secondary, or early latent syphilis: One intramuscular injection of Benzathine penicillin G 
  • Late latent syphilis, latent syphilis of unknown duration, or tertiary syphilis: Three intramuscular injections of Benzathine penicillin G delivered a week apart
  • Neurosyphilis or ocular syphilis: Aqueous crystalline penicillin G IV infusions delivered every four hours over 10 to 14 days, potentially followed by one intramuscular injection of the Benzathine penicillin G; alternative treatment with procaine penicillin G may be considered in some cases

While penicillin G is considered extremely effective in clearing a syphilis infection, some people may require additional treatments if follow-up tests do now show the anticipated drop in the volume (titer) of syphilis antibodies. Additionally, serious neurological and optical complications can occur and persist even after the infection has been treated.

The above recommendations for primary, secondary, early latent, and late latent syphilis apply for infants and children, as well as adults. Because the time between a primary infection and tertiary syphilis is very long (often more than 10 to 20 years), advanced syphilis is exceedingly rare in children.

Pregnant Women

Treatment for syphilis diagnosed during pregnancy follows the same recommendations for adults listed above. However, only penicillin G is known to be effective in preventing transmission to the unborn baby.

If a mother is allergic to penicillin, her doctor will need to desensitize her with a series of allergy shots. This would involve exposing the mother to smaller amounts of penicillin and increasing the dosage gradually to build tolerance so that she can eventually be treated with the antibiotic.

Concerns

In recent years, there have been growing concerns about the threat of antibiotic drug resistance in treating sexually transmitted diseases.

Many of the concerns stemmed from the use of oral antibiotics in treating gonorrhea, the practice of which led to widespread resistance and the abandonment of the single-pill approach. As a result, gonorrhea is today treated with a combination of the injectable and oral antibiotics.

Thus far, there have been no indications of this happening with syphilis and penicillin. There have, however, been signs of a developing resistance to azithromycin, mostly related to resistant strains of syphilis that first emerged in the 1950s with the introduction of antibiotics.

So, while epidemiologists continue to monitor for signs of antibiotic resistance, penicillin should be considered the safest and most reliable means of treating syphilis.

Sexual Partners

      • With primary syphilis, notification should be sent to anyone you've had sex with up to 90 days before the appearance of symptoms.
    • With secondary syphilis, notification should be sent to anyone you've had sex with up to six months before the appearance of symptoms.
    • With early latent syphilis, notification should be sent anyone you've had sex with up to a year before the appearance of symptoms.
  • If you have been diagnosed with syphilis, your sexual partners need to be notified and treated based, once again, on your stage of infection:In terms of treatment, most doctors treat any sexual partner as a confirmed infection, since it can take up to 90 days to get an accurate test result. However, if the exposure occurred more than 90 days after the appearance of symptoms, the doctor may choose to test the partner first.
    • Because the risk of infection decreases rapidly after the first year, partner notification may or may not be pursued. As a notifiable disease, your doctor is required by law to provide information about the infection to the public health authority; however, your name is not included in this report.
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