Doctor speaking to patient about using penicillin to treat an STD

Can Penicillin Treat STDs?

Written on September 22, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

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Many people wonder, can penicillin treat STDs? The short answer is yes, penicillin can treat sexually transmitted diseases. Although penicillin is no longer used to treat gonorrhea, it is effective for treating syphilis. Let’s take a closer look.

Penicillin to Treat Syphilis

Syphilis is spread by contact with a sore on the genitals, anus, rectum, lips, or mouth, or from mother to child during pregnancy. If a pregnant person has untreated syphilis and the infection is transmitted to the fetus, it can cause death. In 2012, mother-to-child transmission of syphilis resulted in an estimated 143,000 early fetal deaths/stillbirths, 62,000 neonatal deaths, and 44,000 babies being born preterm/low-birth-weight. [1]

To cure syphilis, the new World Health Organization (WHO) guideline strongly recommends a single dose of benzathine penicillin—a form of the antibiotic that is injected by a doctor or nurse into the infected patient's buttock or thigh muscle. This is the most effective treatment for syphilis; more effective and cheaper than oral antibiotics.

Benzathine penicillin was recognized by the 69th World Health Assembly in May 2016 as an essential medicine that has been in short supply for several years. Reports of shortages have been received by WHO from antenatal care representatives and providers in countries with high burdens of syphilis. The WHO is working with partners to identify countries with shortages and help monitor global availability of benzathine penicillin to close the gap between national needs and supply of the antibiotic.[1]

According to the Centers for Disease Control and Prevention (CDC), a single injection of long-acting benzathine penicillin G can cure the early stages of syphilis. This includes primary, secondary, or early latent syphilis. The CDC recommends three doses of long-acting Benzathine penicillin G at weekly intervals for late latent syphilis or latent syphilis of unknown duration. Treatment will cure the infection and prevent further damage, but it will not repair damage already done. Selecting the right penicillin preparation is important to properly treat and cure syphilis.[2]

According to Mayo Clinic, penicillin is the only recommended treatment for pregnant people with syphilis. People who are allergic to penicillin can undergo a desensitization process that may allow them to take penicillin.

Even if you're treated for syphilis during your pregnancy, your newborn child should be tested for congenital syphilis and if infected, receive antibiotic treatment.

The first day you receive treatment, you may experience what's known as the Jarisch-Herxheimer reaction. Signs and symptoms include fever, chills, nausea, achy pain, and headache. This reaction usually doesn't last more than one day.

After you're treated for syphilis, your doctor will ask you to [3]:

  • Have periodic blood tests and exams to make sure you're responding to the usual dosage of penicillin. Your specific follow-up will depend on the stage of syphilis you're diagnosed with.
  • Avoid sexual contact with new partners until the treatment is completed and blood tests indicate the infection has been cured.
  • Notify your sex partners so that they can be tested and get treatment if necessary.
  • Get tested for HIV infection.

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History of Penicillin to Treat Gonorrhea

In the 1940s, gonorrhea was of sufficient import to have been one of the first infections treated with penicillin as investigators explored the potential uses of the “wonder drug.” Since then, gonorrhea therapy recommendations have evolved continuously, both through dose modification of existing drugs and the introduction of new drugs.

Soon after its introduction, penicillin became the preferred treatment for gonorrhea, in part because of its activity against Treponema pallidum, the causative agent of syphilis and a somewhat greater public health priority at the time.

By the late 1950s and early 1960s, much gonorrhea therapy utilized penicillin: a version combined with aluminum monostearate, benzathine- or procaine-penicillin which—possibly reflecting a lack of an authoritative recommendation—were used in varying doses. Soon after it became widely used for gonorrhea, numerous investigators also documented progressive increases in penicillin minimal inhibitory concentration (MIC), the amount of medicine required to reliably inhibit the growth of N. gonorrhea in laboratory experiments.

Increased penicillin MICs predicted the likelihood of treatment failure in patients. Subsequently, despite continuing increases in penicillin MICs, periodic escalation of recommended penicillin doses took advantage of the drug’s low toxic/therapeutic ratio and allowed penicillin to remain a preferred drug for gonorrhea for over 40 years.

Over that period, the amount of drug recommended for gonorrhea treatment increased over 100-fold to an ultimate recommendation of 4.8 Mu of aqueous procaine penicillin G.

In the early 1970s, penicillin efficacy was further enhanced following demonstration that co-administration of probenecid increased penicillin serum levels and delayed excretion of the drug, increasing gonorrhea cure rates to close to 100%.

In the mid-1970s, however, the era of penicillins as preferred gonorrhea therapy ended. Higher doses of procaine penicillin were problematic due to the increased risk of patients reacting badly to the procaine, and injection discomfort associated with medication volume. Additionally, gonococci emerged with genetic mutations conveying antimicrobial resistance, including the well-known beta-lactamase plasmid [penicillinase-producing N. gonorrhoeae (PPNG)], which allows penicillin inactivation in a single step. This resistance to penicillin created a pressing need for alternative gonorrhea therapy.[4]

Everlywell Offers Syphilis Tests and STD Consults

Everlywell’s at-home lab test will check for antibodies to Treponema pallidum, the bacteria responsible for causing the sexually transmitted infection syphilis. In the event that your test results are positive for syphilis, you’ll have the opportunity to connect with our independent physician network at no additional cost to discuss your particular case.

Everlywell also offers online STD consults in 2 hours or less via video call. You can speak with a healthcare provider, get treatment, and have a prescription sent directly to your pharmacy (if applicable).

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  1. New guidelines for chlamydia, gonorrhea and syphilis. Pan American Health Organization. 8/30/2016. Accessed on 9/8/2023.
  2. What is the treatment for syphilis? Centers for Disease Control and Prevention. Last reviewed 8/11/2023. Accessed on 9/8/2023.
  3. Syphilis. Mayo Clinic. Accessed on 9/8/2023.
  4. Hook EW, Kirkcaldy RD. A brief history of evolving diagnostics and therapy for gonorrhea: Lessons learned. Clinical Infectious Diseases, Volume 67, Issue 8, 15 October 2018, Pages 1294–1299,
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