Syphilis: causes, treatment, prevention, and more

Syphilis is a bacterial infection typically transmitted through close contact during sex.

You can contract syphilis during vaginal, anal, or oral sex. It can also be passed from mother to baby during pregnancy. The infection spreads from person-to-person through contact with a syphilis rash or sore.

Syphilis doesn’t go away on its own, but the good news is it’s easily treatable—usually with a shot of penicillin. Here’s more on syphilis treatment, symptoms, and prevention.

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Syphilis is on the rise in the United States (Ghanem, 2020). While the infection is easily treatable, the bad news is it can be sneaky to detect. 

Without treatment, syphilis progresses through three different stages. Some stages show obvious symptoms of syphilis, while other times, there are no symptoms at all—despite the infection being active and contagious.

The stages of syphilis follow a predictable pattern. Here’s a bit more about each (Tudor, 2021):

• Primary syphilis: The first stage starts when you get infected. You may notice a hard, painless sore (called a chancre) typically on mucous membranes like the genitals, mouth, or anus. Some people never develop a sore at all or don’t notice they have one. The sore will typically heal on its own even without treatment, but that doesn’t mean the infection is gone. 

• Secondary syphilis: Roughly one in four people with untreated primary syphilis develop secondary syphilis. This stage is characterized by a non-itchy rash on the palms of the hands, soles of the feet, chest, arms, or back. You may also get white or grey lesions on your genitals. Flu-like symptoms can appear, including fever, swollen lymph nodes, headaches, muscle pain, sore throat, and weight loss. Like primary syphilis, the symptoms of secondary syphilis can disappear on their own. But again, if left untreated, the infection remains and can become deadly.

• Tertiary syphilis: Without treatment, secondary syphilis progresses to tertiary syphilis. This advanced stage affects organs in the body, causing irreversible heart issues, neurological problems, and organ failure. Tertiary syphilis can be fatal if medical care isn’t sought out immediately (Clement, 2014). A famous example of this gangster Al Capone, who never sought medical treatment after contracting syphilis. The infection ate away at his organs—mostly notably, his brain—and he eventually died. 

Syphilis is caused by a type of bacteria called Treponema pallidum. The infection passes via skin-to-skin contact with lesions during vaginal, anal, or oral sex (Mattei, 2012). 

The bacteria use mucous membranes—found in places like the mouth, genitals, or anus—as a point of entry. You can also get syphilis if any abrasions on your skin connect with a syphilis lesion. An example of this is when a small tear occurs during sex and then touches a lesion (Peeling, 2017).

Syphilis can also pass from someone pregnant to their unborn baby through the placenta. If an infant has syphilis from birth, it’s called congenital syphilis (Peeling, 2017).

Syphilis sounds scary, but the good news is it’s fully treatable. And the treatment for it is pretty simple, too.

A single shot of penicillin into your butt or thigh is the most common treatment for primary and secondary syphilis (Clement, 2014). Advanced syphilis cases may require more intensive medical intervention (Peeling, 2017). 

If your healthcare provider thinks you might have syphilis, they’ll likely order a blood test to diagnose it. After treatment, you can expect to have another blood test to confirm the bacteria is out of your system (Peeling, 2017; Lasagabaster, 2019). If you ever notice symptoms again, you should get retested. Unfortunately, it is possible to get reinfected with syphilis (Clement, 2014). 

See a healthcare provider right away if you think you’ve contracted syphilis so you can get diagnosed and begin treatment right away. 

Syphilis can be tricky since it looks like other conditions and has periods where it shows no symptoms (Tudor, 2021). If you have any telltale signs of syphilis—like sores on your genitals or a non-itchy rash on your hands and feet—get tested right away. If you’ve had close contact with someone diagnosed with syphilis, it’s important to get tested, even if you don’t think you’re infected.

Syphilis won’t go away on its own without treatment, it just goes into hiding. Even with no symptoms, the infection is still dangerous and easily transmitted to others. If you’ve already been diagnosed, treatment is usually one antibiotic shot of penicillin.

You can prevent syphilis by making sure you and any partners get tested regularly. Using condoms during sexual contact also helps. 

While there isn’t currently a vaccine to prevent syphilis, here are a few tips to lower your chances of contracting it:

• Practice safe sex: Use condoms consistently and correctly to reduce your risk of getting syphilis (Workowski, 2015).

• Talk to sexual partners: If syphilis is a concern, chat to your sexual partners about whether they’ve noticed any signs of infection. It’s always a good idea to ask if they’ve been tested recently as well. Both these steps are important as having sex with someone who has syphilis—especially if they have sores or a rash—could get you infected (Nyatsanza, 2016).

• If you’ve had sex with someone diagnosed with syphilis: The first step is visiting a healthcare professional to get tested (usually through a simple blood test). The next step is getting an injection of penicillin, which will help prevent infection or treat one that’s already active (Tudor, 2021).

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Current version

June 21, 2021

Written by

Danielle Oaks

Fact checked by

Yael Cooperman, MD

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About the medical reviewer

Yael Cooperman, MD, Ro

Yael Cooperman is a physician and works as a Senior Manager, Medical Content & Education at Ro.