Syphilis is preventable through a combination of physical barriers, medication, regular testing, and partner communication. No single method eliminates the risk entirely, but layering several strategies together offers strong protection. Here’s what works and how well each approach performs.
Condoms Reduce Risk but Have Limits
Consistent and correct condom use lowers the chance of getting syphilis, but the protection depends on where the sore is located. Syphilis spreads through direct contact with an infectious sore called a chancre, and these sores can appear on areas a condom doesn’t cover: the scrotum, inner thighs, vulva, or around the anus. When the sore happens to be on a part of the genitals that a condom does cover, the barrier works well. When it’s not, transmission can still happen.
The CDC notes that epidemiologic studies show latex condoms provide “limited protection” against syphilis compared to their near-complete protection against HIV. That doesn’t mean condoms aren’t worth using. They remain one of the most accessible tools available and simultaneously protect against multiple other infections. But for syphilis specifically, condoms work best as one layer in a broader prevention plan rather than the only layer.
Doxycycline After Sex (Doxy-PEP)
A newer prevention option involves taking an antibiotic called doxycycline within 72 hours after unprotected sex. The CDC released clinical guidelines for this approach in 2024, and the data behind it is strong: across three large randomized controlled trials, a single 200 mg dose of doxycycline taken after sex reduced syphilis infections by more than 70%.
One trial found a 73% reduction in syphilis risk. Another found the risk dropped by roughly 79%. The maximum dose is 200 mg within any 24-hour period, and it should be taken as soon as possible after oral, vaginal, or anal sex. The current guidelines are based on studies conducted among men who have sex with men and transgender women, so the evidence is strongest for those groups. If you’re in a higher-risk category and have frequent exposures, this is worth discussing with a healthcare provider who can write a prescription you keep on hand.
Fewer Partners and Mutual Monogamy
The math is straightforward: fewer sexual partners means fewer potential exposures. A long-term, mutually monogamous relationship with someone who has tested negative is one of the most effective ways to avoid syphilis entirely. The key word is “mutually,” meaning both partners have been tested and are exclusively seeing each other.
For people who aren’t in monogamous relationships, reducing the overall number of partners still lowers cumulative risk. This doesn’t have to be all-or-nothing. Even modest reductions in the number of new partners over a given period meaningfully decrease your chances of encountering the infection.
Know What a Syphilis Sore Looks Like
Syphilis enters the body through direct contact with an infectious sore, so recognizing one can help you avoid exposure. During the primary stage, the sore is typically firm, round, and painless. It appears at the spot where the bacteria entered the body, which could be the genitals, anus, rectum, or mouth. Because the sore doesn’t hurt, many people don’t notice it on themselves or a partner.
These sores last three to six weeks and heal on their own whether or not the person gets treatment. The healing doesn’t mean the infection is gone. It means the disease has moved to its next stage and the person is still infectious. If you notice a sore like this on a partner, avoiding direct contact with it is the most immediate way to protect yourself. And if you notice one on yourself, getting tested and treated quickly prevents you from passing the infection to others.
Regular Testing Catches What Prevention Misses
Screening is one of the most powerful tools for controlling syphilis at a community level. Because the disease can be painless and easy to miss in its early stages, routine blood tests catch infections that would otherwise go undetected and untreated for months.
The CDC’s screening recommendations vary by risk level:
- Sexually active men who have sex with men: at least once a year, or every three to six months if at increased risk
- People living with HIV: at the first HIV evaluation, then at least annually
- Other adults at increased risk (based on factors like history of incarceration, transactional sex work, geography, or age under 29 for men): periodic screening as risk factors dictate
Testing matters for prevention because syphilis is easily curable in its early stages. A person who finds out they’re positive can get treated and stop transmitting the infection to partners. Every case caught early is a chain of transmission broken.
Screening During Pregnancy
Syphilis can pass from a pregnant person to their baby, causing serious complications including stillbirth, bone deformities, and organ damage. This is called congenital syphilis, and rates have been rising sharply in recent years. The good news is that treatment during pregnancy is highly effective at preventing transmission to the baby.
The U.S. Preventive Services Task Force recommends universal screening for syphilis early in pregnancy. Most states mandate testing at the first prenatal visit. The American College of Obstetricians and Gynecologists goes further, recommending rescreening during the third trimester and again at birth for all pregnant patients. The CDC and other organizations recommend that same third-trimester and delivery rescreening for those at higher risk. If someone doesn’t receive early prenatal care, screening should happen at the first available opportunity, even if that’s at the time of delivery.
Partner Communication and Treatment
If you test positive for syphilis, getting your recent sexual partners tested and treated is essential for stopping the cycle of reinfection. It’s common for people to be treated successfully, then get reinfected by an untreated partner they continue to see. Open conversations about testing status before sex, while uncomfortable, are one of the simplest and most effective prevention tools available.
Unlike with chlamydia or gonorrhea, expedited partner therapy (where a doctor provides medication for a partner without examining them first) is not currently a standard recommendation for syphilis. That means partners need their own medical visit for proper testing and treatment. Encouraging partners to get tested isn’t just courteous. It directly protects your own health by reducing the chance of reinfection.
No Vaccine Exists Yet
There is currently no vaccine for syphilis. Research remains in the pre-clinical phase, meaning scientists are still working to identify the right targets on the bacteria before a vaccine candidate can even enter human trials. This is a long road, and a usable vaccine is likely years away at minimum. In the meantime, the strategies above represent the best available toolkit for staying protected.