This page is general health information, not medical advice. It cannot tell you whether you have an infection. A clinician can, and the testing options on this site are a good place to start.

Syphilis is a bacterial infection that can be found with a blood test and treated by a clinician. It has been rising across the United States, and St. Louis and St. Louis County are part of that picture. This guide covers how syphilis behaves, what syphilis symptoms and the syphilis rash can look like, how testing works, and what to expect from care.

The question many people start with is whether syphilis is curable. In short, yes. The CDC says syphilis can be cured with the right antibiotic from a clinician. The details matter, so they are covered below.

The short version

Syphilis is caused by a bacterium. The CDC STI Treatment Guidelines (2021) describe it as curable with antibiotics prescribed by a clinician.
Many people have mild symptoms or none, so a blood test is the only way to know.
Testing uses two kinds of blood tests. Clinicians often use both.
Follow-up blood tests after treatment show whether the infection is responding.
Free testing is available in the City of St. Louis. Several other clinics offer low-cost or sliding scale care.

The organism behind syphilis

This section replaces the usual ingredient breakdown, because syphilis is an infection and not a product. The cause is a spiral-shaped bacterium called Treponema pallidum. It spreads mainly through direct contact with a syphilis sore during vaginal, anal or oral sex, according to the CDC.

The bacterium can also pass from a pregnant person to a baby. This is called congenital syphilis. It is one reason pregnancy screening matters so much.

Syphilis is not spread by toilet seats, doorknobs, shared dishes or casual contact. Anyone who is sexually active can get it, whatever their gender or orientation. Having it says nothing about a person's character.

The bacterium is hard to grow in a lab. That is why diagnosis relies on blood tests, and sometimes on examining a sore, instead of a simple culture. The blood tests look for the body's response to the bacterium, which is the science behind the two test types described later.

The stages of syphilis

The CDC describes syphilis in stages. Not everyone moves through them in a neat order, and symptoms can be easy to miss. Only a test can tell a person where they stand.

Primary syphilis

The first sign is usually a sore called a chancre. The CDC says it is typically firm, round and painless. It can appear where the bacterium entered the body, including places that are hard to see, such as inside the vagina, rectum or mouth.

The CDC notes that the sore usually appears about 3 weeks after exposure, but it can take anywhere from 10 to 90 days. It heals on its own in a few weeks. Healing does not mean the infection is gone. Without treatment, the infection stays in the body.

Secondary syphilis and the syphilis rash

The syphilis rash is the best-known sign of the second stage. The CDC says the rash can show up as the first sore is healing or several weeks after. It often appears as rough, reddish-brown spots on the palms of the hands and soles of the feet. It can also look different, and it may be faint.

The CDC also notes that the rash usually does not itch. Because it can resemble other skin conditions, it is often mistaken for something else. A clinician can tell the difference, and a blood test can help.

Other secondary syphilis symptoms listed by the CDC include:

Fever and tiredness
Sore throat
Swollen lymph nodes
Patchy hair loss
Headaches and muscle aches
Weight loss
Wart-like patches in warm, moist areas of the body

These signs also go away without treatment. That can be reassuring in the moment, but the CDC says the infection can continue even when symptoms fade.

Latent syphilis

In the latent stage there are no signs or symptoms. The infection is still present, and it is found only through a blood test. The CDC divides this stage into early and late latent syphilis based on how long ago the infection was acquired, and a clinician may need to take a history to decide.

Tertiary syphilis and later complications

The CDC says that without treatment, a small share of people go on to develop tertiary syphilis. This can happen years or even decades later. It can affect the heart, blood vessels and brain, among other organs.

The infection can also reach the nervous system, the eyes or the ears at any stage. These are called neurosyphilis, ocular syphilis and otosyphilis. Symptoms can include severe headache, vision changes, hearing changes or dizziness. Anyone with these symptoms should be seen promptly by a clinician and should mention any possible syphilis exposure.

Why the national rise matters

The CDC's national surveillance report for 2022 recorded more than 200,000 total syphilis cases, the highest number reported since the 1950s. The same report showed congenital syphilis climbing about 31 percent in a single year. Check the CDC's STI surveillance pages for its latest figures.

This matters for a plain reason. Syphilis is treatable, but it is often found late because early symptoms are mild or missed. More cases in a community means more chances for a missed infection to pass on or to reach a pregnancy.

Rising numbers are not a reason to feel alarmed. They are a reason for routine testing to feel ordinary, like any other check-up.

Syphilis in St. Louis and Missouri

Local data helps explain why testing is encouraged here. The City of St. Louis is an independent city, so the City of St. Louis Department of Health and the St. Louis County Department of Public Health are separate agencies.

The City of St. Louis Department of Health reported 10 congenital syphilis cases in the city in 2020, up from 5 in 2019. For St. Louis County it reported 4 cases in 2020, or 3.8 per 10,000 live births (City of St. Louis Department of Health news release, April 2022).
The same release said syphilis incidence in the city did not change significantly from 2019 to 2020. In St. Louis County, gonorrhea and syphilis rates were up 13 percent over the same period.
The City of St. Louis Department of Health reports that 56 congenital syphilis cases were reported in St. Louis County and the city combined from 2020 through 2022.

These numbers come from the health department and are several years old. The department's news page and the CDC are the places to look for newer figures. Reported counts also depend on how many people get tested, so they are best read as a rough signal and not a full count.

How syphilis testing works

A blood draw is the most common way to test, as described in the CDC STI Treatment Guidelines (2021). Some sites also offer a finger-prick option. If a person has a sore, a clinician may look at it directly and may collect a sample from it as well.

Non-treponemal tests

These tests, such as the RPR and VDRL, look for substances the body makes in response to damaged cells. The CDC says they are useful for two reasons. They can be reported as a number (a titer), and that number can be compared over time to see how the infection responds to treatment.

They can sometimes give a false positive result because of other conditions. That is one reason a second kind of test is used.

Treponemal tests

These tests, such as the TP-PA, look for antibodies aimed at the syphilis bacterium itself. According to the CDC, they usually stay reactive for life, even after successful treatment. That is why they confirm that a person has been exposed at some point, but they are not used to track treatment.

Why two tests are used

The CDC guidelines describe using both kinds of test together to reach a result. Labs may run them in either order. If a person is told one test was reactive and the other was not, that does not necessarily mean a mistake. It means the clinician may order more testing or ask more questions.

Timing after a possible exposure

Blood tests can be negative very early after an exposure. For syphilis, the CDC does not give one fixed window period for every test. Instead, it notes that incubation ranges from about 10 to 90 days. The CDC guidelines also say that a person exposed within the past 90 days to a partner with early syphilis may be treated by a clinician even before test results are back.

If a recent exposure is on your mind, tell the clinic when it happened. They can advise when testing and any repeat testing make sense.

Who should be tested

The U.S. Preventive Services Task Force recommends syphilis screening for adolescents and adults who are at increased risk, and for all pregnant people. The CDC adds that people with a partner who has syphilis, people living with HIV, and people taking HIV PrEP should be screened regularly. A clinician can help you decide how often.

Is syphilis curable? Treatment from a clinician

Yes. The CDC says syphilis is curable. Treatment is a prescription decision made by a clinician. The CDC guidelines name penicillin as the preferred medicine for every stage. Early syphilis is usually treated with a single type of penicillin injection, while later stages may need a longer course. Your clinician decides the exact plan.

Treatment stops the infection and prevents further damage. It may not reverse harm that has already happened in the later stages, which is another reason earlier testing helps.

Do not try to treat syphilis with leftover or borrowed antibiotics. The wrong medicine or the wrong course can hide symptoms without clearing the infection. Only a clinician can choose the right treatment.

Treatment and sex partners

Recent partners may need testing and possibly treatment, even if they feel well. The health department or clinic can explain how to let partners know, including options that do not share your name. According to the CDC, Missouri's expedited partner therapy law (RSMo 191.648) covers chlamydia and gonorrhea, not syphilis. For syphilis, partners generally need to be seen by a clinician.

Safety profile and extra considerations

Research on penicillin for syphilis spans many decades, and the CDC continues to rely on it. Even so, a few points are worth knowing.

Penicillin allergy

Many people who think they are allergic to penicillin are not. Tell your clinician about any past reaction. The CDC guidelines say that for most non-pregnant people with a true allergy, a clinician may choose another antibiotic. For pregnancy, the CDC guidelines say penicillin is the recommended treatment, and a clinician may work with an allergy specialist if needed.

A short-lived reaction after treatment

The CDC describes a reaction called Jarisch-Herxheimer that can happen within about a day of treatment. It can include fever, chills, headache and muscle aches. It usually passes on its own. Ask your clinic what to do if it happens and when to call.

Pregnancy

Syphilis in pregnancy can lead to serious outcomes for a baby, including stillbirth, according to the CDC. Treatment during pregnancy can prevent congenital syphilis. The USPSTF recommends that all pregnant people be screened for syphilis early in pregnancy.

Missouri law (RSMo 210.030, Missouri Revisor of Statutes) directs prenatal care providers, with the patient's consent, to test a blood sample for syphilis, hepatitis B, hepatitis C and HIV at the first prenatal visit or soon after. The statute also describes later testing. A 2025 House bill proposes to amend that section, so ask your provider or check the current statute for the exact timing.

Living with HIV

Syphilis and HIV can affect each other. The CDC recommends regular syphilis screening for people living with HIV. HIV is not curable, but it is treatable and manageable with medicine from a clinician. Syphilis is treated the same way, with attention from your care team to follow-up.

Doxy-PEP

In 2024 the CDC issued guidance on doxycycline taken after sex (doxy-PEP). The guidance applies to gay, bisexual and other men who have sex with men, and to transgender women, who have had a bacterial STI in the past year. Research suggests it can lower the chance of syphilis, chlamydia and gonorrhea. It is a prescription decision, and a clinician can explain who it may help and what to watch for. WashU Infectious Diseases lists doxy-PEP among the services at its Village Square Clinic.

After treatment: follow-up blood tests

Follow-up testing is part of care. The CDC guidelines describe repeat non-treponemal blood tests at set intervals after treatment. For many people, this means checks over the first year or two. The exact timing depends on the stage and on whether a person also lives with HIV.

The goal is to see the titer fall. The CDC guidelines say a clear drop in the number suggests treatment is working. A treponemal test usually stays reactive for life, so a clinician will not use it to measure cure.

If the number does not drop as expected, the clinician may look into it further, check for a new exposure, or consider more treatment. Reinfection is possible. Having had syphilis does not protect someone from getting it again, so testing remains useful with new or ongoing partners.

Avoiding sex until treatment is complete and any sores have healed is the standard advice from the CDC. Your clinic will tell you when that applies.

Quality indicators: how to choose reliable care in St. Louis

Instead of sourcing a product, the useful question here is how to spot good care. Look for these signs:

The clinic is run by a health department, a community health center or a hospital-affiliated program.
They test for syphilis with a blood test and can explain which tests they use.
They keep results confidential and talk through treatment and follow-up.
They are open about cost, or say plainly when a price is not posted.

The CDC's GetTested directory at gettested.cdc.gov lets you look up sites by ZIP code. Each listing is a starting point, and calling ahead is wise because hours and walk-in rules can change.

Where to get tested in St. Louis

Here is what is published for places that offer testing. For a wider list with costs, see our guide to STD testing in St. Louis, or browse the local testing list.

City of St. Louis Health Stop Testing and Referral Center

Address: 1520 Market St, Suite 1625 (first floor), St. Louis, MO 63103
Phone: 314-657-1584
Cost: The City of St. Louis page says there is no cost and no ID is necessary.
Hours: Monday to Thursday, 9 a.m. to 12 p.m. and 1 p.m. to 4 p.m. Closed Fridays and city holidays. Walk-ins depend on availability.
Tests listed: syphilis (blood or finger-prick), gonorrhea and chlamydia, HIV and hepatitis C. STI results take 5 to 7 business days, and rapid tests take about 15 minutes.

The CDC's GetTested listing for this site says an appointment is required, which differs from the city's page. Call ahead to confirm. The city page does not state whether treatment is offered there, so ask when you call. The page also lists free HIV self-test kits.

Saint Louis County Sexual Health Clinic

This clinic is at 4000 Jennings Station Road, St. Louis, MO, phone 314-615-9736. WashU Infectious Diseases lists it as walk-in only, with no appointments, and says everyone is welcome regardless of where they live or their insurance. Services listed are STI prevention, testing and treatment. The listing does not give hours or prices, so call to check both.

WashU Infectious Diseases, Village Square Clinic

This clinic is at 1 Village Square Shopping Center, Suite 1, Hazelwood, MO 63042, phone 314-362-9098. A May 2024 WashU news article described a CDC-funded expansion meant to offer walk-in testing at no or low cost, with treatment for walk-in patients and their partners. Service details were still being worked out when it was written, so confirm by phone, including hours.

Planned Parenthood Great Rivers, Central West End Health Center

Located at 4251 Forest Park Ave, Saint Louis, MO 63108, phone 314-531-7526. The CDC GetTested listing shows tests for syphilis, chlamydia, gonorrhea, herpes and HIV, a sliding scale, and that an appointment is required. Hours are not listed there.

CareSTL Health, Dr. Martin Luther King Health Center

Located at 5471 Dr Martin Luther King Dr, Saint Louis, MO 63112, phone 314-367-5820. The CDC listing shows syphilis, chlamydia, gonorrhea and HIV blood tests, insurance, Medicaid, Medicare and a sliding scale, and that an appointment is required. Hours are not listed there.

Saint Louis County Department of Public Health, John C. Murphy Health Center

This center is at 6121 N Hanley Rd, Berkeley, MO 63134, phone 314-615-0500. The CDC listing shows a sliding scale and vaccines, but it did not show STI test types, so call to ask what is offered.

Your rights and privacy in Missouri

Under Missouri law (RSMo 431.061, Missouri Revisor of Statutes), a minor may consent to treatment for venereal disease. The statute states no minimum age. If you are under 18, you can ask a clinic how it handles privacy and billing.

Missouri also has a law (RSMo 191.677) about knowingly exposing another person to a serious infectious or communicable disease. The statute does not name syphilis or HIV specifically. If you have questions about how it could apply to you, a legal aid service or attorney is the right person to ask. A clinician cannot give legal advice.

What to bring up at your visit

Any sore, rash or other change you have noticed, and when it started.
The timing of any recent exposure.
Past penicillin reactions.
Whether you are pregnant or could become pregnant.
Your HIV status, and whether you use or want PrEP.

You do not need to explain or justify anything. Clinicians at these sites see people of every background every day.

The bottom line

Syphilis is common enough in St. Louis that routine testing makes sense, and it can be cured with treatment from a clinician. The rash and sores can be easy to miss, so a blood test is the reliable way to find out. If you want to get tested, start with the City of St. Louis Health Stop, which lists free syphilis testing, or use gettested.cdc.gov to find a site near you. Call ahead to confirm hours.

Syphilis in St. Louis: Symptoms, Testing and Treatment