What Is Syphilis? Symptoms, Stages, Testing, and Treatment Explained (2026 Guide)

4 days ago

11 min read

Updated: 2 days ago

Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: September 2026

Editorial note: This article is based exclusively on authoritative medical sources, including Mayo Clinic (pages updated September 10, 2024) and CDC surveillance data. It is for general education only and is not medical advice. If you suspect you have been exposed to syphilis, see a healthcare professional for testing — early syphilis is easily curable.

TL;DR

Syphilis is a bacterial infection caused by Treponema pallidum that spreads mainly through sexual contact with an infected sore. It progresses through stages — primary (painless sore), secondary (non-itchy rash, often on palms and soles), latent (no symptoms for years), and tertiary (organ damage in up to 40% of untreated people). Early syphilis is curable, often with a single penicillin shot, which is why prompt testing matters so much. U.S. syphilis cases reached their highest level since the 1950s in 2022 (207,623 cases) and have stayed at record highs since.

Quick Answer: What is syphilis and is it curable?

Syphilis is a curable bacterial infection spread primarily through sexual contact with an infected sore. It develops in stages — starting with a painless chancre, then a rash, then years of silent infection, and potentially severe organ damage. Penicillin cures it at every stage, and early syphilis often requires just one injection. Testing is the critical step, because the painless early sore is easy to miss.

What is syphilis?

Syphilis is an infection caused by the bacterium Treponema pallidum. It most often spreads through sexual contact and typically starts as a sore that is usually painless, appearing on the genitals, rectum, or mouth. The bacteria enter the body through minor cuts or scrapes in the skin, or through the moist inner lining of body parts.

The infection can remain dormant in the body for years without causing symptoms — and then become active again. Without treatment, syphilis can damage the heart, brain, eyes, and other organs, and can become life-threatening. It can also be passed to a baby during pregnancy and childbirth, and sometimes through breastfeeding.

The encouraging news: early syphilis is curable, sometimes with a single shot of penicillin. Once cured, syphilis does not come back on its own — though reinfection is possible after new exposure.

What are the symptoms of syphilis?

Syphilis develops in stages, and symptoms vary with each stage. The stages may overlap, and symptoms do not always occur in the same order. You can carry the bacteria for years without noticing any symptoms at all.

| Stage | Key symptoms | Typical timing | |---|---|---| | Primary | Painless sore (chancre) at the site where bacteria entered — genitals, rectum, tongue, or lips; usually a single sore, sometimes more | Chancre appears about 3 weeks after exposure; heals on its own in 3–6 weeks | | Secondary | Non-itchy rough red or reddish-brown rash (often starts on trunk, later palms of hands and soles of feet); wartlike sores in mouth or genital area; hair loss; muscle aches; fever; sore throat; fatigue; weight loss; swollen lymph nodes | Begins as the chancre heals or weeks after | | Latent | No symptoms at all ("hidden stage") | Can last for years | | Tertiary (late) | Damage to brain, nerves, eyes, heart, blood vessels, liver, bones, and joints | May occur many years after the untreated infection; affects up to 30–40% of untreated people |

At any stage, untreated syphilis can spread to the brain, spinal cord, eyes, and other body parts, causing serious or life-threatening problems.

Primary syphilis: the sore you might miss

The first sign is a small sore called a chancre (pronounced SHANG-kur). Because it is usually painless — and may be hidden inside the vagina or rectum — many people never notice it. It heals on its own within 3 to 6 weeks, which can create a false sense that the problem has gone away. In fact, the infection is simply entering its next stage.

Secondary syphilis: the rash that doesn't itch

The syphilis rash is frequently so faint that it is hard to see. It may look rough, red, or reddish-brown, often starts on the trunk (chest, stomach, pelvis, back), and can later appear on the limbs, palms of the hands, and soles of the feet. Symptoms of secondary syphilis may disappear on their own — but without treatment they can come and go for months or years.

How common is syphilis?

Syphilis has been rising sharply in the United States for more than two decades, and recent CDC surveillance data puts the trend in clear context.

| Statistic | Figure | Source | |---|---|---| | U.S. syphilis cases in 2023 | 209,253 (highest annual total ever recorded) | CDC STI Surveillance 2023 | | Growth 2018 → 2022 | +80% (115,045 → 207,623 cases) | CDC STI Surveillance Report 2022 | | Congenital syphilis cases, 2023 | 3,882, including 279 stillbirths and neonatal/infant deaths | CDC STI Surveillance 2023 | | Newborn syphilis trend | 12th consecutive year of increase in 2024, up roughly 700% since 2015 | CDC (Sept. 24, 2025) |

Because the early sore is painless and the rash can be faint, many infections go unnoticed — which is exactly how the bacterium keeps spreading. This is why CDC guidance recommends that all pregnant people be tested for syphilis at their first prenatal visit.

What causes syphilis?

The cause is the bacterium Treponema pallidum. The most common transmission route is contact with an infected person's sore during vaginal, oral, or anal sex. The bacteria enter the body through minor cuts or scrapes in the skin, or through the moist inner lining of some body parts.

Syphilis is contagious during its primary and secondary stages, and sometimes during the early latent period (within one year of infection). Less often, it can spread by kissing or touching an active sore on the lips, tongue, mouth, breasts, or genitals.

Importantly, syphilis cannot be spread through casual contact with objects. You cannot catch it from a toilet, bathtub, clothing, eating utensils, doorknobs, swimming pools, or hot tubs.

Who is at higher risk?

The risk of catching syphilis is higher if you have unprotected sex, have sex with more than one partner, or live with HIV. CDC also reports elevated rates among men who have sex with men, linked in part to differences in healthcare access, condom use, and recent sex with partners found through social media apps.

Syphilis sores on the genitals also raise the risk of catching or spreading HIV, because a syphilis sore can bleed easily and provide an entry point for HIV during sex.

What happens without treatment?

Without treatment, syphilis can cause damage throughout the body — and treatment can prevent new damage but cannot repair or reverse damage that has already happened. The potential complications include:

| Complication | What it involves | |---|---| | Gummas | Rare late-stage bumps or growths on skin, bones, liver, or other organs; usually resolve with antibiotics | | Neurological | Headache, stroke, meningitis, confusion, dementia-like memory and judgment loss, paralysis, erectile dysfunction, bladder problems | | Ocular (eyes) | Eye pain or redness, vision changes, blindness | | Otosyphilis (ears) | Hearing loss, tinnitus (ringing in the ears), vertigo | | Heart and blood vessels | Bulging and swelling of the aorta and other blood vessels; heart valve damage | | HIV risk | Genital sores raise the chance of catching or spreading HIV during sex | | Pregnancy | Miscarriage, stillbirth, or newborn death within days of birth |

Congenital syphilis

Pregnant people with syphilis can pass the infection to their babies through the placenta or during birth. Newborns might have no symptoms, but without fast treatment they can develop skin sores and rashes, fever, jaundice, anemia, a swollen spleen and liver, rhinitis (sneezing or a drippy nose), and bone changes. Later symptoms may include deafness, teeth problems, and saddle nose (collapse of the bridge of the nose). Babies can also be born too early, die before birth, or die after birth.

How congenital syphilis spreads, its effects on newborns, and how prevention works.

How is syphilis diagnosed?

You may be able to use a non-prescription at-home test to check for syphilis. If it shows syphilis, you still need to see a healthcare professional to confirm the diagnosis and start treatment.

Healthcare teams confirm syphilis by testing:

| Test | What it shows | |---|---| | Blood test | Antibodies the immune system makes against the bacteria; antibodies stay in the body for years, so blood tests can detect current or past infection | | Fluid from a sore | Laboratory microscopy can confirm syphilis caused the sore | | Lumbar puncture (spinal tap) | If nervous system involvement is suspected, cerebrospinal fluid is tested |

Your local health department may also offer free partner services that help you notify sexual partners privately, so they can be tested and treated, limiting further spread.

How is syphilis treated?

Syphilis is straightforward to cure when found and treated early. Penicillin is the preferred treatment at all stages, and this antibiotic kills the bacteria that causes syphilis.

| Situation | Treatment approach | |---|---| | Primary, secondary, or early latent syphilis | A single shot of penicillin | | Infection longer than one year | Additional penicillin doses may be needed | | Penicillin allergy (non-pregnant) | Another antibiotic may be suggested, or desensitization | | Pregnancy (any stage) | Penicillin is the only recommended treatment; allergic patients undergo penicillin desensitization (~4 hours with tiny doses every 15–20 minutes, done by an allergist/immunologist) |

What is the Jarisch-Herxheimer reaction?

On the first day of treatment, some people experience a Jarisch-Herxheimer reaction — symptoms that include fever, chills, nausea, achy pain, and a headache. Most often this reaction lasts no more than one day.

After treatment

After treatment, your care team will likely ask you to have regular blood tests and exams to confirm the penicillin is working, avoid sexual contact with new partners until treatment is finished and blood tests show the infection is cured, tell your sex partners so they can be tested, and get tested for HIV. Even newborns of treated pregnant patients should be tested for congenital syphilis; infected babies receive antibiotic treatment.

Syphilis treatment guide infographic: penicillin at every stage, single injection for early syphilis, pregnancy treatment, and after-treatment checklist

Syphilis treatment with penicillin: what to expect at every stage, including pregnancy.

How can syphilis be prevented?

There is no vaccine for syphilis. Prevention relies on behavior and testing:

| Prevention measure | How it helps | |---|---| | Abstinence or safer sex | The only certain avoidance; safer sex means a long-term mutually monogamous relationship in which neither partner is infected — both partners should test before sex with someone new | | Latex condoms | Lower the risk, but only if they cover the infected sores; other birth control does not lower syphilis risk | | Avoid alcohol/drug impairment | Excessive drinking or drug use can lead to unsafe sex | | Avoid douching | Removes healthy vaginal bacteria and may raise STI risk | | Breastfeeding caution | Syphilis can pass if sores are on a breast or a pump touches a sore; pump or hand-express until sores heal, and discard milk if the pump contacted a sore | | Doxycycline post-exposure prophylaxis | For higher-risk groups (including men who have sex with men and transgender women), taking doxycycline within 72 hours of sex can lower the risk of infection, per CDC's 2024 guideline; a professional prescribes it and provides testing while you take it | | Prenatal screening | All pregnant people should be tested at their first prenatal checkup |

Partner notification

If you test positive, partners from the past three months to one year need to know so they can get tested and treated. Health departments offer a free, confidential partner notification service that contacts partners without revealing your identity. Because syphilis can be caught more than once, partner notification also lowers your own risk of reinfection.

Why early testing matters

The painless chancre and faint rash mean syphilis can hide for years — while remaining transmissible and building toward permanent damage. But the other side of that equation is equally important: early syphilis is curable, sometimes with a single injection. Testing turns a potentially life-threatening infection into a simple, decades-old cure.

Four-stage timeline of syphilis: primary chancre, secondary rash, latent stage, tertiary organ damage

The four stages of syphilis, from the primary chancre to tertiary organ damage.

When should you see a doctor?

Contact a healthcare professional if you or your child has any symptoms of syphilis — any unusual discharge, sore, or rash, especially in the groin area. Get tested for syphilis if you have had sexual contact with someone who might have the disease, have another STI such as HIV, are pregnant, regularly have sex with more than one partner, or have unprotected sex (sex without a condom).

If you think you might have syphilis, avoid sexual contact until you have talked with your healthcare team. If you have sex before the appointment, use safe-sex practices such as condoms.

Conclusion and next steps

Syphilis is one of medicine's clearest success stories in one direction and its clearest warning in the other. The bacterium is fully curable with penicillin at every stage — yet U.S. cases have hit the highest levels since the 1950s, and congenital syphilis has risen for twelve straight years, largely because early symptoms are easy to miss.

Your next steps: If you've had a possible exposure, get tested now — many labs and health departments offer fast, affordable syphilis screening. If you're pregnant, confirm you've been screened at your first prenatal visit. If you test positive, tell your partners and complete the full treatment and follow-up; if you test negative, keep practicing safer sex and get re-screened regularly if you have ongoing risk factors. If you've been cured, remember that reinfection is possible after new exposure — so one test does not make you immune for life.

This article is for educational purposes only and does not replace professional medical advice, diagnosis, or treatment. Always consult a qualified health care provider for decisions about your health.

Frequently Asked Questions

1. Is syphilis curable? Yes. Penicillin cures syphilis at every stage, and early syphilis often requires just a single injection. However, treatment prevents new damage — it cannot reverse damage that already occurred.

2. What does a syphilis sore look like? The primary sore (chancre) is usually small, firm, round, and painless. Because it doesn't hurt — and may be hidden inside the vagina or rectum — many people never notice it. It heals on its own in 3 to 6 weeks.

3. Can syphilis spread through casual contact like toilets or towels? No. Syphilis cannot be spread by casual contact with objects. You cannot catch it from toilets, bathtubs, clothing, eating utensils, doorknobs, swimming pools, or hot tubs.

4. How long can syphilis stay in your body without symptoms? Years. After the secondary stage, untreated syphilis enters a latent ("hidden") stage with no symptoms at all. Without treatment it may never return — or it may cause severe organ damage decades later.

5. Can a syphilis blood test show a past infection? Yes. Antibodies against the syphilis bacterium stay in the body for years, so blood tests can detect both current and past infection. That's why positive at-home tests always need professional confirmation and staging.

6. What happens if syphilis is left untreated? Up to 30–40% of untreated people develop tertiary (late) syphilis, which can damage the brain, nerves, eyes, heart, blood vessels, liver, and bones. It can cause stroke, dementia-like symptoms, blindness, hearing loss, aortic swelling, and death.

7. Can pregnant people with syphilis pass it to their baby? Yes — through the placenta, during birth, and sometimes through breastfeeding if there are sores on the breast. That's why CDC recommends testing all pregnant people at their first prenatal visit, and why penicillin is the only recommended treatment during pregnancy.

8. How soon after sex should I get tested for syphilis? The chancre typically appears about three weeks after exposure, but timing varies. If you've had a possible exposure, see a healthcare professional — they can test and interpret results correctly, and retest later if the timing is too early for antibodies to show.