A syphilis chancre is the first sore of syphilis: a single, firm, round, painless ulcer that appears at the spot where Treponema pallidum bacteria entered the body — usually the genitals, anus, or mouth — about three weeks after exposure. It heals on its own in roughly three to six weeks, but the healing doesn't mean you're cured.
~3 wks; 10–90 days
by stage
| Item | Value |
|---|---|
| Primary sore | painless — ~3 wks; 10–90 days |
| Testing | 2 blood tests |
| Treatment | penicillin — by stage |
| Symptoms fade | ≠ cured |
What a syphilis chancre looks and feels like
The chancre marks the primary stage of infection. Most people develop one sore, though more than one can appear, and it forms exactly where the bacteria broke through skin or mucous membrane. The classic description is a firm, round ulcer with raised edges and a clean base, and it doesn't hurt CDC.
That painlessness is the whole problem. A sore that itches or burns sends you to a doctor; a sore that feels like nothing gets ignored, especially when it sits somewhere you can't easily see. The chancre then heals with or without treatment over three to six weeks. It looks like the body fixing itself, but the bacteria have simply moved deeper and the infection rolls on toward the secondary stage.
You may also notice firm, swollen lymph nodes near the sore, the body's local immune response to the bacteria. The chancre itself is firm to the touch, almost cartilage-like at the edge, which helps distinguish it from softer, more painful ulcers.
Where chancres show up — including the spots people miss
The sore appears at the point of contact, so its location follows the type of exposure:
- On the penis, where it's usually visible.
- Inside or around the vagina or on the cervix, where it can be completely hidden from view.
- In or around the anus and rectum, often mistaken for irritation or a hemorrhoid.
- On the lips, tongue, or inside the mouth and throat after oral contact.
Because the chancre is painless and frequently sits in a place you can't inspect — the cervix, the rectal wall, the back of the throat — it's entirely possible to carry the primary sore and never know it existed. That's why early syphilis so often goes undiagnosed.
How soon a chancre appears after exposure
The chancre typically shows up about three weeks after exposure, but the incubation period runs anywhere from 10 to 90 days. That wide window matters in two ways. A sore appearing a month or two after a single encounter can still be the first sign of syphilis, and a syphilis blood test taken too soon after exposure can come back negative even when you're infected. If your risk was recent, plan to retest — our guide on when to test after exposure explains the timing.
What people mistake a chancre for
The two conditions most often confused with a chancre are herpes and ordinary skin irritation. A herpes outbreak usually produces a cluster of small, painful blisters that ulcerate and burn, close to the opposite of the single, painless, firm syphilis sore. The contrast is detailed in our breakdown of syphilis vs herpes.
Genital chancres also get written off as an ingrown hair, a friction sore, a pimple, or — for rectal lesions — a hemorrhoid or anal fissure. Oral chancres get blamed on canker sores or a bite injury. Any of these explanations can feel reasonable, and since the sore disappears on its own, the wrong explanation never gets corrected. When a firm, painless ulcer shows up after a new sexual partner, syphilis belongs on the list regardless of how harmless it looks.
What happens if a chancre is ignored
Letting the sore heal untreated doesn't end the infection; it advances it. The CDC is blunt: the symptoms go away whether or not you get treated, and without the right antibiotics the infection moves to the latent and possibly tertiary stages. Here's the progression:
- Secondary stage: a rough red or reddish-brown rash, classically on the palms and soles, often with sores on mucous membranes, plus fever, swollen lymph nodes, sore throat, patchy hair loss, headache, muscle aches, and fatigue. These signs also fade on their own without clearing the infection.
- Latent stage: no symptoms at all, sometimes for years, while the bacteria persist in the body and remain detectable on a blood test.
- Tertiary stage: in untreated cases this can strike 10 to 30 years later (sometimes sooner), damaging the heart, blood vessels, brain, and nervous system, and it can be fatal.
Two complications can occur at any stage, not just late: neurosyphilis (invasion of the brain and nervous system, causing headaches, confusion, or paralysis) and ocular syphilis (involvement of the eye that can threaten vision) CDC. New vision changes or neurological symptoms in anyone with syphilis are a medical emergency. In pregnancy, untreated infection passes to the baby in 50 to 80% of cases — causing stillbirth, prematurity, newborn death, or congenital infection — and having syphilis roughly doubles the risk of catching HIV StatPearls.
This isn't a rare-disease scenario. The CDC counted about 53,000 primary-and-secondary cases in 2023, and congenital syphilis nearly doubled in four years, rising from 2,163 cases in 2020 to 3,882 in 2023, its highest level in decades CDC AtlasPlus, 2023. The disease is uneven across the country, with the highest primary-and-secondary rates in South Dakota, Washington DC, New Mexico, and Mississippi.
Who should get screened
Because the first sore is so easy to miss, routine screening catches infections people never noticed. The U.S. Preventive Services Task Force gives syphilis screening its strongest recommendation in two groups:
- All pregnant people — a Grade A recommendation for early, universal screening regardless of risk, with screening at the first opportunity (even at delivery) if it wasn't done earlier USPSTF.
- Nonpregnant adolescents and adults at increased risk — also Grade A, covering men who have sex with men, people with HIV or other STIs, those with a history of incarceration or sex work, and people in high-prevalence communities USPSTF, 2022.
If you fall into a higher-risk group, regular testing matters even when you feel fine, since that's exactly when a hidden, healed chancre would otherwise slip by. Reducing exposure in the first place is its own strategy; see our guide on how to prevent syphilis.
How a chancre is tested and treated
Diagnosis is a simple blood draw, and it takes two tests — a screening test plus a confirmatory one — to call it syphilis CDC, 2024. A test done too soon after exposure can read negative, so retesting is part of the process when the risk was recent. For the full how-to, see our testing page or simply get tested.
Treatment is penicillin G given by injection, and it cures every stage; the schedule follows the stage of disease. We keep full regimens and doses on the treatment guide rather than here. Penicillin remains the only reliable cure, with no dependable oral substitute. Cure is confirmed by falling blood titers over months, not by the sore disappearing, and you can be reinfected, so a past cure offers no future immunity (more on can you get syphilis again after treatment?).
When to see a clinician
See a clinician promptly if you notice a firm, painless sore anywhere on the genitals, anus, or mouth, especially after a new partner, even if it's already healing. Get evaluated if you develop a rash on the palms or soles, unexplained fever with swollen glands, or patchy hair loss. Seek emergency care for new vision changes or neurological symptoms if you have or may have syphilis. And if you're pregnant, ask specifically about syphilis screening at your first prenatal visit.