Syphilis is a bacterial sexually transmitted infection that progresses in stages, and syphilis symptoms change at each one. Early signs are often a single painless sore, followed weeks later by a rash. Without treatment the infection can stay silent for years before causing serious damage, but it is curable with antibiotics.
Caused by the bacterium Treponema pallidum, syphilis spreads through direct contact with a syphilis sore during oral, anal, or vaginal sex, and can also pass from a pregnant person to their baby. Because symptoms come and go and can mimic other conditions, syphilis is sometimes called "the great imitator." Testing is the only reliable way to know your status.
The four stages of syphilis
Syphilis develops in stages. Symptoms can overlap, and stages may not always appear in a clear sequence, which is why a clinical diagnosis matters.
Primary stage
The first sign is typically a single sore called a chancre, though some people develop several.
- Usually firm, round, and painless
- Appears where the bacteria entered the body, often the genitals, anus, rectum, lips, or mouth
- Generally develops about three weeks after exposure
- Heals on its own within 3 to 6 weeks, whether or not you receive treatment
Because the sore is painless and may be hidden, it is easy to miss. Healing does not mean the infection has cleared.
Secondary stage
Weeks after the chancre heals, secondary symptoms can appear. According to the CDC, these may include:
- A non-itchy skin rash, classically on the palms of the hands and soles of the feet
- Mucous membrane sores in the mouth, vagina, or anus
- Fever, swollen lymph glands, and sore throat
- Patchy hair loss, headaches, weight loss, muscle aches, and fatigue
These symptoms also fade on their own, but the infection remains active in the body.
Latent stage
The latent (hidden) stage has no visible signs or symptoms. The WHO notes that without treatment a person can carry the infection for years while it quietly progresses.
Tertiary stage
Tertiary syphilis is uncommon today but very serious. It can develop years to decades after the original infection if it is never treated, and may damage the heart, blood vessels, brain, and nerves. At any stage, syphilis can affect the nervous system (neurosyphilis) or the eyes (ocular syphilis), which can cause headaches, vision changes, or other neurological symptoms.
How syphilis is diagnosed
A blood test is the main way to diagnose syphilis; in some cases a clinician may also test fluid from a sore. Because tests may not be accurate immediately after exposure, providers often recommend testing a few weeks after possible contact and may repeat it later.
- Syphilis is frequently included in a full STI screen
- Testing is confidential and widely available at sexual health clinics and many primary care settings
- A reactive screening test is followed by a confirmatory test
For more on timing and what to expect, see our STI testing guide and our explainer on how long STIs take to show up.
How syphilis is treated
The good news: syphilis is curable with antibiotics, and treatment is most effective when started early.
- The first-line treatment for most stages is an injection of benzathine penicillin, as recommended by the WHO.
- People with a penicillin allergy may be offered alternative antibiotics by a clinician; pregnant people are generally treated with penicillin under medical supervision.
- Follow-up blood tests confirm the treatment worked, and providers usually advise avoiding sexual contact until treatment is complete and follow-up is cleared.
Treatment cures the infection, but it does not reverse damage already done in late stages and does not protect against catching syphilis again. Sexual partners should also be notified and tested.
Lowering your risk
You can reduce your chance of getting or passing on syphilis with steps that apply to most STIs:
- Use condoms or dental dams consistently and correctly (they reduce but do not fully eliminate risk, since sores can occur outside the covered area)
- Get tested regularly, especially with new or multiple partners
- Talk openly with partners about testing and status
- If pregnant, get screened, since untreated syphilis can seriously harm a baby
Our guide to preventing STIs covers these strategies in more detail.
The bottom line
Syphilis symptoms change as the infection moves through its primary, secondary, latent, and tertiary stages, and the early sore and rash can both fade on their own while the infection continues silently. The only way to know your status is testing, and early antibiotic treatment reliably cures it while preventing serious long-term harm. If you notice a sore or rash or think you may have been exposed, talk to a healthcare provider. To learn how testing fits into the bigger picture, start with our STIs and testing hub.
