What Is Syphilis? Symptoms, Stages, Treatment and Is It Curable?

Written by Dr. Simon Khela MBChB MRCGP, GMC Registered Doctor

Last reviewed: 03-07-2026

If you've searched anything about syphilis, there's a good chance the question underneath all your other questions is: can this actually be cured? It's the single most common thing people ask about this infection, more than symptoms, more than how it's caught — and the short answer is yes, at every stage, syphilis responds to treatment. What matters is catching it before it's had years to cause damage that treatment can't undo.

Syphilis has a strange reputation. It's often talked about as a historical disease, something from old novels and Victorian medicine — but it hasn't gone anywhere, and cases in the UK have actually been rising. Part of the reason it spreads quietly is that its symptoms come and go in a way that convinces people they've recovered, when the infection is still very much present. This guide covers what syphilis is, how it progresses through distinct stages, what to look for, and exactly what treatment involves.

What is syphilis?

Syphilis is a bacterial infection caused by Treponema pallidum, spread primarily through vaginal, anal, and oral sex, or through direct contact with a syphilis sore. Unlike some STIs that stay fairly constant once you have them, syphilis moves through recognisable stages — and the symptoms at each stage look different enough that people often don't connect them to the same underlying infection.

It's entirely curable with antibiotics, at any stage. The important nuance is this: treatment kills the bacteria and stops the infection progressing, but it can't reverse damage that's already been done if syphilis has been left untreated for years. That's the real reason early testing matters — not because it's incurable later, but because some of its long-term effects are.

The stages of syphilis

Syphilis progresses through four stages if left untreated, and understanding them explains why the symptoms can seem to appear, disappear, and then come back completely differently.

Primary syphilis

The first sign is usually a single, firm, round sore called a chancre, appearing at the site where the infection entered the body — the genitals, anus, rectum, or mouth. It typically appears 2–3 weeks after exposure, though this can range from 9 to 90 days. Crucially, it's usually painless, which is exactly why so many people miss it, especially if it develops somewhere internal, like inside the vagina or rectum, where it simply can't be seen. It heals on its own within a few weeks — but the infection doesn't go away with it. This is the first and most dangerous false reassurance syphilis gives people.

Secondary syphilis

Weeks after the chancre heals, a new set of symptoms can appear:

• A rash, often on the palms of the hands and soles of the feet — a genuinely distinctive feature that sets syphilis apart from most other rashes, and usually not itchy
• Fever, fatigue, and swollen lymph nodes
• A sore throat and headaches
• Patchy hair loss
• Wart-like growths in warm, moist areas of the body

Like the chancre before it, these symptoms typically resolve on their own within weeks — the second false reassurance. The infection is still active and can still be passed on during this stage.

Latent syphilis

After secondary symptoms fade, syphilis can enter a latent stage with no symptoms at all, sometimes lasting for years. It's split into early latent (within the first two years of infection) and late latent (beyond two years), a distinction that actually changes how many rounds of treatment are needed. This is the stage responsible for the search "how long can you have syphilis without knowing" — the honest answer is that it can be years, which is exactly why testing rather than symptom-watching is the only reliable way to know your status.

Tertiary syphilis

If syphilis remains untreated for years — sometimes decades — it can progress to a stage capable of serious, lasting damage to the heart, brain, nerves, eyes, and blood vessels. This is genuinely rare today, precisely because it's straightforward to test for and treat long before reaching this point. It's also the stage where syphilis can become fatal, through cardiovascular or neurological complications. Nerve and brain involvement (neurosyphilis) can technically develop at any stage, not only in tertiary disease, which is one reason untreated syphilis is taken seriously even when someone feels otherwise well.

What does syphilis look like? Symptoms in men and women

The bacterium behind syphilis doesn't discriminate by sex, so the underlying symptoms are largely the same in men and women — but where they show up, and how easily they're noticed, differs quite a bit.

In men, the primary-stage chancre most often appears on the penis, where it's usually visible, though sores in the mouth or anus (particularly relevant for men who have sex with men) are just as easy to overlook as anywhere else.

In women, the chancre frequently develops inside the vagina or on the cervix — locations that are essentially invisible without an internal examination. This is a major reason syphilis is picked up later, and more often incidentally, in women than in men, echoing a similar visibility gap to the one seen with gonorrhoea.

Beyond the chancre, secondary-stage symptoms — the rash, fatigue, swollen glands — look and behave identically regardless of sex. If you're trying to identify a sore or rash from a description alone, that's exactly the limitation a photo or written checklist can't get around: a clinical examination and a blood test are the only reliable way to confirm what you're looking at.

Is syphilis curable? Here's what the evidence says

Yes — syphilis is curable with antibiotics at every single stage, including tertiary syphilis. This is worth stating plainly because it's clearly the question weighing on most people who look into this condition.

What treatment cures is the infection itself: the bacteria are eliminated, and the disease stops progressing. What it can't do is reverse structural damage that's already occurred — if tertiary syphilis has already caused heart or nerve damage before treatment starts, that damage may be permanent even after the infection is gone. This is the entire reason "curable" and "reversible" aren't quite the same word when it comes to late-stage syphilis, and why testing early changes the outcome far more than testing eventually.

How is syphilis diagnosed?

Syphilis is diagnosed through:

• A blood test, which checks for antibodies your body produces in response to the infection — this remains the standard, most reliable method
• A swab from an active sore, if one is present, tested directly for the bacteria

One detail worth knowing: certain blood tests can stay positive for years after successful treatment, since they're detecting your immune response rather than active infection. This is completely normal and is why results are always interpreted alongside your history and, where needed, a second type of blood test — not read in isolation.

How is syphilis spread?

Syphilis passes between people through:

• Vaginal, anal, and oral sex
• Direct contact with an active syphilis sore — this is the key detail behind the "can you get syphilis from kissing" question. It isn't transmitted through saliva itself, but if a sore is present in or around the mouth, direct contact with it (including kissing) can pass on the infection. Without an active sore present, casual kissing carries essentially no risk.
• From a pregnant woman to her baby (congenital syphilis), which can cause miscarriage, stillbirth, or serious illness in the newborn if untreated

It is not spread through toilet seats, shared cups, swimming pools, or casual everyday contact — transmission requires direct contact with an infected area or sore.

Syphilis treatment: what to expect

The standard treatment is an injection of penicillin, given into the muscle. For early-stage syphilis (primary, secondary, or early latent), a single injection is often enough. Late latent syphilis, or syphilis of unknown duration, typically needs a series of three weekly injections instead, and neurosyphilis requires a more intensive course, usually delivered in hospital.

For those with a penicillin allergy, doxycycline tablets are the standard alternative — but the course needs to run its full length, typically around 14 days for early-stage syphilis, not the shorter durations sometimes mentioned online. Stopping early is one of the most reliable ways to leave the infection incompletely treated.

After treatment, follow-up blood tests are used to confirm the infection has genuinely cleared, since antibody levels are expected to fall over the following months. Any sexual partners from the relevant period before diagnosis will also need testing, since reinfection from an untreated partner is entirely possible even after successful treatment.

Complications of untreated syphilis

Left untreated over years, syphilis can lead to:

• Cardiovascular damage, including damage to the aorta
• Neurosyphilis — affecting the brain and nervous system, which can cause symptoms resembling dementia, stroke, or vision and hearing loss
• Gummas — soft tissue growths that can affect skin, bone, and organs
• In rare, advanced cases, death, via cardiovascular or neurological complications

This level of complication is genuinely uncommon today, precisely because syphilis is easy to detect and treat long before reaching this stage — but it's the reason a "no symptoms right now" doesn't mean "nothing to worry about," particularly if it's been years since a possible exposure.

Syphilis and pregnancy

Untreated syphilis during pregnancy can pass to the baby, with serious risks including miscarriage, stillbirth, or significant illness after birth. Because of this, syphilis testing is a routine part of antenatal care, and treatment during pregnancy is both safe and strongly recommended if a result comes back positive — this is one condition where prompt action, rather than waiting, makes a measurable difference to outcomes.

Did you know? A brief history

Syphilis's exact origins are still debated by historians and scientists — one theory points to its arrival in Europe following contact with the Americas in the late 15th century, while another suggests related forms existed in Europe earlier. It's also popped up in some unlikely historical footnotes, including long-running speculation about historical figures (Al Capone among them) having lived with the disease. Interesting as trivia, though not something that changes anything about how it's diagnosed or treated today.

When to see a doctor

Get tested if:

• You notice a sore, rash, or unusual skin change, especially around the genitals, anus, or mouth
• A partner has told you they've tested positive for syphilis or another STI
• You've had unprotected sex and haven't been tested recently
• You're pregnant and haven't yet had routine antenatal STI screening
• You've completed treatment and are due a follow-up blood test

Why choose private testing and treatment

At Private Medical Clinic, we offer confidential, private syphilis testing with fast results and treatment available without an NHS waiting list. Every consultation is with a GMC-registered GP, and our online GP consultations let you start the conversation privately if that's more comfortable. We also offer full sexual health screening alongside syphilis testing, covering gonorrhoea, chlamydia, HIV, herpes, and genital warts/HPV, so a single visit covers everything rather than leaving gaps.

Clinics are available across Birmingham, London, Newcastle, Leicester, Oxford, Derby, Sutton Coldfield, and Bournemouth & Dorset. Check current pricing on our fees page, or browse our FAQs if you have questions before booking.

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