Can you have Syphilis and not know it?

Yes, and it’s common. The NHS says the symptoms of Syphilis are often mild and hard to notice when you’re first infected.

The first sign is usually a small sore where the bacteria entered the body. It’s typically painless, so if it’s inside the vagina, bottom or mouth, you may never see it. Later symptoms, such as a rash, can come and go. Even when symptoms clear up on their own, the infection is still in your body unless it’s treated.

Several things make Syphilis easy to overlook:

• The sore is usually painless and heals by itself, typically within 3 to 8 weeks.
• Sores can be hidden inside the vagina or bottom, or in the mouth.
• The later rash, often on the palms of the hands and soles of the feet, can look like other skin conditions.
• Other later symptoms, such as a high temperature, headaches, tiredness and swollen glands, can feel like flu.
• Some signs, such as white patches in the mouth or patchy hair loss, aren’t ones most people link with an STI.

Read more in “What does a Syphilis sore look like?”

Without treatment, Syphilis moves through stages:

• Primary: a sore usually appears about 3 weeks after infection, although it can take between 9 and 90 days.
• Secondary: a rash and other symptoms can appear, typically around 3 months after infection, and clear up within 3 to 12 weeks.
• Latent: there are no symptoms. UK guidelines call the first 2 years after infection early latent, and the time after that late latent. About 1 in 4 people get secondary symptoms back during the early latent stage.
• Late: around a third of untreated people develop serious problems, usually 20 to 40 years after infection.

So Syphilis can go unnoticed for years, even decades. It can also affect the brain, eyes or ears at any stage, so get urgent medical care if you notice changes to your sight or hearing.

Yes. The NHS says that if you haven’t been treated, the infection is still in your body even when symptoms go away, so you can still pass it on.

Syphilis spreads through close contact with a sore, or with the warty growths that can appear later, during vaginal, anal or oral sex. It’s most likely to be passed on in the first 2 years after infection. UK guidelines say about a third of the sexual partners of someone with infectious Syphilis catch it. People with late latent Syphilis usually can’t pass it on through sex.

Syphilis can also pass to a baby during pregnancy, which can cause miscarriage, stillbirth or serious problems for the baby. That’s why the NHS offers a blood test for Syphilis in every pregnancy, ideally by 10 weeks.

The NHS says untreated Syphilis can cause serious and potentially life-threatening problems, including:

• heart problems, such as heart failure
• brain problems, such as fits, memory problems, personality changes and dementia
• nerve problems, such as shooting pains and pins and needles
• sight and hearing problems

The earlier Syphilis is treated, the better, which is why testing matters. Read more in “Silent infection: the importance of Syphilis testing”

A test is the only way to know if you have Syphilis. The main test is a blood test. If you have a sore, a swab from it can be tested too.

• Timing matters: a test in the first 3 months after sex can miss the infection, so UK guidelines recommend a repeat test 3 months after a risk.
• The main antibody tests usually stay positive for life, even after successful treatment. If you’ve had Syphilis before, tell whoever tests you, so your result can be read correctly.
• You can catch Syphilis again after treatment.

Syphilis is treated with antibiotics, usually a penicillin injection. The NHS advises avoiding sex until 2 weeks after you and your partner have finished treatment, and UK guidelines recommend follow-up blood tests at 3, 6 and 12 months.

Better2Know offers:

• Syphilis: a blood test for Syphilis antibodies from 9 days after sex, with results in 1 day. You can book it at one of our clinics or order a home test kit.
• Peace of Mind: tests for Syphilis, Chlamydia and Gonorrhoea from 14 days after sex, with results in 2 days. It’s also available as a home test kit.
• Blemish Screen: if you have a sore, blister or lump on or around your genitals, it tests a swab for Syphilis, Herpes 1, Herpes 2 and HPV, with results in 5 days.
• Full Screen: tests for 7 infections, including Syphilis and HIV, from 28 days after sex, with results in 3 days.

If you test before 45 days, a negative HIV result needs a repeat test. A Syphilis test in the first 3 months after sex can miss the infection, so you may need a repeat test. Not sure which test you need? Our Patient Care Team is available 24/7 on 020 7099 0955.

Can you have Syphilis for years without knowing?

Yes. After the early symptoms clear, Syphilis can stay in the body for years with no symptoms. Serious problems can appear decades later if it isn’t treated.

Can you catch Syphilis from kissing?

It’s possible if the person has a Syphilis sore in or around their mouth, because the infection spreads through contact with sores. It’s mainly passed on through sex.

My partner has Syphilis. Do I need a test?

Yes, even if you feel fine. Partners usually need testing and may be offered treatment straight away. A negative result in the first 3 months after sex can miss the infection, so you may need to test again.

You can have Syphilis and not know it. The first sore is often painless or hidden, later symptoms come and go, and the infection can then stay silent for years while it can still be passed on. A simple blood test can tell you, and Syphilis is treated with antibiotics.

Book a Syphilis test at a clinic near you or order a home test kit. Our Patient Care Team is available 24/7 on 020 7099 0955.

Not in the UK? Choose your country from the selector at the top of the page for local tests and prices.

This article originally appeared on 19 May 2023 and was last updated on 1 October 2026.

This article is general information and not a substitute for personal medical advice.

Sources

1. NHS, Syphilis, reviewed 17 March 2026. https://www.nhs.uk/conditions/syphilis/
2. British Association for Sexual Health and HIV, UK guidelines for the management of syphilis, 2024. https://www.bashh.org/_userfiles/pages/files/syphilis_2024.pdf
3. World Health Organization, Syphilis, 29 May 2025. https://www.who.int/news-room/fact-sheets/detail/syphilis
4. UK Health Security Agency, Sexually transmitted infections and screening for chlamydia in England: 2025 report, 2 June 2026. https://www.gov.uk/government/statistics/sexually-transmitted-infections-stis-annual-data-tables/sexually-transmitted-infections-and-screening-for-chlamydia-in-england-2025-report
5. NHS, Screening for hepatitis B, HIV and syphilis, reviewed 23 January 2024. https://www.nhs.uk/pregnancy/your-pregnancy-care/screening-for-hepatitis-b-hiv-and-syphilis/
6. NHS England, ISOSS Syphilis Report (for pregnancies between 1 April 2022 and 31 March 2023), 11 December 2025. https://www.gov.uk/government/publications/isoss-syphilis-report-for-pregnancies-between-1-april-2022-to-31-march-2023/isoss-syphilis-report-for-pregnancies-between-1-april-2022-and-31-march-2023
7. British HIV Association, British Association for Sexual Health and HIV and British Infection Association, Adult HIV testing guidelines, 2020. https://www.bashh.org/_userfiles/pages/files/resources/hivtesting2020wiley.pdf