Syphilis: stages, symptoms, testing and treatment

Syphilis is a sexually transmitted infection (STI) caused by a bacterium. It is cured with antibiotics, usually a penicillin injection. The sooner it is treated the better: treatment stops the infection, but it cannot always repair damage already done.

It has been rising again in many countries. The World Health Organization (WHO) estimates that 8 million adults aged 15 to 49 acquired syphilis worldwide in 2022. In Europe, the European Centre for Disease Prevention and Control (ECDC) recorded 45,577 cases in 2024, more than double the 2015 level, and congenital syphilis cases nearly doubled between 2023 and 2024.

What it is

It is caused by the bacterium Treponema pallidum. It develops in stages, with spells of symptoms and spells with none. That is why it can go unnoticed for a long time. Having had it once does not protect you: you can catch it again.

Symptoms and stages

• Primary syphilis: around three weeks after contact, sometimes longer, a sore or ulcer called a chancre appears. It is usually firm and painless, and there may be one or several. It appears where the bacterium entered: the genitals, anus, rectum, lips or mouth. It lasts 3 to 6 weeks and heals on its own, but the infection carries on.
• Secondary syphilis: weeks later, a rash that does not itch may appear, often on the palms of the hands and soles of the feet. There may also be a fever, swollen glands, a sore throat, tiredness, white patches in the mouth or patchy hair loss. These symptoms also clear up without treatment.
• Latent stage: there are no symptoms, sometimes for years, but the infection is still in the body.
• Tertiary syphilis: this is uncommon. It can appear 10 to 30 years later and damage the heart, blood vessels, brain and other organs. It can be fatal.

Syphilis can also affect the nervous system, eyes or ears at any stage (neurosyphilis, ocular syphilis and otosyphilis).

How it spreads – and how it doesn't

It spreads through direct contact with a syphilis sore or lesion during vaginal, anal or oral sex. It is most infectious in the early stages, roughly the first two years. During pregnancy it can pass to the baby through the placenta. It can also spread through sharing needles.

It does not spread through toilet seats, door handles, swimming pools, hot tubs, clothing or shared cutlery.

Testing: when and how

The usual test is a blood test. If you have a sore, a swab may also be taken from it. Rapid tests can give a result in minutes.

The blood test can take up to 12 weeks to turn positive after infection. If you test earlier, you may be asked to test again after that time. If you have a sore or a rash, do not wait: get checked now.

People at higher risk, such as those with new or several partners, should test at least once a year. See how often to get tested for STIs. Because syphilis raises the risk of getting HIV, you will usually be offered an HIV test too.

Treatment: it can be cured

Syphilis is cured with antibiotics. The treatment of choice is a penicillin injection. In the early stages one injection is usually enough. Later stages need several, spread over a few weeks. If you are allergic to penicillin, other antibiotics are available.

• Reaction to treatment: in the first 24 hours some people get a fever or flu-like symptoms. This usually settles by itself.
• Follow-up: you will have several blood tests over the following year to check the treatment has worked.
• When to have sex again: the NHS advises waiting two weeks after both you and your partner have finished treatment.
• Partners: current and recent partners need testing and treatment.

Complications if it isn't treated

Without treatment, over the years syphilis can cause serious problems: damage to the heart and aorta, memory loss, personality changes, seizures, dementia, loss of sight or hearing, and damage to bones, joints and other organs. According to WHO, syphilis also roughly doubles the risk of getting HIV.

Syphilis and pregnancy

Syphilis can pass to the baby during pregnancy (congenital syphilis). According to WHO, if it is not treated, or treated late, it causes serious problems in 50–80% of pregnancies: miscarriage, stillbirth, death of the newborn, premature birth or low birth weight. That is why it is tested for at the first antenatal appointment and treated straight away if positive. Penicillin is the only treatment WHO recommends in pregnancy, because it is the one that prevents passing it to the baby. Read more in our pregnancy and postnatal guide.

Prevention

• Use a condom for vaginal and anal sex, and a condom or dental dam for oral sex. It greatly lowers the risk but does not cover every area where sores can be. Check the common condom mistakes.
• Get tested regularly if you have new partners.
• If you are diagnosed, tell your partners so they can be treated too.
• Do not share needles, or sex toys unless they are washed and covered with a new condom.

There is no vaccine against syphilis.

When to get help

Book an appointment with your GP or a sexual health clinic if you notice a sore, even a painless one, or a rash on your palms or soles; if a partner tells you they have syphilis; if you have had sex without a condom with a new partner; or if you are pregnant. Get urgent help if you have changes in your vision, hearing loss, ringing in the ears or a severe headache. Your visit is confidential and free of judgement.