Syphilis is a sexually transmitted infection caused by the bacteria Treponema pallidum.


You can catch syphilis through oral, vaginal or anal sex with a person who has syphilis. It is transmitted through skin-to-skin contact with an infected area. The chance of catching syphilis is greatly reduced by using condoms during sex. Condoms also protect you against other sexually transmissible infections. Syphilis is highly contagious when a sore or rash is present. More rarely, syphilis is transmitted from mother to baby during pregnancy.


Not all people with syphilis have symptoms so you may not know you have it unless you have a blood test for it. There are 3 stages of infection known as primary, secondary and latent syphilis. The symptoms vary according to the stage. People with primary or secondary syphilis are infectious to their sexual partners.


A hard, painless sore occurs usually on the genitals but it may be at other sites of sexual contact such as the mouth or anus. Because it is typically painless and may occur in hidden sites (eg cervix or mouth) you may not notice it. The sore or ulcer usually appears 3-4 weeks after infection. However, it can occur 10 to 90 days after infection which may make it difficult to know when you caught syphilis. The sore usually heals by itself within about 4 weeks. Even though the sore heals, if you have not had treatment, you still have syphilis and can pass it on to others.


Symptoms may occur 2-4 months after infection and last several weeks. There may be a flat red skin rash on the back, chest, hands and feet. Other symptoms include fever, swelling of the glands in the groin and armpits, a genital rash, hair loss and general tiredness. If untreated, these symptoms may come and go for up to 2 years. While the rash is present, secondary syphilis is highly infectious.


If syphilis is not treated in the primary or secondary phase it becomes latent. At this stage there are no symptoms and it is only picked up on blood tests. If syphilis is diagnosed and treated early in the latent phase there are usually no problems. About a third of people who have untreated latent syphilis develop tertiary syphilis. This can cause serious problems, mainly in the brain and heart. If you have latent syphilis you may need further tests, specialist review and longer treatment. Latent syphilis is not infectious and can be avoided by early treatment.


Your doctor may suggest the diagnosis of syphilis based on the appearance of a genital sore or body rash.
They may do a swab test from the sore to look under the microscope or to look for syphilis DNA (genetic material). They will also order blood tests. The blood tests measure antibodies, your body’s response to infection. It can take 3 months to develop antibodies, so the tests may be negative early on.

One part of the blood test looks for past infection and one part looks for current infection. The blood tests are also used to monitor your body’s response to the treatment and may help work out how long you have had syphilis.


Syphilis is treated with penicillin. If you are allergic to penicillin there are alternative treatments.

Although the treatment is straightforward, it is important to have repeat blood tests to check that the treatment has worked. Follow-up blood tests may be recommended at 3, 6 and 12 months after treatment

After treatment with penicillin some people (particularly those who have early syphilis) have a flu-like illness for 24 hours. This includes fevers, aches and pains and generally feeling unwell. It will go away and doesn’t require any specific treatment except plenty of rest and fluids.


If you have been diagnosed with syphilis, all of your sexual partners from the last few months should be checked by a doctor. If you had sex with them while the rash or sore was present they will usually need treatment too.

It is very important all (both regular and casual) sex partners are checked because if syphilis is not treated it can cause serious problems later on. If you have difficulty telling your partners, we have a website you can visit As well as general advice and sample conversations it has emails, SMSs and letters you can send to your partners either personally or anonymously.

You should not have sex until your rash or sore clears up and wait at least a week after treatment.

This fact sheet is designed to provide you with information on Syphilis. It is not intended to replace the need for a consultation with your doctor. All clients are strongly advised to check with their doctor about any specific questions or concerns they may have. Every effort has been taken to ensure that the information in this pamphlet is correct at the time of printing.
Last Updated December 2017