What you need to know about syphilis

Syphilis is a sexually transmitted infection (STI) that is most easily passed on by contact with a syphilis sore during sex. Early on, it can cause sores on or in the genitals, anus or mouth. The infection can be cured with a single dose of penicillin, and there are ways to lower the chance of getting or passing on syphilis, such as using a condom each time you have sex.

The words we use here – CATIE is committed to using language that is relevant to everyone. People use different terms to describe their bodies. This text uses medical terms, such as vagina and penis, to describe genitals. Other people may use other terms, such as private parts or dick or front hole. CATIE acknowledges and respects that people use words that they are most comfortable with.

What is syphilis?

Syphilis is a sexually transmitted infection (STI). It can cause sores on or in the genitals, anus, rectum, and/or lips and mouth and can lead to other health complications. A person with syphilis can pass it on to another person during sex.

Many people with syphilis have no symptoms, so they don’t know they have syphilis. When symptoms of initial infection do occur, they usually take two to three weeks to appear. Untreated syphilis progresses through stages. Common symptoms vary depending on the stage.

Primary syphilis: A painless sore appears at the site of infection but will heal in three to six weeks with or without treatment. Because many people do not see the sore, they are not aware of the infection.

Secondary syphilis: A non-itchy rash may appear, most commonly on the chest, stomach, genitals, palms of the hands and soles of the feet, two weeks to three months after infection, and it may last for two to six weeks. Additional sores may also appear. Fever, headache, muscle ache, lack of appetite and fatigue can occur.

Late syphilis (tertiary stage): Without treatment, secondary syphilis turns into late syphilis (also called latent or tertiary syphilis). This can develop from two to 30 years after infection. Initially, the infection may show no signs but the syphilis germs are injuring tissues. Eventually, the injury to important organs, such as the eyes, skin, bones, liver, kidneys and heart, can cause symptoms.

Neurosyphilis: Syphilis can affect the brain. This is called neurosyphilis. In cases where the brain is affected, changes in personality can occur, as can problems with thinking clearly and memory. Neurosyphilis can occur at any stage of syphilis.

Could I get syphilis?

All people who are sexually active, and people who share drug injection equipment, can get syphilis.

Syphilis can be passed on by:

  • anal, oral or vaginal sex
  • a pregnant parent to their child during pregnancy or childbirth
  • sharing equipment for injecting drugs
  • sharing sex toys
  • deep wet kissing

Syphilis and HIV

Having syphilis increases the chance of getting HIV. People whose HIV is not well treated may be at increased risk for passing on HIV if they also have syphilis. People with HIV may also experience complications earlier and more severely than people without HIV. 

What can I do?

Prevent infection

Using a condom during anal or vaginal intercourse may help to lower the chance of getting or passing on syphilis.

Using a condom or oral dam during oral sex may help to lower the chance of getting or passing on syphilis.

There is no vaccine to protect against syphilis.

Get tested

The only way to know for sure whether or not you have syphilis is to get tested. A doctor or nurse can do the test. If the infection is in the primary or secondary stages, tests can involve blood tests or testing fluids taken from a sore.

It is a good idea to get tested for other sexually transmitted infections (STIs), including HIV, when you get tested for syphilis. Other STIs can be passed on in the same way as syphilis. Talk to your healthcare provider about how often you should be tested for syphilis and other STIs.

If you are diagnosed with syphilis, a public health staff person will talk to you about informing your sex partners that they might have been exposed to syphilis and encouraging them to get tested. Your identity will not be revealed.

Get treated

Syphilis can be cured with a single dose of penicillin if diagnosed within the first year of infection.

But you can be infected again. Being treated for syphilis does not protect you from getting syphilis in the future.


This information sheet was developed in partnership with the Sex Information and Education Council of Canada (SIECCAN).


Syphilis CATIE fact sheet