Chlamydia is caused by bacteria which are found in infected semen and vaginal fluids.

Chlamydia symptoms


Symptoms might show within one to three weeks of infection, but around half of men and most women have no symptoms.

Chlamydia in the penis can cause:

  • a whitish, cloudy or watery discharge 
  • pain when urinating
  • burning or itching in the urethra (the tube that carries urine out of the body)
  • pain and swelling in the testicles.

In the vagina, it can cause:

  • a change in vaginal discharge
  • pain when urinating
  • pain in the belly or lower back
  • pain during sex
  • bleeding between periods or after sex.

In the rectum it generally causes no symptoms but might cause discomfort and discharge.

Chlamydia in the throat is usually symptom free.

In the eyes, it can cause pain, redness and discharge (conjunctivitis).

How it's passed on


You can get chlamydia through:

  • vaginal, oral or anal sex without condoms
  • sharing sex toys that are not washed or covered with a condom each time they are used on a different person
  • your genitals (penis or vagina) coming into contact with your partner’s genitals
  • infected semen or vaginal fluid getting in your eye.

It's not yet known whether chlamydia is spread on fingers when you touch an infected part of the body, then touch other parts of your body or someone else’s.

Using the external or internal condom cuts the risk. Other types of contraception, such as the contraceptive pill, offer no protection against STIs.

If you are living with HIV, having untreated chlamydia could make it more likely that you’ll pass on HIV during unprotected sex. But if HIV drugs have made your viral load undetectable then chlamydia or other infections don’t appear to make you more likely to pass on HIV.

Chlamydia tests and treatment


Chlamydia tests are simple and painless.

A sample of cells can be collected for testing in two ways:

  • giving a sample of urine
  • gently wiping a swab (small cotton bud) over the area that might be infected.

Swabs only take a few seconds and don’t hurt – they may be uncomfortable for a moment or two.

Chlamydia is treated with antibiotics. The most common treatments are:

You could pass on the infection if you have sex before treatment has finished. This includes vaginal, anal and oral sex, even with a condom. To prevent re-infection or passing the infection on, wait 7 days after your treatment has finished to have sex.

Even if you are given a single dose of antibiotics, you need to wait 7 days to have sex.

It is important that people you have had sex with recently are also tested and treated. A clinic can contact them if you don’t want to.

Untreated chlamydia


If chlamydia is not treated it can sometimes causes serious problems, including pain, inflammation and infertility in men and women. It can also lead to complications in pregnancy.

Regular testing


The more people you have sex with, especially unprotected sex, the more chance there is of catching infections like chlamydia. You can have them without knowing, so regular check-ups are a good idea, especially if you are starting a new relationship and/or you want to stop using condoms with your partner.

Most people get tested and treated for infections like chlamydia at sexual health or GUM (genitourinary medicine) clinics. It's free and confidential, so no one else, including your GP, will be told about your visit. Some GP surgeries also test for and treat these infections.

You can also get chlamydia testing kits to do at home.