• Help & Advice
  • Find a Service
    Close icon


Find out about the symptoms, causes and treatment of chlamydia.

Chlamydia is a bacterial infection. It is the most common sexually transmitted infection (STI) in the UK and is most common in under 25s.

Signs and symptoms of chlamydia

Chlamydia is sometimes described as a ‘silent’ infection due to the fact about 75% of women and 50% of men with chlamydia don’t have any obvious signs or symptoms.

If you do have symptoms, they can often take a few weeks to appear and you might notice:

  • Unusual discharge from the vagina, penis or rectum
  • Pain when peeing
  • Bleeding during or after sex
  • Pelvic and lower abdominal pain
  • Heavy periods or bleeding between periods
  • Abdominal pain in women during vaginal sex
  • Painful swelling of testicles
  • Burning and itching in the genital area (men)

Chlamydia can also infect the rectum or throat if you have unprotected anal or oral sex. If infected semen or vaginal fluid comes into contact with your eyes, this can cause conjunctivitis.


If left untreated, chlamydia can cause infertility. Women are at risk of developing pelvic inflammatory disease (PID) and suffering damage to the fallopian tubes, and men can get an infection in their testicles.

The causes and spread of chlamydia

Chlamydia is caused by bacteria called chlamydia trachomatis that is found in semen and vaginal fluid of people who have the infection. It is passed from one person to another through:

  • Unprotected vaginal sex
  • Unprotected anal sex
  • Unprotected oral sex
  • Your genitals coming into contact with your partners genitals
  • Sharing sex toys without washing them or covering them with a condom with each use

It is not clear if chlamydia can be passed on by transferring fluids on the fingers.

You cannot get chlamydia from kissing, hugging, sharing baths or towels, swimming pools, toilet seats or from sharing cups, plates or cutlery.

Chlamydia can also be passed from mother to baby during birth but can be treated during pregnancy with antibiotics

Testing for chlamydia

If you’ve had unprotected sex, don’t wait and hope for the best, have a test as soon as you can. Accurate results should appear after two weeks.


Testing for chlamydia is really simple, painless and doesn’t necessarily require a physical examination by a nurse or doctor.

The test is done with either a urine test or a swab test.

Swab test:

  • The swab (looks like a small cotton bud) collects a sample from inside the vagina or from the tip of the penis.
  • Very often you can take the swab from inside the vagina yourself.
  • A doctor or nurse may take the swab from the tip of the penis or if you have had oral or anal sex then a swab may be taken from either your throat or rectum.
  • Taking the swab may be slightly uncomfortable but should not be painful.

You may be advised to have another test two weeks after having sex. Cervical smear tests and routine blood tests will not detect chlamydia.

You may be given treatment if you have symptoms which suggest that you could potentially have chlamydia, even if the results of your test have not come back yet. You will always be offered treatment if your partner is found to have chlamydia.

Chlamydia testing is free and you can get one at Brook services, other young people’s services, GUM or sexual health clinics or at some GP surgeries. Find your nearest using our find a service tool.

If you have a vagina and are under 25 you may be offered a Chlamydia test for free as part of the National Chlamydia Screening Programme in a range of setting from pharmacies to colleges. This is a programme to help screen those without symptoms.

It is also possible to buy chlamydia self-tests.

Treatment of chlamydia

Chlamydia is treated with a course of antibiotics. The two most commonly prescribed treatments are:

Most antibiotics are safe to use with hormonal contraception (like the pill, patch, injection or implant) but talk to the person prescribing the treatment to make sure. Tell the nurse or doctor if you are pregnant or think you may be, or if you are breastfeeding. This will affect the type of antibiotic you are given.

Side effects are usually very mild but may include stomach ache, diarrhoea, feeling sick and thrush.

If you had symptoms, you should notice improvements quite quickly. You should go back to where you had your test if:

  • The symptoms don’t improve within a week
  • You have unprotected sex again
  • You had unprotected sex with your partner before the treatment was finished
  • You did not follow the instructions or complete the treatment
  • The test was negative, but you develop signs and symptoms of chlamydia

You shouldn’t have sex for seven days after your treatment, to prevent you being re-infected or passing the infection on.


It is important that you tell any sexual partners from the last six months that you are being treated for chlamydia, so that they go for treatment too.
More about talking to people about STIs

Some clinics may also offer to contact your partner using partner notification. This will warn them they may have been exposed to an STI and to recommend they get tested, but it doesn’t mention your name.

  • On this page

    Other Stuff you might find useful…


    Do I have an STI?




    How do I use a condom?


    Talking about condoms with your partner

    Our friendly staff are here to help
    Find a Service near you

    100% free & confidential