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

About Chlamydia

Chlamydia is passed on through unprotected sex (sex without a condom)

If you are under 25 and sexually active it’s recommended you are tested for chlamydia once a year, and when you have sex with new or casual partners.

Signs and Symptoms

Most people with chlamydia do not notice any symptoms and do not know they have it.

If you do have symptoms you may experience:

  • Pain when peeing
  • Unusual discharge from the vagina, penis or bottom
  • In women, stomach pain, bleeding after sex or bleeding between periods
  • In men, pain and swelling in the testicles

How is it Transmitted?

Chlamydia is spread through sex or contact with infected genital fluids (semen or vaginal fluid).

You can get chlamydia several ways:

  • Unprotected vaginal, anal or oral sex
  • Sharing unwashed sex toys
  • Your genitals coming into contact with your partner’s genitals (even if there’s no penetration or ejaculation)
  • Infected semen or vaginal fluid getting into your eye

How to Get Tested

Self Test

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You can help prevent the spread of chlamydia by:

  • Using a condom every time you have vaginal or anal sex
  • Using a condom to cover the penis during oral sex
  • Using a dam (a piece of thin, soft plastic or latex) to cover the female genitals during oral sex or when rubbing female genitals together
  • Avoiding sharing sex toys


Chlamydia can be easily treated with antibiotics. Your doctor can prescribe the right antibiotic for you.

Your current sexual partner and any other recent sexual partners should also be tested and treated to stop the spread of infection.

Under-25’s who have chlamydia will be offered another test 3 to 6 months after being treated. This is because young adults who test positive for chlamydia are at increased risk of catching it again.


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Contacting a sexual health service for the first time can be a little daunting, so here are some easy answers to many of the questions you may have.

Is chlamydia serious?

Chlamydia is typically a minor illness but if not treated early it can be serious. If left untreated, the infection can spread to other parts of the body leading to long-term health problems including pelvic inflammatory disease in women.

How soon do symptoms appear?

Symptoms usually appear after 1 to 3 weeks of infection but can start much later. However, about 50% of men and 70% of women who are infected do not have any symptoms.

What should I do if I think I have chlamydia?

If you think you have an STI go to your GP or local sexual health clinic.

How do I get tested?

You can test yourself for chlamydia at home.  To order a test click here. For information on how to take a test visit our resource hub.

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