Chlamydia is one of the most common sexually transmitted infections (STIs) in the UK.

It's passed on through unprotected sex (sex without a condom) and is particularly common in sexually active teenagers and young adults.

If you live in England, are under 25 and are sexually active, it's recommended that you get tested for chlamydia every year or when you change sexual partner.

Symptoms of chlamydia

Most people with chlamydia don't notice any symptoms and don't know they have it.

If you do develop symptoms, you may experience:

  • pain when peeing
  • unusual discharge from the vagina, penis or rectum (back passage)
  • in women, pain in the tummy, bleeding after sex and bleeding between periods
  • in men, pain and swelling in the testicles

If you think you're at risk of having an STI or have any symptoms of chlamydia, visit your GP, community contraceptive service or local genitourinary medicine (GUM) clinic to get tested.

Read more about chlamydia symptoms.

How do you get chlamydia?

Chlamydia is a bacterial infection. The bacteria are usually spread through sex or contact with infected genital fluids (semen or vaginal fluid).

You can get chlamydia through:

  • unprotected vaginal, anal or oral sex
  • sharing sex toys that aren't washed or covered with a new condom each time they're used
  • your genitals coming into contact with your partner's genitals – this means you can get chlamydia from someone even if there is no penetration, orgasm or ejaculation
  • infected semen or vaginal fluid getting into your eye

It can also be passed by a pregnant woman to her baby – read about the complications of chlamydia for more information about this.

Chlamydia can't be passed on through casual contact, such as kissing and hugging, or from sharing baths, towels, swimming pools, toilet seats or cutlery.

Is chlamydia serious?

Although chlamydia doesn't usually cause any symptoms and can normally be treated with a short course of antibiotics, it can be serious if it's not treated early on.

If left untreated, the infection can spread to other parts of your body and lead to long-term health problems, such as pelvic inflammatory disease (PID), epididymo-orchitis (inflammation of the testicles) and infertility. It can also sometimes cause reactive arthritis.

This is why it's important to get tested and treated as soon as possible if you think you might have chlamydia.

Read more about the complications of chlamydia.

Getting tested for chlamydia

Testing for chlamydia is done with a urine test or a swab test. You don't always need a physical examination by a nurse or doctor.

Anyone can get a free and confidential chlamydia test at a sexual health clinic, a genitourinary medicine (GUM) clinic or a GP surgery.

People under 25 years old can also get tested by the National Chlamydia Screening Programme (NCSP). This is often in places such as pharmacies, contraception clinics or colleges. If you live in England, you're under 25 and you're sexually active, you should get tested for chlamydia every year or when you change sexual partner, as you're more likely to catch it.

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

Read more about getting a chlamydia test.

How chlamydia is treated

Chlamydia can usually be treated easily with antibiotics. You may be given some tablets to take all on 1 day, or a longer course of capsules to take for a week.

You shouldn't have sex until you and your current sexual partner have finished treatment. If you had the 1-day course of treatment, you should avoid having sex for a week afterwards.

It's important that your current sexual partner and any other recent sexual partners you've had are also tested and treated to help stop the spread of the infection.

The NCSP recommends that under-25s who have chlamydia should be offered another test around 3 months after being treated. This is because young adults who test positive for chlamydia are at increased risk of catching it again.

Sexual health or GUM clinics can help you contact your sexual partners. Either you or the clinic can speak to them, or they can be sent a note advising them to get tested. The note won't have your name on it, so your confidentiality will be protected.

Read more about treating chlamydia.

Preventing chlamydia

Anyone who is sexually active can catch chlamydia. You're most at risk if you have a new sexual partner or don't use a barrier method of contraception, such as a condom, when having sex.

You can help to 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
  • not sharing sex toys

If you do share sex toys, wash them or cover them with a new condom between each person who uses them.

Common questions

Find answers to some common questions about chlamydia: