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Chlamydia is one of the most common sexually transmitted infections (STIs) in the UK.
It’s passed on from one person to another through unprotected sex (sex without a condom). In 2010, there were 186,753 people who tested positive for chlamydia in England. Most of these - more than 150,000 - were people aged 24 or younger.
Most people who have chlamydia don’t notice any symptoms, and so don't know they have it. Research suggests that 50% of men and 70-80% of women don't get symptoms at all with chlamydia infection.
Symptoms of chlamydia could be pain when you urinate (pee), unusual discharge from the penis, vagina or rectum or, in women, bleeding between periods or after sex.
Find out more about chlamydia symptoms.
Getting tested for chlamydia
Testing for chlamydia is done with a urine test or a swab test. You don't always have to have a physical examination by a nurse or doctor.
Anyone can get a free confidential chlamydia test at a sexual health clinic, a GUM (genitourinary medicine) clinic or a GP surgery. Find out more about getting a chlamydia test.
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.
You can also buy chlamydia testing kits to do at home. The accuracy of these tests varies. If you use one of these tests, talk to your pharmacist or GP.
Chlamydia is easily treated with antibiotics. If chlamydia isn’t treated, the infection can sometimes spread to other parts of your body and lead to serious long-term health problems such as pelvic inflammatory disease and infertility (not being able to have children).
The National Chlamydia Screening Programme
Chlamydia is most common in people under 25 years old, although people of any age can get it. If you are under 25, you can get a free, confidential chlamydia test under the National Chlamydia Screening Programme (NCSP). This offers tests in various places, including some pharmacies. Find your nearest NCSP testing site.
Some NCSP areas may also send chlamydia testing kits to you through the post. You can request these online. Find out about free online chlamydia tests for under 25s.
Find out answers to some common questions about chlamydia: