It's passed on through unprotected sex (sex without a condom) and is particularly common in sexually active teenagers and young adults.
If you're a woman, sexually active and under 25 in England, it's recommended that you have a chlamydia test once a year, and when you have sex with new or casual partners.
If you're a man, sexually active and under 25 in England, it's recommended that you have a chlamydia test once a year if you are not using condoms with new or casual partners.
Most people with chlamydia do not notice any symptoms and do not know they have it.
If you do develop symptoms, you may experience:
If you think you're at risk of having a sexually transmitted infection (STI) or have any symptoms of chlamydia, visit a GP, community contraceptive service or local genitourinary medicine (GUM) clinic to get tested.
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:
It can also be passed by a pregnant woman to her baby.
Chlamydia cannot be passed on through casual contact, such as kissing and hugging, or from sharing baths, towels, swimming pools, toilet seats or cutlery.
Although chlamydia does not 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, especially in women.
In women, untreated chlamydia can cause pelvic inflammatory disease (PID), ectopic pregnancy and infertility.
In men, in rare cases, chlamydia can spread to the testicles and epididymis (tubes that carry sperm from the testicles), causing them to become painful and swollen. This is known as epididymitis or epididymo-orchitis (inflammation of the testicles).
It can also sometimes cause reactive arthritis in men and women.
This is why it's important to get tested and treated as soon as possible if you think you might have chlamydia.
Testing for chlamydia is done with a urine test or a swab test.
You do not 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.
In England, if you're a woman under 25 years old, you may be offered a chlamydia test when you visit some health services, for example a pharmacy or GP. This offer is part of the National Chlamydia Screening Programme (NCSP).
If you're offered a chlamydia test you should consider taking it.
If you're a woman, sexually active and under 25 in England, it's recommended that you have a chlamydia test once a year, and when you have sex with new or casual partners.
If you're a man, sexually active and under 25 in England, it's recommended that you have a chlamydia test once a year if you are not using condoms with new or casual partners.
You can also buy chlamydia testing kits to do at home.
Chlamydia can usually be treated easily with antibiotics.
You may be given a course of doxycycline to take for a week or azithromycin to take once a day for 3 days.
If you have doxycycline, you should not have sex (including oral sex) until you and your current sexual partner have finished treatment.
If you have azithromycin, you should wait 7 days after treatment before having sex (including oral sex).
It's important that your current sexual partner and any other recent sexual partners you have had are also tested and treated to help stop the spread of the infection.
Under-25s who have chlamydia should 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.
Sexual health or genitourinary medicine (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 will not have your name on it, so your confidentiality will be protected.
Anyone who's sexually active can catch chlamydia.
You're most at risk if you have a new sexual partner or do not use a barrier method of contraception, such as a condom, when having sex.
You can help to prevent the spread of chlamydia by:
If you do share sex toys, wash them or cover them with a new condom between each person who uses them.
Page last reviewed: 01 September 2021
Next review due: 01 September 2024