Chlamydia: symptoms, testing, treatment and how long it takes to clear

The NHS says most people who have chlamydia do not have any symptoms. NICE CKS says infection is asymptomatic in at least 70% of women and 50% of men. If symptoms do appear, the NHS says they can start from 1 week to several months after infection.

The NHS says symptoms, if they develop, can begin from 1 week to several months after infection. Because many people never have symptoms, the only way to know is to test.

Once treatment begins, the NHS says it may be a single dose, or tablets for 7 to 14 days. NICE CKS gives first-line treatment as doxycycline twice a day for 7 days, and says to avoid sex until both you and your partner have completed the course. The NHS says to avoid vaginal, anal or oral sex until you and your partner have finished treatment and tests show you no longer have chlamydia, where retesting is advised.

Chlamydia is treated with antibiotics, according to the NHS. Sometimes you may start treatment before the test results come back, and you may need to be tested again after treatment to check you no longer have chlamydia. If you are pregnant, the NHS says you will be tested again 4 weeks after treatment.

NICE CKS says treatment should be started promptly in everyone who tests positive, ideally with referral to a sexual health (GUM) clinic for treatment, screening for other STIs and partner notification. A test of cure is not usually necessary, but is recommended in pregnancy, where poor compliance is suspected and where symptoms persist. It recommends repeat testing 3 to 6 months after treatment for people under 25 who are diagnosed, to check for re-infection.

In pregnancy or breastfeeding, doxycycline is not used, and CKS says other antibiotics may be considered after discussion with a specialist.

NICE CKS says genital chlamydia infection is the most common sexually transmitted bacterial infection in the UK. The NHS says it is spread through vaginal fluid and semen, and can pass from person to person by having vaginal, oral or anal sex without a condom. It can also be spread through vaginal fluid or semen that gets onto sex toys and your hands.

If you have chlamydia when you are pregnant, the NHS says it can pass to your baby during birth.

The NHS says a doctor or nurse will ask about your symptoms and sexual partners, and may need to check your penis or vagina. You may be asked for a pee sample, or a swab of fluid from your penis or vagina, which you may be able to do yourself. They may also swab your bottom, throat or eyes if these areas are affected. You can be tested even if you have no symptoms, and may be offered tests for other STIs at the same time.

If you do not have symptoms but want a test, you can use a self-test kit at home and send it to a lab. The NHS says you may be able to get a free kit from a sexual health clinic or some pharmacies, or buy one from some pharmacies, and that if you are under 25 you may be able to get free home test kits.

The UK Health Security Agency says that in community settings such as GPs and pharmacies, chlamydia screening is proactively offered to young women. It says everyone can still get tested if they need to, and sexual health services are unchanged, but men are not proactively offered a test unless there is an indication such as being a partner of someone with chlamydia or having symptoms.

The NHS says to go to a sexual health clinic or see a GP if you or a sexual partner think you might have chlamydia, if you or a sexual partner have had sex without a condom, or if you are pregnant or planning to get pregnant and think you might have chlamydia.

The NHS also advises getting tested once a year, or when you have a new sexual partner. NICE CKS notes the National Chlamydia Screening Programme recommends annual screening for all sexually active women younger than 25, or more frequently if they change partner.

If you have chlamydia, the NHS says your current and recent sexual partners need to be tested. A sexual health clinic can help you contact your partners, or they can contact them for you.

To avoid getting and spreading chlamydia, the NHS advises using condoms for vaginal or anal sex, using a condom or a latex or plastic square (dam) for oral sex, getting tested once a year or with a new partner, completing the full treatment, and not sharing sex toys (or washing them and covering them with a new condom before anyone else uses them).

The NHS says untreated chlamydia can lead to serious complications. The sooner you get treatment, the easier these complications are to treat.

• Infection of the womb, fallopian tubes and ovaries (pelvic inflammatory disease), which can lead to infertility or ectopic pregnancy.

• Infection in the testicles.

• Pain in the joints (reactive arthritis), which usually gets better after a few months.

The NHS says that if you are pregnant and have chlamydia that is not treated, it can be passed on to your baby during birth. This can cause an infection in your baby's eyes (conjunctivitis) or lungs (pneumonia), which can be treated with antibiotics.

If you are pregnant or planning to get pregnant and think you might have chlamydia, the NHS says to go to a sexual health clinic or see a GP. If you are treated in pregnancy, you will be tested again 4 weeks after treatment.

NHS sexual health clinics and GPs provide testing and treatment, and many sexual health clinics offer a walk-in service. Free or low-cost self-test kits are available from some clinics and pharmacies.

Private clinics and online services also offer testing and treatment. Whichever route you use, partner notification, completing the full course and any retesting are part of care, and a positive result should be followed by treatment and avoiding sex until you and your partner have completed it.