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Chlamydia trachomatis is a bacteria that is passed from one person to another through sex. It can cause problems if it's left untreated and so getting a test after unprotected sex is important.

What is it?

Chlamydia (caused by chlamydia trachomatis) is the most common bacterial sexually transmitted infection (STI) in the UK. It is easily treated and if found and treated early will not cause any problems.

However, if it is left untreated it can cause problems. In women these could be low abdominal pain due to pelvic inflammatory disease (PID – see section below), infertility (difficulty becoming pregnant) and ectopic pregnancy (pregnancy in fallopian tube). In men it can cause painful, swollen testicles (see section on epididymo-orchitis below).

How do I catch it?

Chlamydia trachomatis is a bacteria that is passed from one person to another through sex.

The bacteria infect the cells lining the cervix (neck of the womb), urethra (tube where urine comes out), rectum (back passage) and sometimes the eyes or throat.

It is spread through vaginal, oral and anal sex. You can also catch it from sex toys if they are not washed or covered by a new condom each time they are used. Occasionally it can be passed on fingers to eyes causing an eye infection, or from a mother to her baby at birth causing an eye or lung infection.

You can’t catch it from kissing, hugging, sharing towels, swimming pools, toilets or sharing cups, plates or cutlery.

What symptoms could I have?

50% of men will not have any obvious symptoms. In men with symptoms, the most common problems are discharge (liquid) from the end of the penis and pain or tingling when passing urine.

70 – 80% of women will not have any obvious symptoms. In women with symptoms, there might be an increase or change in vaginal discharge, pain passing urine, lower abdominal (tummy) pain, pain during sex or bleeding in between periods.

How do you test for it?

Chlamydia tests can be done on a urine sample in men or swabs taken from the genitals (penis, vagina and bum) and throat. We will recommend the best test for you depending on whether you have any symptoms, what they are and based on the type of sex you have had.

You can find out more about self-testing and order a postal kit here or you can use the service finder to find Chlamydia testing near you.

How do you treat it?

Chlamydia is treated with antibiotics; most often a one-off dose which we will give you in the clinic.

If you are treated for chlamydia, it is essential that your partner is also treated before you have sex again.

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