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Dr Karen Martin
Reviewed by Dr Karen MartinReviewed on 19.10.2023 | 3 minutes read

Chlamydia is a very common sexually transmitted infection (STI). It is a bacterium that can spread in semen or vaginal fluid and infect the vagina, uterus (womb), urethra (tube for the passage of urine, plus semen in men), the penis, rectum and, less commonly, the throat and eyes.

It may cause no symptoms at all but if it does, signs to look out for are a vaginal, penile or rectal discharge. This is usually watery and white or cloudy, and there may also be pain or stinging when peeing. In the longer term, men may get pain in the testicles and women develop pain in the pelvis, especially when having sex, and bleeding after sex or between periods. Ultimately it can cause infertility if left untreated. It may also cause joint inflammation (reactive arthritis) and irritated red eyes (conjunctivitis).

Given the high stakes and the fact that you may have no symptoms at all, it’s important to get tested regularly. This is especially important if you are aged 16 to 25, as this is the highest risk age group. If you're a woman, sexually active and under 25, 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 it's recommended that you have a chlamydia test once a year if you’re not using condoms with new or casual partners. Get an STI test at the change of any partner (use condoms until you both get the all-clear) and if you’re changing partners regularly or have multiple partners, get tested every three months.

Doctor’s advice

Next steps

Chlamydia is highly contagious, and you should get tested and treated. You can catch chlamydia via vaginal, anal and oral sex, and by sharing sex toys. Condoms will protect you.

A positive test can sometimes be a surprise, but it’s not always easy to say when and from whom you contracted chlamydia if you’ve had more than one partner – you may have no symptoms or they may take weeks or months to emerge.

When should I see my doctor?

You should see your doctor or sexual health clinic urgently if you have symptoms, or if you have been informed a partner has chlamydia, in which case you will be treated regardless of the test outcome.

At the clinic, women will be asked to take a vaginal swab from themselves – this is quick and painless – and men will be asked to pee in a jar at least an hour after they last passed urine. This test checks for chlamydia and gonorrhea (another common STI) at the same time.

It can take up to two weeks for chlamydia to show up on a test after unprotected sex, but you can get a test right away and, if negative, follow it up two weeks later. If you have no symptoms, wait two weeks after unprotected sex before getting tested.

If you’re pregnant, it’s especially important to get tested and treated, as this can pass to your baby during birth and infect their eyes, causing conjunctivitis, or lungs, causing pneumonia. This is usually part of the routine screening in the first round of blood tests after birth. Tell any sexual health clinic you are pregnant, as they will consider antibiotics that are safe in pregnancy.

Any other symptoms or risk factors will be considered at the clinic, and other tests may be offered, including HIV, syphilis and possibly Hepatitis B.

And what about treatment?

Treatment is quick and simple: a short course of antibiotic tablets, usually doxycycline or azithromycin. 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). You don’t normally need a second test to check if the infection has cleared, as antibiotics are a reliable treatment.

It’s really important to tell any sexual partners within the previous three months of your positive test – the clinic may be able to help send anonymous messages if that makes it feel less awkward.

Discharge or pain when you pee should clear up within days of treatment, testicular or pelvic pain may take a couple of weeks, and vaginal bleeding may take until the next cycle to improve. If you still have symptoms, return to the sexual health clinic or see your doctor to consider other causes.

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This article has been written by UK-based doctors and pharmacists, so some advice may not apply to US users and some suggested treatments may not be available. For more information, please see our T&Cs.
Dr Karen Martin
Reviewed by Dr Karen Martin
Reviewed on 19.10.2023
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