Chlamydia is caused by bacteria (tiny germs) called Chlamydia trachomatis.

In people with chlamydia, the bacteria are most commonly found in the cervix (entrance to the uterus) and urethra (the tube you pee from). The bacteria can also infect the throat, the rectum (back passage), and the eyes.

Sometimes chlamydia can spread to other parts of the reproductive system, including the uterus (womb), fallopian tubes, ovaries, and testicles.

Anyone who’s sexually active can get and pass on chlamydia. You don’t need to have lots of sexual partners.

It’s usually passed on through sex or sexual contact.

Chlamydia is usually passed on through vaginal, anal or oral sex without a condom with someone with the infection, or by coming into contact with the semen (cum or pre- cum) or vaginal fluids of someone who has it.

Chlamydia:

• is most commonly spread through vaginal/ frontal or anal sex without a condom
  can be spread by sharing sex toys that aren’t washed or covered with a new condom each time they’re used
• can be spread by giving or receiving oral sex (going down, giving head) with someone who has the infection; the advice is to use a condom or a dam (a latex or plastic square that covers the anus or vulva)
• may sometimes be transferred from the genitals to the eye(s) by the fingers and cause conjunctivitis (infection or irritation of the eye); this isn’t common
• may sometimes spread to the rectum from vaginal discharge; you don’t need to have anal sex for this to happen.

If you’re pregnant it’s possible to pass chlamydia to the baby – also see below for What if I’m pregnant?
It’s not clear if chlamydia can be spread by transferring infected semen or vaginal fluid to another person’s genitals on the fingers or through rubbing vulvas (female genitals) together.

You cannot get chlamydia from hugging, sharing baths or towels, swimming pools, toilet seats or sharing cups, plates or cutlery.

Most people with chlamydia won’t have any obvious signs or symptoms or will have symptoms so mild they’re not noticed.

If you do get signs and symptoms, they can show up soon after coming into contact with chlamydia, many months later, or not until the infection spreads to other parts of your body. They most usually show up after 1 to 3 weeks.

If you have a vagina/front hole you may notice:

• Bleeding between periods and/or heavier periods or withdrawal bleeds
• Bleeding after sex
• Pain when you have sex
• Pelvic pain (pain low down in the tummy)
• Unusual or increased vaginal discharge
• Pain when passing urine (peeing)

If you have a penis you may notice:

• An unusual discharge from the tip of the penis. It may be white/cloudy or watery
• Pain or a burning feeling when passing urine (peeing)
• Pain in the testicles (balls)

With other parts of the body:

• Infection in the rectum (back passage) doesn’t usually have any signs or symptoms but may cause discomfort, pain or discharge
• Infection in the throat is less common than genital infection and usually has no symptoms
• Infection in the eyes can cause pain, swelling, irritation and/or discharge

Anyone sexually active can get chlamydia. You can only be certain you have it if you have a test.

It’s important not to delay testing so that you can start treatment and don’t pass chlamydia on to anyone else.

Consider doing a test if:

• you or a sexual partner have, or think you might have, symptoms
• you’ve recently had sex without a condom with a new partner
• you or a partner have had sex without a condom with other partners
• during a vaginal examination, your doctor or nurse says that the cervix is inflamed and/or there’s an unusual discharge
• a sexual partner tells you they have an STI
• you have another STI

You could have chlamydia even if a partner’s test is negative. The only way to make sure you don’t have chlamydia is to get tested yourself.

If you have one STI, you’ll be encouraged to test for others as you can have more than one STI at the same time.

If you’ve had chlamydia once, you won’t be immune – you can get it again.

Chlamydia tests for people under 25

You’re more likely to have chlamydia if you’re under 25, have a new sexual partner, or more than 1 sexual partner in the last year, and if you haven’t used condoms.

In England, if you’re aged under 25 it’s recommended that:

• sexually active women and other people with a womb or ovaries have a chlamydia test when you change sexual partner, and once a year
• sexually active men have a chlamydia test once a year if not using condoms with new or casual partners

It’s important not to delay getting a test if you think you may have chlamydia. The earlier chlamydia is treated, the less likely you are to have any complications.

A chlamydia test can be done straight away but you may be advised to have another test 2 weeks after having sex.

You can have a test even if you don’t have any symptoms.

If you have a vagina/front hole:

• A test is usually done by gently wiping a swab around the inside of your vagina to collect a sample to test. You may be able to take the swab yourself or a doctor or nurse may do it
• You may sometimes be asked for a urine sample to test

If you have a penis

• You’ll usually be asked to give a urine sample to test. Before a urine test, you’re advised not to pass urine (pee) for 1 to 2 hours
• A doctor or nurse may take a swab from the entrance of the urethra (tube you pee from) to test

Other parts of the body

• If you’ve had anal or oral sex, a doctor or nurse may swab your rectum (back passage) or throat to test for chlamydia or you may be asked to swab yourself. These swabs are not done routinely on everyone
• If you have symptoms of conjunctivitis (an eye infection) swabs will be used to collect a sample of discharge from your eye(s) to test for chlamydia

A swab is like a long, thin cotton bud. It sometimes has a small plastic loop on the end rather than a cotton tip. It’s wiped over body parts that could be infected.This only takes a few seconds and isn’t painful, though it may be uncomfortable for a moment.

Cervical screening (smear tests) and routine blood tests don’t detect chlamydia.

If you’re not sure if you’ve been tested for chlamydia, just ask.

If you have a test at a clinic or GP surgery, you’ll usually have to wait 1 to 2 weeks. The clinic or surgery will let you know when and how to expect your result.

If you use an online testing service, you’ll usually get your results within 1 week from when the service receives your sample.

The accuracy of a test depends on the kind of test used, the type of sample that’s collected, and which part of your body the sample is collected from.

Chlamydia tests done by trained healthcare professionals or done according to instructions from an online testing service provided by your local sexual health service are usually highly accurate.

As no test is 100% accurate there’s a small chance that the test will give a negative result when you do have chlamydia. This is known as a false negative result. This can sometimes explain why you might get a different result from another test or why you and a partner might get a different test result.

It’s possible, but unlikely, for a chlamydia test to be positive if you haven’t got chlamydia. If there are any doubts about the result you may be offered a second test.

There are different services you can go to. Choose the one you feel most comfortable with.

A free chlamydia test can be done at:

• a sexual health clinic or genitourinary medicine (GUM) clinic
• some GP surgeries
• some contraception and young people’s clinics
• some pharmacies

Abortion clinics, antenatal services and some gynaecology services may offer a test.

Free home self-sampling tests

In many areas, free home tests for chlamydia are available to order online from your local sexual health service. You take your own sample (self-sampling) and send it to be tested. These tests are usually only for people without symptoms. If you have symptoms, always get tested at a sexual health service.

Buying a test

It’s also possible to buy chlamydia tests from pharmacies and other private providers. These may be self-sampling tests or home tests that give you the result in a few minutes. The accuracy of these tests varies. If you choose to buy a testing kit, it’s a good idea to get advice from a pharmacist or your doctor. You can also choose to pay for a chlamydia test at a private clinic.

If a self-sampling test or home test shows that you have chlamydia, it’s important to seek treatment straight away. The test should have instructions explaining what to do.

Buying a Self-sampling Test from the FPA

A STI Four Screen Self-Sampling Test Kit is available here – this test covers gonorrhoea, chlamydia, HIV and syphilis.

Before buying a test it’s worth checking if there are free tests available in your area first.

National Chlamydia Screening Programme (NCSP)

In England, women and other people who have a womb or ovaries, who are aged under 25, may be offered a chlamydia test as part of the NCSP when you visit services such as a pharmacy or your GP.

The NCSP aims to reduce health harm caused by untreated chlamydia. Untreated chlamydia in
women can cause pelvic pain, ectopic pregnancy, and infertility – also see below for Will chlamydia affect my fertility? If you’re offered a chlamydia test as part of the NCSP, do consider taking it.

All tests are free through NHS services or the National Chlamydia Screening Programme. All chlamydia treatment from these services is also free.

Chlamydia is treated with antibiotics.

• You’ll usually be given antibiotics to take for 7 days. Some people may be offered a different antibiotic to take for 3 days. Occasionally, you may need a longer course of up to 2 weeks
• If you take the treatment according to instructions, it’s over 95% effective
• If there’s a high chance you have chlamydia, treatment may be started before the test results are back
• You may also need other treatment if complications have occurred
• Tell the doctor or nurse if you’re pregnant, or think you might be, or you’re breastfeeding. This may affect the type of antibiotic you’re given
• Complementary therapies (treatments outside of mainstream healthcare) can’t cure chlamydia

Most people notice an improvement quite quickly after having treatment. It’s important to finish all your treatment, even if symptoms go away.

• Discharge or pain when you urinate (pee) should improve within about a week
• Bleeding between periods or heavier periods caused by chlamydia should improve by your next period.
• Pelvic pain and pain in the testicles should start to improve quickly but may take up to 2 weeks to go away

If you have pelvic pain or painful sex that doesn’t improve, see your doctor or nurse. It may be necessary to have some further treatment or investigate other possible causes of the pain.

If you take the treatment according to the instructions, you won’t usually need a test to check the chlamydia has gone.

If you’re aged under 25, you should be offered a repeat test 3 to 6 months after finishing the treatment. This is because you’re more likely to get chlamydia again.

If the chlamydia was in your rectum (back passage), you may need another test around 3 weeks after finishing the treatment. Your doctor, nurse or clinic will let you know if you need another test.

Whatever your age, you may need a repeat test or more treatment if:

• you think you’ve come into contact with chlamydia, or another STI, again
• you had sex with a partner before the treatment for both of you was finished
• you didn’t complete the treatment or didn’t take it according to the instructions
• the signs and symptoms don’t go away
• your test was negative but you develop signs or symptoms
• you’re pregnant.

A repeat chlamydia test can be done 5 to 6 weeks after the first test.

Only some people who have chlamydia will have complications.

If treated early, chlamydia is unlikely to cause any long-term problems. But, without effective treatment, the infection can spread to other parts of the body and cause health complications.

The more times you have chlamydia the more likely you are to get complications.

Chlamydia is more likely to cause serious complications in people with a vagina/front hole.

• If you have a vagina/front hole, chlamydia can spread to other reproductive organs causing pelvic inflammatory disease (PID). This can lead to long-term pelvic pain, blocked fallopian tubes, ectopic pregnancy (when the pregnancy develops outside the uterus), and infertility.
• In people with a vagina/front hole, chlamydia can cause pain and inflammation around the liver, though this is rare. This usually gets better with the correct antibiotic treatment.
• If you have a penis, chlamydia can lead to a painful infection in the testicles. If this isn’t treated, it can cause long-term pain and, very rarely, there’s a possibility it could affect your fertility.
• It’s not common, but chlamydia can lead to inflammation (pain and swelling) of the joints and tendons, known as Sexually Acquired Reactive Arthritis (SARA). SARA may sometimes cause inflammation of the urethra (tube you pee from) or the eyes. It’s more common in people with a penis than people with a vagina/front hole.

Chlamydia may eventually go away, but it can take a long time.

If you delay seeking treatment, even if signs and symptoms go away, chlamydia could cause long-term damage and you may pass the infection on to someone else.

Don’t have any vaginal/frontal, anal or oral sex (even with condoms), or share sex toys, until you and your partner(s) have finished the treatment and any symptoms have gone.

Depending on the antibiotics used, you may also need to wait a few more days after finishing the treatment. This helps to stop you being reinfected or passing the infection on to someone else.

• If you have an antibiotic called doxycycline wait until the treatment is finished and any symptoms have gone
• If you have an antibiotic called azithromycin wait until 7 days after starting the treatment as that’s how long it takes to work, and until any symptoms have gone

A chlamydia test can’t tell you how long you’ve had chlamydia for.

If you feel upset or angry about having chlamydia and find it difficult to talk to a partner or friends, don’t be afraid to discuss how you feel with the staff at the clinic or GP surgery.

If you have chlamydia it’s very important that your current sexual partner(s) and any other recent partners are tested and treated as they may have the infection without knowing it.

This will help to stop them reinfecting you or passing the infection on to anyone else.

You may be given a contact slip to send or give to your partner(s) or, with your permission, the clinic can do this for you. This is called partner notification. It can sometimes be done by text message. The message or contact slip will say that they may have been exposed to a sexually transmitted infection and suggest they go for a check-up. It may or may not say what the infection is. It won’t have your name on it, so your confidentiality is protected.

You’re strongly advised to tell your partner(s), but it isn’t compulsory. The staff at the clinic, GP surgery or online service can discuss this with you.

Chlamydia is just one of many factors that can affect your fertility.

Most people who’ve had chlamydia won’t become infertile or have an ectopic pregnancy.

If you’ve had chlamydia you won’t normally be offered any routine tests to see if you’re fertile unless you or a partner are having difficulty getting pregnant. If you’re concerned, talk to your doctor or practice nurse.

Chlamydia can be treated with antibiotics when you’re pregnant or breastfeeding. The antibiotics won’t harm the baby but do tell the doctor or nurse that you’re pregnant or breastfeeding.

• Chlamydia can be passed to the baby during the birth and (less commonly) before the baby is born. This can cause inflammation and discharge in the baby’s eye(s) (conjunctivitis) and/or pneumonia.
• Chlamydia during pregnancy has been associated in very rare cases with problems such as premature (early) birth, and infection of the uterus (womb) lining after the birth. You may be offered a chlamydia test as part of your antenatal care.
• You’ll be advised to have a test after you complete your treatment to check the chlamydia has gone

No, chlamydia doesn’t cause cervical cancer.

The following measures will help protect you from getting and passing on chlamydia and most other sexually transmitted infections (STIs), such as HIV, syphilis and gonorrhoea.