Chlamydia is one of the most common sexually transmitted infections (STIs). It is very easy to treat and cure. Up to one in ten sexually active young people are thought to have chlamydia. If left untreated it can cause painful complications and serious health problems such as infertility.

What causes chlamydia?

Chlamydia trachomatis is a bacteria, which is found in the semen and vaginal fluids of men and women who have the infection. Chlamydia is easily passed from one person to another through sexual contact. Anyone who is sexually active can get it and pass it on. You don’t need to have lots of sexual partners.

How is chlamydia passed on?

Chlamydia is usually passed from one person to another during sex. You can become infected with chlamydia if you come into contact with the semen or vaginal fluids of someone who already has the infection.

The bacteria can live inside the cells of the cervix (entrance to the womb), the urethra (tube where urine comes out), the rectum (back passage) and sometimes the throat and eyes.

The infection is most commonly spread through:

• unprotected vaginal, anal or oral sex
• sharing sex toys if you don’t wash them or cover them with a new condom each time they’re used.

Infected semen or vaginal fluid coming into contact with the eye can cause conjunctivitis.

Chlamydia can also be passed from a pregnant woman to her baby.

It is not yet 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 catch chlamydia from kissing, hugging, sharing baths or towels, swimming pools, toilet seats or from sharing cups, plates or cutlery.

What are the signs and symptoms?

About 70–80 per cent of infected women and over 50 per cent of men will not have any obvious signs or symptoms or they may be so mild they are not noticed.

Signs and symptoms can show up one to three weeks after coming into contact with chlamydia, many months later, or not until the infection spreads to other parts of your body. You might notice:

Women

• bleeding between periods and/or heavier periods (including women who are using hormonal contraception)
• bleeding after sex
• pain and/or bleeding when you have sex
• lower abdominal pain (pelvic pain)
• an unusual vaginal discharge
• pain when passing urine

Men

• a white/cloudy or watery discharge from the tip of the penis
• pain when passing urine
• possible pain of the testicles.

Men and women

There are rarely any symptoms if the infection is in the rectum but it may cause discomfort, and discharge.

Infection in the eyes can cause pain, swelling, irritation and discharge (conjunctivitis).

Infection in the throat is uncommon and usually has no symptoms.

How will I know if I have the infection?

You can only be certain you have chlamydia if you have a test so don’t delay in getting a test. The National Chlamydia Screening Programme in England shows that risk factors for chlamydia increase if you are under 25, have a new sexual partner, or more than one sexual partner in the last year, and have not used condoms.

You may wish to have a test if:

• you or your partner have or think you might have symptoms
• you have recently had unprotected sex with a new partner
• you or your partner have had unprotected sex with other partners
• during a vaginal examination your doctor or nurse says that the cells of the cervix are inflamed or there is a discharge
• a sexual partner tells you they have a sexually transmitted infection
• you have another sexually transmitted infection
• you are pregnant or planning a pregnancy.

You could still have chlamydia even if your partner has tested negative – you cannot always rely on a partner’s negative test result.

If you have chlamydia you may wish to be tested for other sexually transmitted infections as you can have more than one sexually transmitted infection at the same time. Having an infection such as chlamydia can mean you are more at risk of becoming infected with HIV. See Where can I get more information and advice?.

How soon after sex can I have a test?

It is important not to delay getting a test if you think you might have chlamydia. It is possible to do a chlamydia test straightaway. Sometimes you may be advised to have a test one to two weeks after having sex. You can have a test for chlamydia even if there are no symptoms.

What does the test involve?

There are different ways of testing for chlamydia.

Women

• You may be asked to use a swab or a tampon yourself to collect cells from inside the vagina.
• A doctor or nurse may use a swab to collect a sample of cells from the cervix during an internal examination, or from the vagina.

Men and women

• You may be asked to provide a urine sample (this is usually the test offered to men). Before having this test you may be advised not to pass urine for 1– 2 hours.
• A doctor or nurse may use a swab to collect a sample of cells from the entrance of the urethra.
• If you have had anal or oral sex the doctor or nurse may use a swab to collect cells from your rectum and throat. These swabs are not done routinely.
• If you have symptoms of conjunctivitis – discharge from the eye(s) – swabs will also be used to collect cells from your eye(s).

A swab looks a bit like a cotton bud, but is smaller and rounded. It is wiped over the parts of the body that could be infected and easily picks up samples of discharge and cells. This only takes a few seconds and is not painful, though it may be uncomfortable for a moment.

Cervical screening tests and routine blood tests do not detect chlamydia. If you are not sure whether you have been tested for chlamydia, just ask.

How accurate are the tests?

The accuracy of chlamydia tests depends on the kind of test used and the type of sample that is collected. The recommended tests are over 90 per cent accurate in picking up the infection. As no test is 100 per cent accurate there is a small chance that the test will give a negative result when you do have the infection. This is known as a false negative result. This can sometimes explain why you might get a different result when you go to a different clinic to have another test or why you and your partner might get a different test result.

It is possible for the test to be positive if you haven’t got chlamydia, but this is rare.

Where can I get a test?

There are a number of services you can go to. Choose the service you feel most comfortable with.

A chlamydia test can be done at:

• a genitourinary medicine (GUM) or sexual health clinic
• your general practice
• contraceptive and young people’s clinics.

For information on how to find a service see Where can I get more information and advice?

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

In addition, The National Chlamydia Screening Programme in England offers free tests to men and women under 25 who have ever been sexually active. Under this programme tests are also available from places such as colleges, youth clubs, military bases, some pharmacies and other places which are convenient for young people to use. The screening programme is usually advertised locally.

It is possible to buy a chlamydia test to do at home. The accuracy of these tests varies. Some are very accurate when carried out according to the instructions, others can be less reliable. If you buy a self-testing kit make sure you get good advice from the pharmacist or your doctor.

You can also choose to pay for a chlamydia test at a private clinic.

Will I have to pay for tests and treatment?

All tests are free through NHS services and the National Chlamydia Screening Programme. Treatment is also free but if you go to your general practice you may have to pay a prescription charge for some treatment.

What is the treatment for chlamydia?

The common treatment for chlamydia is a course of antibiotics which, if you take it according to the instructions, is at least 95 per cent effective.

• Early treatment of chlamydia involves taking a course of antibiotic tablets either as a single dose or a longer course (up to two weeks).
• If there is a high chance you have the infection, treatment may be started before the results of the test are back. You will always be given treatment if your partner is found to have chlamydia.
• You may also need other treatment if complications have occurred.
• Do tell the doctor or nurse if you are pregnant, or think you might be, or you are breastfeeding. This will affect the type of antibiotic that you are given.
• The antibiotics that are used to treat chlamydia interact with the combined contraceptive pill and the contraceptive patch. Tell the doctor or nurse if you are using these methods so they can advise you on how to ensure you are protected from pregnancy.
• There is currently no evidence that complementary therapies can cure chlamydia.

When will the signs and symptoms go away?

You should notice an improvement in the signs and symptoms quite quickly.

• Discharge or pain when you urinate should improve within a week.
• Bleeding between periods or heavier periods that have been caused by chlamydia should have improved by your next period.
• Pelvic pain and pain in the testicles should start to improve quickly but may take up to two weeks to go away.

If you have pelvic pain or painful sex that does not improve see your doctor or nurse as it may be necessary to have some further treatment or investigate other possible causes of the pain.

Do I need to have a test to check that the chlamydia has gone?

If you take the treatment according to the instructions you will not normally need a follow-up test. You should however go back to the clinic if:

• you think you may have come into contact with chlamydia again
• you had unprotected sex with your partner before the treatment was finished (see How soon can I have sex again?)
• you were given a course of treatment that is less than 95 per cent effective
• you did not complete the treatment or did not take it according to the instructions
• the signs and symptoms don’t go away (see When will the signs and symptoms go away?)
• your test was negative but you develop signs or symptoms of chlamydia (see What are the signs and symptoms?)

In these situations you may need a repeat test (which can be done five to six weeks after the first test) and/or you may need another course of antibiotics. If you were treated for chlamydia in early pregnancy you may be advised to have another test if you’ve had a new sexual partner.

You can always go back to the doctor, nurse or clinic if you have any questions or need any advice on how to protect yourself from infection in the future.

What happens if chlamydia isn't treated?

If chlamydia is treated early it is unlikely to cause any long-term problems. Not everyone who has chlamydia has complications. However, without proper treatment the infection can spread to other parts of the body. The more times you have chlamydia the more likely you are to get complications.

• In women, chlamydia can spread to other reproductive organs causing pelvic inflammatory disease (PID). This can lead to long-term pelvic pain, blocked fallopian tubes, infertility and ectopic pregnancy (when the pregnancy develops outside the womb, usually in a fallopian tube). In women chlamydia can also spread to the liver causing pain and inflammation. This usually gets better with the correct antibiotic treatment.
• In men chlamydia can lead to a painful infection in the testicles and possibly reduced fertility.
• Rarely, chlamydia can lead to inflammation of the joints in both men and women. This is known as reactive arthritis and it is sometimes accompanied by inflammation of the urethra and the eye when it is known as Reiter's Syndrome. This is more likely to occur in men than women.

Can chlamydia go away without treatment?

It can, but it is unlikely. If you delay seeking treatment you risk the infection causing long-term damage and you may still be able to pass the infection on to someone else.

How soon can I have sex again?

It is strongly advised that you do not have vaginal, anal or oral sex until you and your partner have both finished the treatment, otherwise you could be re-infected or pass the infection on to someone else. If you are given antibiotic treatment called azithromycin that you take for only one day you will need to avoid sex for seven days after you have taken the tablets. If it is not possible to avoid sex, make sure that you use a condom.

Will I know how long I've had the infection?

If you have had more than one sexual partner it can be difficult to know which partner you got chlamydia from. The chlamydia test cannot tell you how long the infection has been there. If you feel upset or angry about having chlamydia and find it difficult to talk to your partner or friends, don’t be afraid to discuss how you feel with the staff at the clinic or general practice.

Should I tell my partner?

If the test shows that you have chlamydia then it is very important that your current sexual partner and any other recent partners are also tested and treated. The staff at the clinic or general practice can discuss with you which of your sexual partners may need to be tested.

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. The slip explains that they may have been exposed to a sexually transmitted infection and suggests that they go for a check-up. It may or may not say what the infection is. It will not have your name on it, so your confidentiality is protected. This is called partner notification. You are strongly advised to tell your partner(s), but it isn’t compulsory.

How will I know if the chlamydia has affected my fertility?

Chlamydia is just one of many factors that can affect your fertility. Many women who have had chlamydia will not become infertile or have an ectopic pregnancy (see What happens if chlamydia isn’t treated?). If you have had chlamydia you will not normally be offered any routine tests to see if you are fertile unless you or your partner are having difficulty in getting pregnant. If you are concerned, talk to your doctor or practice nurse.

What happens if I get chlamydia when I'm pregnant?

Chlamydia may be linked to early miscarriage or premature birth of the baby.

• It 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 can be treated with antibiotics when you are pregnant and when you are breastfeeding – the antibiotics won’t harm the baby, but do tell the doctor or nurse that you are pregnant.
• You may be offered a chlamydia test as part of your antenatal care.

Does chlamydia cause cervical cancer?

Currently there is no clear evidence that chlamydia causes cervical cancer. Research is still ongoing.

How can I protect myself from chlamydia?

Use condoms (male or female) every time you have vaginal or anal sex.

• If you have oral sex, cover the penis with a condom or the female genitals with a latex or polyurethane (plastic) square (dam).
• If you are not sure how to use condoms correctly see our information on Where can I get more information and advice?
• Avoid sharing sex toys. If you do share them, wash them or cover them with a new condom before anyone else uses them.

These measures can also help to protect you from some other STIs such as HIV, and gonorrhoea. If you have chlamydia without knowing it they will also help prevent you from passing it on to your partner.