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.
This page gives you information about chlamydia, what you can do if you are worried that you might have the infection and advice on how to protect yourself.
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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.
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 uterus – 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:
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 (see What happens if I get chlamydia when I’m pregnant?)
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.
About 70 per cent of infected women and 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:
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.
You can only be certain you have chlamydia if you have a test so don’t delay in getting a check-up.
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 could still have chlamydia even if a 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.
It is important not to delay going for a check-up if you think you might have chlamydia. A test can be carried out straightaway but you may be advised to have another test two weeks after having sex. You can have a test for chlamydia even if there are no symptoms.
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.
The accuracy of a chlamydia test 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 a 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.
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:
For information on how to find a service see How to get help with your sexual health.
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 types 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 advice from the pharmacist or your doctor.
You can also choose to pay for a chlamydia test at a private clinic.
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 treatment.
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.
You should notice an improvement in the signs and symptoms quite quickly.
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.
If you take the treatment according to the instructions you will not normally need a follow-up test. However, you should go back to the clinic if:
In these situations you may need a repeat test (which can be done 5–6 weeks after the first test). You may need another course of antibiotics.
If you were treated for chlamydia in pregnancy you may be advised to have another test.
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.
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.
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.
Do not have oral, vaginal or anal sex, or use sex toys, until seven days after you and your partner have both finished the treatment and any symptoms have gone. This is to help prevent you being re-infected or passing 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 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 a partner or friends, don’t be afraid to discuss how you feel with the staff at the clinic or general practice.
If the test shows that you have chlamydia then it is very important that your current sexual partner(s) 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.
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.
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.
There is no evidence that chlamydia causes cervical cancer.
It is possible to get chlamydia and other sexually transmitted infections by having sex with someone who has the infection but has no symptoms.
The following measures will help protect you from chlamydia and most other sexually transmitted infections including HIV. If you have a sexually transmitted infection without knowing it they will also help prevent you from passing it on to a partner.
Last updated November 2012. Next update available October 2013.