Genital chlamydia (just referred to as chlamydia from now on in this leaflet) is the most common sexually transmitted infection in the UK. It often causes no symptoms, and can be passed on to others without you realising. However, symptoms and complications may develop if it is left untreated. A short course of an antibiotic medicine clears the infection in most cases.
What is chlamydia?
Chlamydia is an sexually transmitted infection caused by a germ (bacterium) called Chlamydia trachomatis. In women, chlamydial infection usually affects the neck of the womb (cervix) and the womb (uterus). In men, it usually affects the pipe through which urine is passed (the urethra) in the penis. Chlamydia sometimes causes infection of the eye, throat, and lungs.
How do you get chlamydia and how common is it?
Most people with chlamydia get the infection by having sex with an infected person. You can become infected with chlamydia if you come into contact with the semen or vaginal fluids of a person who has chlamydia.
About 1 in 20 sexually active women in the UK are infected with chlamydia. It is most common in women aged under 25. (About 1 in 12 women aged 20 are infected with chlamydia.) The number of cases has risen sharply in recent years. Many women are not aware that they are infected, as it often causes no symptoms. You can be infected with chlamydia for months, even years, without realising it. The risk of infection increases with the number of changes of sexual partner. Wearing a condom during sex helps to prevent chlamydia and other sexually transmitted infections.
Note: you can not catch chlamydia from hugging, kissing or from sharing cups or cutlery.
What are the common symptoms of chlamydia?
No symptoms occur in around 7 in 10 infected women and 5 in 10 infected men. Also, you may not have any symptoms until several weeks (or even months) after coming into contact with chlamydia.
If symptoms do occur in women, they may include:
- Vaginal discharge. This is due to the neck of the womb (cervix) becoming inflamed.
- Pain or burning when you pass urine.
- Vaginal bleeding or spotting between periods. In particular, bleeding after you have sex.
- Pain or discomfort in the lower tummy (abdomen) area (the pelvic area), especially when you have sex.
If symptoms do occur in men, they may include:
- Pain or burning when you pass urine.
- Discharge from the end of your penis.
- Pain or discomfort at the end of your penis.
Do I need any tests?
Chlamydia can be confirmed by a swab taken from the neck of the womb (cervix) in women and, in men, from the the pipe through which urine is passed (the urethra) in the penis. Recent evidence suggests that a high vaginal swab (taken from high up in the vagina) is as good if not better than a swab taken from the cervix . A swab is a small ball of cotton wool on the end of a stick which is used to obtain mucus and cells to send to the laboratory for testing. Alternatively, you may be asked to provide a urine sample. This is usually from the first time you pass urine in the day. The urine is tested for chlamydia. If you have had anal or oral sex then you may have a back passage (rectal) or throat swab taken. The tests for chlamydia are only around 90% accurate. This means that you can actually have chlamydial infection even if your test is negative.
You may also be advised to be tested for other sexually transmitted infections.
Note: the cervical screening test does not test for chlamydia.
What is the treatment for chlamydia?
It is important that treatment for chlamydia should be started without delay. In some people where chlamydia is strongly suspected, this may even mean starting treatment before test results are available. Prompt treatment reduces the risk of complications in the future.
A short course of an antibiotic medicine usually clears chlamydial infection. You should tell your doctor if you are (or may be) pregnant or are breast-feeding. This may affect the choice of antibiotic. You should not have sex until you and your sexual partner have finished treatment (or for seven days after treatment with a single-dose antibiotic).
Note: antibiotics can interfere with the combined oral contraceptive pill (COCP). If you take the COCP you should use alternative methods of contraception until seven days after finishing a course of antibiotics.
Does my partner need to be treated?
Yes. Also, any other sexual partners within the previous six months should also be tested for infection. If you have not had sex within the previous six months then your latest sexual partner should be tested and treated, however long ago the relationship was.
If your sexual partner is infected and not treated, then chlamydia can be passed back to you again after you are treated.
In some occasions, you may not want to contact partners from previous relationships. In these cases then staff at the clinic can contact previous partners for you without disclosing your details. This is because it is important that anyone who is at risk of infection with chlamydia is both identified and treated.
Why should I have treatment if I have no symptoms?
If you are infected with chlamydia, it is essential that you take treatment even if you do not have any symptoms of chlamydial infection. Reasons for this include:
- The infection may spread and cause serious complications (see below). This can be months or years after you are first infected.
- You can still pass on the infection to your sexual partner(s) even if you do not have symptoms.
Do I need to be tested again after treatment?
You do not usually need to have another test if you have taken an antibiotic medicine correctly. However, it is advisable to have another test for chlamydia in the following situations:
- If you think you have had sex with a person with chlamydia.
- If your symptoms do not improve after treatment.
- If you had unprotected sex before you finished the treatment.
What are the possible complications of chlamydia?
- If left untreated, the infection may seriously affect the womb (uterus) and Fallopian tubes - this is called pelvic inflammatory disease (PID). About 2-5 women in 100 with chlamydia develop PID. This may develop suddenly and cause a high temperature (fever) and pain. It can also develop slowly over months or years without causing symptoms (also known as silent PID). However, over time, scarring or damage to the Fallopian tubes may occur and can cause:
- Chronic (persistent) pelvic pain.
- Difficulty becoming pregnant (infertility).
- If you become pregnant, you have an increased risk of ectopic pregnancy. In this condition, the pregnancy develops in a Fallopian tube and can cause serious life-threatening problems.
- The risk of developing some complications of pregnancy, such as miscarriage, premature birth and stillbirth, is increased in pregnant women with untreated chlamydia.
- If you have untreated chlamydia during childbirth, your baby may develop a chlamydial infection of their eye or lung during the birth.
- Possibly reduced fertility in men.
- Reiter's syndrome is a rare complication which can occur in both men and women. This causes arthritis and eye inflammation. It may be due to the immune system 'over-reacting' to chlamydial infection in some cases.
The risk of complications is much reduced if chlamydial infection is treated early.
Who can be screened for chlamydia?
The National Chlamydia Screening Programme was introduced in England. This offers chlamydial screening for sexually active women and men, aged under 25 years, to be undertaken yearly or when they change sexual partners. The aims of this programme are to detect chlamydia early so it can be treated promptly. This should reduce the risk of transmission and also reduce the risk of developing complications.
Certain other groups of people are also recommended to undergo screening for chlamydia. For example, if you have a partner with chlamydia, if you have another sexually transmitted infection, or if you are a semen or egg donor.
Men will be asked to give a urine sample and women can either give a urine sample or take a swab. A swab is a small ball of cotton wool on the end of a stick, used to take a sample of mucus and cells for laboratory testing. Women can take the swab themselves from the lower vagina.
Further help & information
Further reading & references
- Sexually Transmitted Infections in Primary Care; Royal College of General Practitioners and British Association for Sexual Health and HIV (Apr 2013)
- National Chlamydia Screening Programme; Public Health England
- Gobin M, Verlander N, Maurici C, et al; Do sexual health campaigns work? An outcome evaluation of a media campaign to increase chlamydia testing among young people aged 15--24 in England. BMC Public Health. 2013 May 17;13(1):484.
- Management of genital Chlamydia trachomatis infection; Scottish Intercollegiate Guidelines Network - SIGN (March 2009)
- Haggerty CL, Gottlieb SL, Taylor BD, et al; Risk of sequelae after Chlamydia trachomatis genital infection in women. J Infect Dis. 2010 Jun 15;201 Suppl 2:S134-55. doi: 10.1086/652395.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Tim Kenny
Dr Laurence Knott
Dr Helen Huins