Sexually transmitted infections (STIs) – Chlamydia


Sexually transmitted infections (STIs) – Chlamydia


Chlamydia is one of the most common sexually transmitted infections (STIs) in the UK.

It’s passed on from one person to another through unprotected sex (sex without a condom).

In 2012, 206,912 people tested positive for chlamydia in England. 64% of people diagnosed with chlamydia were under 25 years old.


Chlamydia symptoms

Most people who have chlamydia don’t notice any symptoms, and so don't know they have it. Research suggests that 50% of men and 70-80% of women don't get symptoms at all with a chlamydia infection. 

Symptoms of chlamydia could be pain when you urinate (pee), unusual discharge from the penis, vagina or rectum or, in women, bleeding between periods or after sex.


Getting tested for chlamydia

Testing for chlamydia is done with a urine test or a swab test. You don't always have to have a physical examination by a nurse or doctor.

Anyone can get a free and confidential chlamydia test at a sexual health clinic, a GUM (genitourinary medicine) clinic or a GP surgery. Find out more about getting a chlamydia test.

People under 25 years old can also get tested by the National Chlamydia Screening Programme (NCSP). This is often in places such as pharmacies, contraception clinics or colleges.

You can also buy chlamydia testing kits to do at home, however, the accuracy of these tests varies. If you use one of these tests, talk to your pharmacist or GP.


Treating chlamydia

Chlamydia is easily treated with antibiotics. You may be given a single dose, or a longer course of antibiotics to take for a week.

If chlamydia isn’t treated, the infection can sometimes spread to other parts of your body and lead to serious long-term health problems such as pelvic inflammatory disease and infertility (not being able to have children).


The National Chlamydia Screening Programme

Chlamydia is most common in people under 25 years old, although people of any age can get it. If you are under 25, you can get a free, confidential chlamydia test under the National Chlamydia Screening Programme (NCSP). This offers tests in various places, including some pharmacies. Find your nearest NCSP testing site.

Some NCSP areas may also send chlamydia testing kits to you through the post. You can request these online. Find out about free online chlamydia tests for under 25s.

Find out answers to some common questions about chlamydia:

Can chlamydia be caught only through sexual contact?

How soon do STI symptoms appear?

What should I do if I think I've got an STI?


Symptoms of chlamydia 

Most people who have chlamydia don’t notice any symptoms.

If you do get signs and symptoms, these usually appear between one and three weeks after having unprotected sex with an infected person. For some people the symptoms occur many months later, or not until the infection has spread.


Symptoms in women

Around 70-80% of women with chlamydia don't notice any symptoms. If women do get symptoms, the most common include: 

pain when urinating (peeing)

a change in vaginal discharge

pain in the lower abdomen

pain and/or bleeding during sex

bleeding after sex

bleeding between periods

heavier periods than usual

If chlamydia is left untreated in women, it can spread to the womb and cause pelvic inflammatory disease (PID). PID is a major cause of infertility, miscarriage and ectopic pregnancy.


Symptoms in men

Around half of all men with chlamydia don't notice any symptoms. If men do get symptoms, the most common include: 

pain when urinating (peeing)

discharge from the tip of the penis (this can be a white, cloudy or watery discharge)

pain in the testicles

Some men have mild symptoms that disappear after two or three days. Even if the symptoms disappear you will still have the infection and be able to pass it on. If chlamydia is left untreated in men they are at risk of complications of chlamydia such as orchitis (swollen testicles), reactive arthritis, and infertility.


Chlamydia in the rectum, throat or eyes

Chlamydia can infect the rectum, eyes or throat if you have unprotected anal or oral sex. If infected semen or vaginal fluid comes into contact with the eyes you can also develop conjunctivitis.

Infection in the rectum can cause discomfort, pain, bleeding or discharge. In the eyes, chlamydia can cause irritation, pain, swelling and discharge the same as conjunctivitis. Infection in the throat is less common and usually causes no symptoms.

Search for sexual health clinics near you.

Find out more about:

getting tested for chlamydia

chlamydia treatment

complications of chlamydia

protecting yourself against chlamydia


If you're under 25

If you are sexually active and under 25 years old, you should get tested for chlamydia every year or every time you have a new partner. the National Chlamydia Screening Programme can offer testing near you.


Causes of chlamydia 

Chlamydia is caused by bacteria called Chlamydia trachomatis.

Chlamydia is a sexually transmitted infection (STI), which means that you get it through having unprotected sex (sex without a condom) with someone who has chlamydia.


How you get chlamydia

You can get chlamydia through: 

unprotected vaginal sex

unprotected anal sex

unprotected oral sex

your genitals coming into contact with your partner's genitals

sharing sex toys when they are not washed or covered with a new condom between each person who uses them

Sexual fluid from the penis or vagina can pass chlamydia from one person to another even if the penis does not enter the vagina, anus or mouth. This means you can get chlamydia from genital contact with someone who has the infection even if there is no penetration, orgasm or ejaculation.

It isn’t clear if chlamydia could be passed on by transferring infected semen or vaginal fluid on the fingers, or by rubbing female genitals together.

Chlamydia cannot be passed on through casual contact, including kissing and hugging, or from sharing baths, towels, swimming pools, toilet seats or cutlery.

Infected semen or vaginal fluid can cause conjunctivitis if it gets into someone’s eye.


Chlamydia and giving birth

During childbirth, a woman with chlamydia can pass the infection on to her baby. If chlamydia develops in the baby there might not be any obvious symptoms at first. Chlamydia in a newborn baby can cause inflammation (swelling) and discharge in the baby’s eyes (known as conjunctivitis) and pneumonia. The midwife or GP can arrange a simple swab test for chlamydia from the baby.

Find out more about:

chlamydia symptoms

getting tested for chlamydia

chlamydia treatment

protecting yourself against chlamydia


Diagnosing chlamydia 

The only way to find out if you have chlamydia is to get tested. You can get tested whether or not you have symptoms.


What does the chlamydia test involve?

The tests for chlamydia are simple and painless. Most people can have the test carried out using a urine sample. Some people have a swab test (a small cotton bud). The swab is used to gently wipe the area where you might have chlamydia, to collect some cells. The cells are then tested for infection.

The doctor or nurse will explain which is the best test for you to have. You don’t always have to be examined by the doctor or nurse – this will depend on your situation and where you go to get tested.

People who have had anal or oral sex might have a swab taken from their rectum or throat. This isn’t done on everyone.

If you have symptoms in your eye, such as discharge or inflammation, a swab test might be taken to collect cells from your eyelid.


Tests for women

Chlamydia tests on women can be done with a urine sample or swab test. If a woman has a swab test, it can be taken from the cervix, or inside the lower vagina. Occasionally the doctor or nurse may advise you to have a swab test from the urethra (where urine comes out). Usually you can do a lower vaginal swab yourself, although sometimes a nurse or doctor may do it.

If you have had anal or oral sex you might also be offered a swab test taken from the rectum or throat. This isn’t done on everyone.

Cervical screening tests (smear tests) and routine blood tests do not detect chlamydia. You will need to tell the doctor or nurse if you would also like to be tested for chlamydia at the same time.


Tests for men

Men will usually have a chlamydia test on a urine sample. Occasionally, a swab test may be taken from the urethra (the tube where urine comes out) at the tip of the penis.

If you have had anal or oral sex you might also be offered a swab test taken from the rectum or throat. This isn’t done on everyone.


How soon after sex can I get a chlamydia test?

Don't delay getting tested if you think you might have chlamydia.

You can get a chlamydia test at any time whether or not you have symptoms. You might be advised to repeat the test if it was less than two weeks since you had sex, as sometimes the infection could be in its early stages.

It is recommended that you get tested for chlamydia if:

you or your partner think you have any symptoms

you've had unprotected sex with a new partner

you’ve had a split condom

you or your partner have unprotected sex with other people

you think you have a sexually transmitted infection (STI)

a sexual partner tells you they have an STI

you're pregnant or planning a pregnancy

you have a vaginal examination and your doctor or nurse tells you that the cells of your cervix are inflamed or there is vaginal discharge

Don’t put off having a test for chlamydia – getting diagnosed and treated as soon as possible will reduce the risk of developing any complications of chlamydia. Complications that occur because of long-term chlamydia infection are more difficult to treat.


Where can I get a chlamydia test?

Anyone can get a free confidential chlamydia test at:

a sexual health clinic

a GUM (genitourinary medicine) clinic

your GP surgery

most contraceptive clinics

People under 25 years old can also get tested by the National Chlamydia Screening Programme (NCSP). This is often in places such as pharmacies, colleges or young people's services.

You can go to whichever place is the most comfortable and convenient for you.

You can also buy chlamydia testing kits to do at home. The accuracy of these varies. If you use one of these tests, talk to your pharmacist or GP.


What happens at a sexual health clinic?

Some clinics are walk-in, at others you may need to book an appointment. Ring first to find out.

When you attend a clinic, you will be registered as a patient. This is confidential, and your details will not be passed on to your GP unless you request it.

You will be asked some questions about why you have attended the clinic and your sexual history. Questions might include when you last had sex, whether you used condoms and whether you have had an STI before.

You will be offered routine tests for gonorrhoea, HIV, syphilis and chlamydia. HIV and syphilis are tested using blood samples. Gonorrhoea and chlamydia are tested using either swab or urine tests. 


How reliable is a chlamydia test?

The accuracy of tests varies, depending on the type of test used. Recommended tests are 90-95% sensitive. This means that they will detect chlamydia in most people who have the infection. Some tests you can buy may be less reliable.

Remember that no test is 100% accurate. There is a small chance that a test may show negative even when you have chlamydia. This is called a false negative test result. It is also possible for a test to be positive even when you do not have chlamydia. This is called a false positive test result. Both of these false tests are very rare but can sometimes explain why you get a different result to your sexual partner.

If you are worried about your test result, talk to your doctor,


Do I have to pay for a test?

If you have a test at an  Sexual Health clinic, GUM clinic or with the National Chlamydia Screening Programme (NCSP) then your tests and any treatment is free.

If you go to your GP, the test is free but you may have to pay a prescription charge for treatment, unless you qualify for free prescriptions.

If you buy a test from a pharmacy, you will have to pay.

Find out more about:

symptoms of chlamydia

treatment for chlamydia

protecting yourself against chlamydia


Treating chlamydia 

Chlamydia is usually treated with antibiotics. Antibiotics are very effective for treating chlamydia. More than 95 out of 100 people with chlamydia will be cured if they take their antibiotics correctly.

The two most commonly prescribed antibiotics to treat chlamydia are: 

azithromycin (single dose)

doxycycline (a longer course, usually two capsules a day for a week)

Your doctor may give you different antibiotics if you have an allergy, or are pregnant. A longer course of antibiotics may be used if your doctor is concerned about complications of chlamydia. Other common antibiotics are ofloxacin and erythromycin.

If there is a high chance you have been infected with chlamydia (for example, your partner has been diagnosed with chlamydia and you have had unprotected sex with them) you might be started on treatment before you get your test results.


Pregnant or breastfeeding

Tell your doctor if you are pregnant or breastfeeding, as this will affect the type of antibiotic you can be given. Azithromycin, amoxicillin and erythromycin are all safe for pregnant women to take.


Antibiotics and contraception

Most antibiotics are safe to use with contraception. If you vomit or have severe diarrhoea they may be less effective and put you at risk of pregnancy, especially if you have unprotected sex. 

Talk to your doctor, sexual health adviser or pharmacist about whether the antibiotics you are given might affect your contraception.


Having sex again

You should not have sex for at least one week after you have finished your antibiotic treatment. You may need to avoid having sex for longer if your sexual partner has not been treated so that you do not become re-infected. You should also avoid having sex until your symptoms have gone.


Side effects of chlamydia treatment

The side effects of antibiotics are usually mild. The most common side effects include: 

stomach pain


feeling sick

vaginal thrush (vaginal yeast infection, also called candida)

Occasionally, doxycycline can cause a skin rash if you are exposed to too much sunlight (photosensitivity).


Treatment for sexual partners

If you test positive for chlamydia, it's important that your current sexual partner and any other recent sexual partners are also tested and treated.

In the UK, it's advised that you contact any sexual partners you've had within the past six months.

A specialist sexual health adviser can help you to contact all your sexual partners. Sexual health clinics or GUM clinics can contact your sexual partners for you if you prefer. Either you or the clinic can speak to them, or can send them a note (called a contact slip) to let them know that they may have been exposed to a sexually transmitted infection (STI). The note will suggest that they go for a check-up. The note will not have your name on it, and it may or may not say what the infection is. Your confidentiality will be protected.

Find out more about:

getting tested for chlamydia

complications of chlamydia

protecting yourself against chlamydia


Do I need another test to check chlamydia has gone?

If you take all your antibiotics correctly then you should not need a follow-up test. The doctor or nurse will advise you to have a repeat test if:

you were treated for chlamydia and you are pregnant

you forgot to take any of your medication or did not take it properly

you had sex before you and your partner had finished treatment

your symptoms have not gone or if they have come back


Complications of chlamydia 

If chlamydia is not treated, it can sometimes spread and cause long-term problems.

This page explains about:

complications in women

complications in men


Complications in women

In women, chlamydia can spread to the womb (uterus), ovaries or the fallopian tubes. This can cause a condition called pelvic inflammatory disease (PID). Women may also develop an inflammation of the cervix (cervicitis), or an infection in the Bartholin’s glands near the vaginal opening. Very rarely women can develop a reactive arthritis.



Chlamydia is one of the main causes of PID in women. PID is an infection of the womb (uterus), ovaries and fallopian tubes. It can cause infertility, persistent (chronic) pelvic pain and it increases the risk of miscarriage and ectopic pregnancy. PID can be treated with antibiotics, and the risk of infertility is reduced if PID is treated early. 

Inflammation of the cervix (cervicitis)

Chlamydia can cause inflammation of the cervix (the neck of the womb), known as cervicitis. Cervicitis often causes no symptoms, but if you do get symptoms these may include: 

bleeding during or after sex

bleeding between periods

discomfort in your lower abdomen

vaginal discharge

pain during sex


Blocked fallopian tubes

Chlamydia can spread to cause inflammation in the fallopian tubes (known as salpingitis). This can make it difficult for an egg to travel from the ovary to the womb and can make becoming pregnant more difficult. Find out more about conception and getting pregnant.

Even if a fallopian tube is only partially blocked, this will increase the risk of ectopic pregnancy (when a fertilised egg implants outside the womb, usually in a fallopian tube). Blocked fallopian tubes can sometimes be treated with surgery.


Swollen Bartholin’s glands (Bartholinitis)

The glands that produce a woman's lubricating mucus during sex are known as the Bartholin’s glands. They sit on either side of the vaginal opening. Chlamydia can cause the glands to become blocked and infected, leading to a Bartholin’s cyst.

The cyst is usually painless, but if it becomes infected it can lead to an abscess. An abscess is usually red, very tender, painful to touch, and can cause a fever. An infected abscess needs to be treated with antibiotics. Very occasionally an operation is needed to drain the abscess.


Complications in men



Urethritis is inflammation of the urethra (urine tube) that runs along the underside of the penis. Symptoms include: 

a white cloudy discharge from the tip of the penis

pain or a burning sensation when you urinate

the urge to urinate often

irritation and soreness around the tip of the penis

There are many causes of urethritis but chlamydia infection is the most common. If you have urethritis and the cause is not known then this is called a “non-specific urethritis” (NSU). NSU is often treated with the same antibiotics as chlamydia.



The main symptoms of epididymitis are swelling and tenderness in the epididymis. The epididymis is part of a man’s reproductive system and carries sperm from the testicles. If the testicles are affected it is called epididymo-orchitis.

A chlamydia infection in the epididymis can cause inflammation, swelling and tenderness inside the scrotum (ball sack). A few men will notice that the whole of the scrotum is red and tender. Infection can lead to a build-up of fluid in the affected area, or even an abscess. If left untreated, epididymitis can sometimes lead to infertility.


Reactive arthritis

Chlamydia can cause a reactive arthritis (inflammation of the joints). In some people the arthritis develops as part of a syndrome and they also develop inflammation of the urethra (urethritis) and the eyes (conjunctivitis).

Reactive arthritis is more likely to occur in men than women. Symptoms usually get better in 3-12 months although they can return after this. Symptoms can usually be controlled by painkillers known as non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. Some people will need to see a joint specialist if their symptoms are severe.

Find out more about:

chlamydia symptoms

protecting yourself against chlamydia

sexually transmitted infections (STIs)


Preventing chlamydia 

There are several ways to protect yourself against chlamydia and most other sexually transmitted infections (STIs), such as genital herpes and gonorrhoea.

Anyone who is sexually active can catch chlamydia, especially people who change partners frequently or don't use a barrier method of contraception, such as a condom, when having sex.

You can help to prevent the spread of chlamydia by:

using a condom every time you have vaginal or anal sex

using a condom to cover the penis during oral sex

using a dam (a piece of thin, soft plastic or latex) to cover the female genitals during oral sex or when rubbing female genitals together

not sharing sex toys

If you do share sex toys, wash them or cover them with a new condom between each person who uses them.

If you think you’re at risk of having an STI, or you have any symptoms, visit your local sexual health clinic to have them checked out. Find your local sexual health services.

You can find out more about all sexual health services, contraception and STIs on the FPA helpline 0845 122 8690 or call the Worth Talking About helpline on 0800 282930 (2pm-10pm every day) for advice on contraception, sexual health and relationships.

Find answers to some common health questions:

Are sex toys safe?

How soon do STI symptoms appear?

What services do sexual health clinics provide?