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

Chlamydia is found most frequently in people under the age of 25 years although it can infect people of all ages.

How do you catch chlamydia?

Chlamydia is passed on:

  • through unprotected sex (using no condom) whether vaginal, oral or anal sex (or sharing sex toys) with someone who has chlamydia
  • from an infected mother to her baby during childbirth (vaginal delivery)
  • sometimes from genitals to fingers to eyes, causing painful, red eyes (conjunctivitis)

Chlamydia cannot be caught by kissing, hugging, sharing baths or towels, using swimming pools or from toilet seats.

What symptoms would I notice if I had chlamydia?

Most women do not notice anything wrong. Some women may notice one or more of the following: • bleeding between periods or after sex

  • pain in the lower abdomen, particularly during sex
  • burning pain when passing urine
  • a change in the colour or amount of vaginal discharge

Most men do not notice anything wrong. Some men may notice one or more of the following:

  • a discharge from the tip of the penis
  • a burning feeling or pain when passing urine

If you think you're at risk of having a sexually transmitted infection (STI) or have any symptoms of chlamydia, contact your GP or a sexual health clinic for advice.

Is chlamydia serious?

Although chlamydia does not usually cause any symptoms and can normally be treated with a short course of antibiotics, it can be serious if it's not treated early on.

Prompt treatment is recommended to prevent more serious problems:

In women: the spread of infection to the womb and ovarian tubes may cause infertility

In men: the spread of infection to the testicles causing pain and swelling

Getting tested for chlamydia

If you’re sexually active, it’s a good idea to get tested for chlamydia every year, even if you feel fine.

It’s good practice to go for testing if you’re about to start a new relationship, and for your partner to do the same

Women If you do not have symptoms no internal examination is needed and a swab is taken from inside the vagina.

If you have had anal sex or given your partner oral sex, you may be advised to have swabs taken from the rectum (back passage) and/or throat.

Men If you do not have any symptoms you will usually be asked to give a urine sample. However, if you do have symptoms, such as a discharge from the penis, a doctor or nurse will take a swab from the tip of your penis. After this, you will be asked to give a urine sample.

Men who have sex with men may be advised to have swabs taken from the rectum and/or throat.

Anyone can get a free and confidential chlamydia test at a sexual health clinic, or a GP surgery or you can order online. You can also buy chlamydia testing kits to do at home, if you choose to do this make sure that the kit has a CE quality assurance mark. This means that, provided you use it correctly, the kit will work properly and is safe.

Find your nearest GUM clinic here.

How soon after possible infection can I have a chlamydia test?

It is possible that if you test for chlamydia soon after being infected, your test may not find the infection. For this reason you may be advised to repeat the chlamydia test two weeks after the time when you were at risk of catching it.

How is chlamydia treated?

Chlamydia can be easily treated with antibiotics. All treatments for STIs, including chlamydia, are free. If you test positive for chlamydia, you will be told where you can get your treatment.

Important information about your treatment The antibiotics are highly effective if taken correctly. The antibiotics don’t stop contraceptive pills, implants, patches or injections from working.

What about my partner? As chlamydia is sexually transmitted, it is important that your partner is tested for this as well as other STIs. This is known as partner notification. If you wish and with your permission, the clinic can contact your partner for you without mentioning your name. Some of your previous partners may also need testing – you will be advised about this.

What happens if chlamydia is left untreated?

Women Chlamydia may spread from the neck of the womb (cervix) to the womb (uterus) the ovarian (or Fallopian) tubes and ovaries. This is called pelvic inflammatory disease, or PID. PID increases the risk of infertility and/or ectopic pregnancy (a pregnancy that occurs outside the womb, usually in one of the ovarian tubes).

Men Chlamydia can spread from the urethra to the testicles causing pain and/ or swelling of the testicles.

Women and men In rare cases chlamydia may cause pain and swelling in joints such as the ankles or knees. This is known as sexually acquired reactive arthropathy (SAR A) and is more common in men. Sometimes inflammation of the eyes (conjunctivitis) also occurs.

How long should I wait after treatment before I can have sex again? To ensure that the chlamydia infection is cured, patients and their treated partners are advised not to have sex for a week. This includes oral sex and sex with condoms. Patients treated with a seven day course of doxycycline should wait until they have finished taking all their antibiotics. Patients treated with a single dose of azithromycin should wait until one week after taking it.

Can I catch chlamydia again? Yes you can. To prevent this make sure your partners have been treated. Protect yourself with new partners by using a condom for all vaginal, anal and oral sex. Or Ensure that both you and a new partner have a sexual health screen before having sex without a condom.

Do I need to get tested for chlamydia again?

If you are under 25 years of age you should take another chlamydia test

  • three months after being treated for chlamydia,


  • once a year, or
  • if you have a new sexual partner

Anyone who has symptoms which might be caused by chlamydia should take a test. Anyone who has had sex without condoms with a new partner should be tested. All pregnant women treated for chlamydia should re-test after treatment

Preventing chlamydia

You can reduce the risk of all infections by:

  • Using condoms for all types of penetrative sex (vaginal, anal sex especially; you may also want to consider condoms or a dam for oral sex)
  • Having non penetrative sex (such as body rubbing and mutual masturbation)
  • Being tested for STIs before having sex with someone new, and advising that they also get tested.
  • Reducing the number of partners you have sex with.
  • Planning on how you will protect yourself and your sexual partners from infections when under the influence of alcohol or other recreational drugs.
  • 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.


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

If you do get symptoms, these usually appear between 1 and 3 weeks after having unprotected sex with an infected person. For some people they don't develop until many months later.

Sometimes the symptoms can disappear after a few days. Even if the symptoms disappear you may still have the infection and be able to pass it on.

Symptoms in women

At least 70% of women with chlamydia don't notice any symptoms. If they do get symptoms, the most common include: 

  • pain when urinating
  • unusual vaginal discharge
  • pain in the tummy or pelvis
  • pain during sex
  • bleeding after sex
  • bleeding between periods

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

Symptoms in men

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

  • pain when urinating
  • white, cloudy or watery discharge from the tip of the penis 
  • burning or itching in the urethra (the tube that carries urine out of the body)
  • pain in the testicles

If chlamydia is left untreated, the infection can cause swelling in the epididymis (the tubes that carry sperm from the testicles) and the testicles. This could affect your fertility.

Chlamydia in the rectum, throat or eyes

Chlamydia can also infect:

  • the rectum (back passage) if you have unprotected anal sex – this can cause discomfort and discharge from your rectum
  • the throat if you have unprotected oral sex – this is uncommon and usually causes no symptoms
  • the eyes if they come into contact with infected semen or vaginal fluid – this can cause eye redness, pain and discharge (conjunctivitis)

When to seek medical advice

If you have any symptoms of chlamydia, visit your GP, community contraceptive service or local sexual health clinic as soon as possible.

Find a sexual health services near you.

You should also get tested if you don't have any symptoms but are concerned you could have a sexually transmitted infection (STI).

If you're sexually active and under 25 years old, you should get tested for chlamydia every year or every time you have a new partner.


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 recommended tests for chlamydia are simple, painless and generally very reliable.

They involve sending a sample of cells to a laboratory for analysis. You don't necessarily have to be examined by a doctor or nurse first and can often collect the sample yourself.

There are two main ways the sample can be collected:

  • using a swab – a small cotton bud is gently wiped over the area that might be infected, such as inside the vagina or inside the anus
  • urinating into a container – this should ideally be done at least 1 or 2 hours after you last urinated

Men will usually be asked to provide a urine sample, while women will usually be asked to either swab inside their vagina or provide a urine sample.

The results will normally be available in 7 to 10 days. If there's a high chance you have chlamydia – for example, you have symptoms of the infection or your partner has been diagnosed with it and you've had unprotected sex with them – you might start treatment before you get your results.

When should I get tested?

Don't delay getting tested if you think you might have chlamydia. Being diagnosed and treated as soon as possible will reduce your risk of developing any serious complications of chlamydia.

You can get a chlamydia test at any time – although you might be advised to repeat the test later on if you have it less than 2 weeks since you had sex because the infection might not always be found in the early stages.

You should consider getting tested for chlamydia if:

  • you or your partner have any symptoms of chlamydia
  • you've had unprotected sex with a new partner
  • a condom splits while you're having sex
  • you or your partner have had unprotected sex with other people
  • you think you could have a sexually transmitted infection (STI)
  • a sexual partner tells you they have an STI
  • you're pregnant or planning a pregnancy

If you're under 25 years of age and sexually active, getting tested every year or when you change sexual partner is recommended because you're more likely to catch chlamydia.

If you have chlamydia, you may be offered another test around 3 months after being treated. This is because young adults who test positive for chlamydia are at increased risk of catching it again.

Where can I get a chlamydia test?

You can get a free, confidential chlamydia test at:

  • a sexual health clinic
  • a genitourinary medicine (GUM) clinic
  • your GP surgery
  • most contraceptive clinics

You can go to whichever place is the most comfortable and convenient for you. Search for your nearest sexual health service.

You can also buy chlamydia testing kits to do at home, but these aren't always very accurate. If you're considering using one of these tests, speak to your pharmacist or GP for advice.

You can also buy chlamydia testing kits to do at home.

Young people under 25 years of age can get tested as part of the National Chlamydia Screening Programme (NCSP). This is often in places such as pharmacies, colleges and youth centres.


Chlamydia can usually be effectively treated with antibiotics. More than 95% of people will be cured if they take their antibiotics correctly.

You may be started on antibiotics once test results have confirmed you have chlamydia. But if it's very likely you have the infection, you might be started on treatment before you get your results.

The two most commonly prescribed antibiotics for chlamydia are: 

  • azithromycin – given as 2 or 4 tablets at once
  • doxycycline – given as 2 capsules a day for a week

Your doctor may give you different antibiotics, such as amoxicillin or erythromycin, if you have an allergy or are pregnant or breastfeeding. A longer course of antibiotics may be used if your doctor is concerned about complications of chlamydia.

Some people experience side effects during treatment, but these are usually mild. The most common side effects include tummy pain, diarrhoea, feeling sick, and vaginal thrush in women.

When can I have sex again?

If you take your antibiotics correctly, you may not need to return to the clinic.

However, you will be advised to go back for another chlamydia test if:

  • you had sex before you and your partner finished treatment
  • you forgot to take your medication or didn't take it properly
  • your symptoms don't go away
  • you're pregnant

If you're under 25 years of age, you should be offered a repeat test for chlamydia 3 months after finishing your treatment because you're at a higher risk of catching it again.

Testing and treating sexual partners

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

A specialist sexual health adviser can help you contact your recent sexual partners, or the clinic can contact them for you if you prefer.

Either you or someone from the clinic can speak to them, or the clinic can send them a note to let them know they may have been exposed to a sexually transmitted infection (STI).

The note will suggest that they go for a check-up. It will not have your name on it, so your confidentiality will be protected.


If chlamydia isn't treated, it can sometimes spread and cause potentially serious problems.

Complications in men

Inflammation of the testicles

In men, chlamydia can spread to the testicles and epididymis (tubes that carry sperm from the testicles), causing them to become painful and swollen. This is known as epididymitis or epididymo-orchitis. This is very rare.

The inflammation is usually treated with antibiotics. If it's not treated, there's a possibility it could affect your fertility.

Reactive arthritis

Chlamydia is the most common cause of sexually acquired reactive arthritis (SARA). This is where your joints, eyes or urethra (the tube that passes urine out of the body) become inflamed, usually within the first few weeks after having chlamydia.

It can affect women who have had chlamydia but is more common in men.

There's currently no cure for SARA, but most people get better in a few months. In the meantime, treatment with non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can help relieve the symptoms.

Complications in women

Pelvic inflammatory disease (PID)

In women, chlamydia can spread to the womb, ovaries or fallopian tubes. This can cause a condition called pelvic inflammatory disease (PID).

PID can cause a number of serious problems, such as:

  • difficulty getting pregnant or infertility
  • persistent (chronic) pelvic pain
  • an increased risk of ectopic pregnancy (where a fertilised egg implants itself outside the womb)

The symptoms of PID are generally similar to the symptoms of chlamydia, including discomfort or pain during sex, pain during urination, and bleeding between periods and after sex.

PID is usually treated with a 2-week course of antibiotics. The risk of experiencing problems such as infertility is lower if it's treated early, so it's important to seek medical advice as soon as possible if you have symptoms of the condition.

Pregnancy complications

If you have chlamydia that's not treated while you're pregnant, there's a chance you could pass the infection on to your baby. If this happens, your baby may develop an eye infection (conjunctivitis) and lung infection (pneumonia).

If your baby has symptoms of these conditions, your midwife or GP can arrange for a test to check for chlamydia, and antibiotics can be used to treat the infection.

Untreated chlamydia in pregnancy may also increase the risk of problems such as your baby being born prematurely (before 37 weeks of pregnancy) or with a low birthweight.

The information on this page has been adapted by NHS Wales from original content supplied by NHS UK NHS website
Last Updated: 06/04/2022 15:14:02