Chlamydia is 1 of the most common sexually transmitted infections (STIs) in the UK.

It's passed on through unprotected sex (sex without a condom) and is particularly common in sexually active teenagers and young adults.

If you live in England, are under 25 and are sexually active, it's recommended that you get tested for chlamydia every year or when you change sexual partner.

Symptoms of chlamydia

Most people with chlamydia do not notice any symptoms and do not know they have it.

If you do develop symptoms, you may experience:

• pain when peeing
• unusual discharge from the vagina, penis or bottom
• in women, pain in the tummy, bleeding after sex and bleeding between periods
• in men, pain and swelling in the testicles

If you think you're at risk of having a sexually transmitted infection (STI) or have any symptoms of chlamydia, visit a GP, community contraceptive service or local genitourinary medicine (GUM) clinic to get tested.

How do you get chlamydia?

Chlamydia is a bacterial infection. The bacteria are usually spread through sex or contact with infected genital fluids (semen or vaginal fluid).

You can get chlamydia through:

• unprotected vaginal, anal or oral sex
• sharing sex toys that are not washed or covered with a new condom each time they're used
• your genitals coming into contact with your partner's genitals – this means you can get chlamydia from someone even if there's no penetration, orgasm or ejaculation
• infected semen or vaginal fluid getting into your eye

It can also be passed by a pregnant woman to her baby.

Find out more about the complications of chlamydia

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

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.

If left untreated, the infection can spread to other parts of your body and lead to long-term health problems, such as pelvic inflammatory disease (PID), epididymo-orchitis (inflammation of the testicles) and infertility.

It can also sometimes cause reactive arthritis.

This is why it's important to get tested and treated as soon as possible if you think you might have chlamydia.

Find out more about the complications of chlamydia

Getting tested for chlamydia

Testing for chlamydia is done with a urine test or a swab test.

You do not always need a physical examination by a nurse or doctor.

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

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.

If you live in England, you're under 25 and you're sexually active, you should get tested for chlamydia every year or when you change sexual partner, as you're more likely to catch it.

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

Find out more about getting a chlamydia test

How chlamydia is treated

Chlamydia can usually be treated easily with antibiotics.

You may be given some tablets to take all on 1 day, or a longer course of capsules to take for a week.

You should not have sex until you and your current sexual partner have finished treatment.

If you had the 1-day course of treatment, you should avoid having sex for a week afterwards.

It's important that your current sexual partner and any other recent sexual partners you have had are also tested and treated to help stop the spread of the infection.

Under-25s who have chlamydia should 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.

Sexual health or genitourinary medicine (GUM) clinics can help you contact your sexual partners.

Either you or the clinic can speak to them, or they can be sent a note advising them to get tested.

The note will not have your name on it, so your confidentiality will be protected.

Preventing chlamydia

Anyone who's sexually active can catch chlamydia.

You're most at risk if you have a new sexual partner or do not 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.

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.

Read more about the complications of chlamydia.

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.

Read more about the complications of chlamydia.

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 genitourinary medicine (GUM) clinic as soon as possible.

Find a sexual health clinic.

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. You can get tested 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?

You shouldn't have sex – including vaginal, oral or anal sex, even with a condom – until both you and your partner(s) have completed treatment.

If you had the 1-day course of azithromycin, you should avoid having sex for a week after treatment.

This will help ensure you don't pass on the infection or catch it again straight away.

Will I need to go back to the clinic?

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.