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A guide to – Chlamydia
Chlamydia – the basics 
Chlamydia is a curable sexually transmitted infection (STI) caused by a bacterium (a kind of germ) called Chlamydia trachomatis. Chlamydia can infect the urethra (water passage), the uterus (womb), the cervix (neck of womb), the ovarian (Fallopian) tubes, testicles, rectum (back passage), throat and eyes. Most men and women infected with chlamydia will not notice anything wrong.

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

Testing is available at all specialised sexual health or genitourinary medicine clinics, many family planning clinics and some family doctor (general practitioner or GP) services. Some chemists (pharmacies) offer testing. In some areas, self-testing kits can be ordered on-line. These are used to test urine or swab samples.

If you have chlamydia we recommend that you should have tests for other STIs including gonorrhoea, syphilis and HIV. 

How common is chlamydia? 
Chlamydia is the most common bacterial STI in the UK. In 2014 over 206,000 cases of chlamydia were diagnosed in England alone. 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 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

How do I get tested for chlamydia? 
If you do not have symptoms no internal examination is needed and a swab is taken from inside the vagina. This swab can be taken by the doctor, by a nurse or by you if you prefer. 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. If you do have symptoms, such as an abnormal vaginal discharge, a swab will be taken by a doctor or nurse during an internal vaginal examination.

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.

The result of your chlamydia test is not usually available on the day you visit the clinic. You will be told how you will get your results before you leave the clinic. 

How soon after possible infection can I have a chlamydia test?
We advise patients to have a chlamydia test at their first visit to a sexual health clinic, especially if they have noticed symptoms like a vaginal discharge or pain while passing water. 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? 
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).

Chlamydia can spread from the urethra to the testicles causing pain and/or swelling of the testicles. This is known as epididymo-orchitis (see the BASHH leaflet ‘Epididymo-orchitis’). 

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 (SARA) 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. 


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, then –
•	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 (see below).

Chlamydia in pregnancy 
Chlamydia can be caught by pregnant women and it is important that it is treated to prevent the baby catching the infection during childbirth. In newborn babies chlamydia may cause redness of the eyes (conjunctivitis) or inflammation of the lungs (pneumonia). Treatment of pregnant women makes sure that baby does not catch the infection. Your doctor or nurse will make sure that the antibiotic you take does not harm the baby.

We recommend that pregnant women are re-tested at least four weeks after finishing their chlamydia treatment. This is to make sure that they have a negative chlamydia test before they give birth and the baby is not at risk of infection.

This leaflet was produced by the Clinical Effectiveness Group of the British Association for Sexual Health and HIV (BASHH). The information in the leaflet is based on the ‘UK National Guideline for the management of genital infection with Chlamydia trachomatis,’ published by BASHH in 2015.

More information : BASHH :
NHS Choices :
National chlamydia screening programme :

If you would like to comment on this leaflet, please email us at : [email protected] and enter 
‘Chlamydia PIL’ in the subject box

Published October 2016, copyright BASHH. The revision date for this leaflet is October 2019