What you need to know about chlamydia 

Chlamydia is the most common sexually transmitted infection (STI) in the UK and affects both sexes. One of the reasons for its prevalence is that it often causes no symptoms. However, if left untreated, it can have serious consequences for your fertility and cause permanent damage to your reproductive organs. 

What causes chlamydia? 

Chlamydia is caused by infection with bacteria called Chlamydia trachomatis. It is spread through unprotected sex — including oral, anal and vaginal sex — or contact with infected genitals, semen or vaginal fluid, as well as through sharing sex toys that aren’t washed or covered with a new condom before use. 

Depending on how you become infected with chlamydia, you may develop symptoms in your genitals, throat, anus or eyes. 

Myths about how you get chlamydia

It is important to note that you can’t be infected with chlamydia through casual contact. This includes sitting on a toilet seat, sharing clothes or kitchen utensils, hugging, kissing or swimming in the same water as an infected person. 

This is because your skin acts as a barrier to chlamydia and chlamydia doesn’t survive for long outside the human body (eg on a toilet seat). 

Risk factors for chlamydia

As chlamydia is an STI, the main risk factor is unprotected sex. 

Your risk is higher if you have multiple sexual partners, are having sex with a partner who is having sex with multiple partners, or have had chlamydia before. 

Chlamydia symptoms

Most people infected with chlamydia do not develop any symptoms. 

If you do develop symptoms, they will most likely occur one to three weeks after you were infected; less commonly, you may develop symptoms several months later. 

If your symptoms go away after several days, this does not necessarily mean the infection has cleared — you should, therefore, still get tested and seek treatment. 

If you have genital chlamydia affecting your vagina, symptoms include a burning sensation and/or pain when urinating, bleeding in between your periods, bleeding after sex and pain during sex. 

If you have genital chlamydia affecting your penis, symptoms include a burning sensation and/or pain when urinating, pain in your lower abdomen, pain in your testicles, and unusual discharge from your penis — this discharge may be cloudy, watery, white, yellow or green. 

Chlamydia in the eye

Chlamydia can infect your eyes if infected semen or vaginal fluid makes contact with your eyes. This may occur, for example, if your hands make contact with the genitals of someone who is infected and you then rub your eyes with your hands. 

Symptoms of chlamydia in the eyes are similar to conjunctivitis ie redness and pain in your eyes and unusual discharge from your eyes. 

Chlamydia in the throat

Unprotected oral sex can lead to infection of the throat with chlamydia. In the vast majority of cases, chlamydia in the throat doesn’t cause any symptoms. 

However, in rare instances where symptoms occur, they include a sore throat, redness inside your throat, mouth sores and white spots at the back of your mouth.

Chlamydia in the anus

Unprotected anal sex can lead to infection of the anus and rectum (back passage) with chlamydia. This can cause anal pain and pain in your back passage, as well as anal bleeding and a mucus-like discharge from your anus.

When should you get tested for chlamydia? 

As chlamydia doesn’t usually have any symptoms, it is important to have regular sexual health testing. 

If you're aged under 25, sexually active and have a vagina, it is recommended that you have sexual health testing, including a test for chlamydia, once a year and whenever you have sex with a new or casual partner. 

If you're aged under 25, sexually active and have a penis, it is recommended that you have sexual health testing, including a test for chlamydia, once a year if you’re having unprotected sex with a new or casual partner.

If you develop any of the symptoms of chlamydia mentioned above, find out that someone you have had sex with has chlamydia, or the condom or dental dam splits while you’re having sex, you should also get tested for chlamydia. 

Diagnosing chlamydia

To find out if you have chlamydia, you don’t usually need to be physically examined. Instead, some of your cells will need to be collected so they can be tested in a lab for the presence of chlamydia bacteria.

There are two ways to test for chlamydia: a urine test and a swab test. 

For a urine test, you will need to provide a fresh urine sample. This involves urinating into a container — you should leave at least one hour between when you last urinated and collecting your urine sample for the lab. 

For a swab test, a cotton bud will be used to wipe the area that you think is infected in order to gather some cells. For example, this may involve wiping the area inside your vagina or anus.

If your doctor or nurse suspects that you are very likely to have chlamydia, for example, if you have obvious symptoms or know you have had sex with an infected individual, they may recommend starting treatment for chlamydia before you receive your test results.  

If you test positive for chlamydia, you will need to inform your current sexual partner(s) and any sexual partners you have had in the last six months. 

Treating chlamydia

Chlamydia will not go away on its own. But it can be effectively treated with a course of antibiotics. 

You will most likely be prescribed either doxycycline or azithromycin. You will need to complete your course of antibiotics as instructed to ensure your infection is properly cleared — this includes finishing your course of antibiotics even if your symptoms go away. 

Alternative antibiotics are available if you’re allergic to doxycycline or azithromycin or can’t take them because you’re pregnant or breastfeeding.  

You should not have sex of any kind while being treated for chlamydia and, in some cases, for a short time after treatment. 

When can you have sex again? 

You should always follow the advice of your doctor but, in general, if you’re prescribed doxycycline, you and your partner must complete the full course before having sex again. 

If you’re prescribed azithromycin, you and your partner should wait seven days after completing the full course before having sex again. 

This applies to all types of sex: vaginal, oral and anal. 

Do you need a check-up after having chlamydia?

If you have tested positive for chlamydia and are aged under 25, it is recommended that you get tested again three to six months later. This is because those aged under 25 who have been infected with chlamydia are more likely to be infected again. 

Complications of untreated chlamydia

If chlamydia is left untreated, it can cause permanent damage to your reproductive organs, reduce your fertility and lead to other health conditions, such as sexually acquired reactive arthritis (SARA).

SARA causes inflammation of your joints, eyes and/or urethra (the tube through which urine exits your body). The most common cause of SARA is chlamydia and it usually lasts several months before it gets better on its own.  

Complications of untreated vaginal chlamydia

Chlamydia can cause pelvic inflammatory disease (PID) when it spreads from the vagina to the womb, ovaries and/or fallopian tubes. This can lead to ongoing symptoms of pain during sex and when urinating, and bleeding after sex and in between periods. It can also cause persistent pelvic pain and reduce your fertility by damaging your womb, ovaries and/or fallopian tubes. 

If you are pregnant and have chlamydia, it increases the risk of premature labour and your baby having a low birth weight; the latter is linked to poor health outcomes for your child in the future. The infection can also infect your baby, causing conjunctivitis if it infects their eyes and/or pneumonia if it infects their lungs. 

Complications of untreated penile chlamydia

Chlamydia can cause epididymitis when it spreads from the penis to the testicles and the tubes that carry sperm from the testicles (epididymis). This causes painful swelling of your testicles. While it is a rare complication of penile chlamydia, it can reduce your fertility by reducing the quality of your sperm. 

How to prevent infection with chlamydia

The most effective way to reduce your risk of chlamydia is to consistently use barrier protection when having sex. Depending on the type of sex you're engaging in, this may involve using a condom or a dental dam (a thin film of latex or polyurethane that is placed over the vagina or anus). 

If you use sex toys, make sure they are covered with a new condom and/or are washed in warm, soapy water every time you use them.

As having multiple sexual partners increases your risk of infection, limiting the number of sexual partners you have at any one time will reduce your risk. 

You should also get tested regularly to reduce your risk of spreading chlamydia if you do become infected.