Chlamydia is a sexually transmitted infection (STI) caused by the bacterium chlamydia trachomatis. In the UK, the number of new diagnoses has been steadily increasing each year since the mid-1990s, and it has now become the most commonly diagnosed STI.


Sexually active women aged under-25, have a 1 in 10 chance of getting chlamydia, and men who are aged between 20 and 30 are most at risk of becoming infected.


As chlamydia sometimes has no symptoms, in both men and women, it can often go undiagnosed, unless it leads to complications. However, once the infection has been diagnosed, it is treatable.





In women, genital chlamydia does not often cause any symptoms. However, some women may have ‘non-specific symptoms’ such as:


Cystitis, a change in their vaginal discharge, and mild lower abdominal pain. If you visit your GP, or family planning doctor with any of these symptoms, you can ask to have a chlamydia test taken, even if you are not offered one.


If left untreated, the chlamydia infection may lead to the following symptoms:


Pelvic pain, pain during sexual intercourse, or occasionally, bleeding between periods.The chlamydial infection can also spread to the womb, and cause Pelvic Inflammatory Disease (PID). PID is a major cause of infertility, ectopic pregnancy and miscarriage.




A man with chlamydia commonly experiences a urethral discharge from the penis. You may also have inflammation of the tube leading from the bladder to the tip of the penis (urethritis), and inflammation of the tube leading from the testes to the penis (epididymitis).


You may also experience mild irritation at the end of your penis that will usually disappear after two or three days. However, after the discomfort disappears, you may still have the chlamydia infection. This means that you can pass it on to a sexual partner. You also risk the complication of inflamed and swollen testicles.


In rare cases, chlamydia can also cause an uncommon condition that affects the eyes and joints, known as Reiters syndrome. Chlamydia can also cause fertility problems in men, approximately half of all men with symptoms have impaired fertility, such as epididymitis.




As chlamydia is a sexually transmitted infection (STI), it is transmitted (passed on) from one person to another during intimate sexual contact. You can catch chlamydia through:


  • Having unprotected vaginal sex
  • Having unprotected anal sex
  • Having unprotected oral sex
  • Having genital contact with an infected partner
  • As it is common for someone with the chlamydia infection not to have symptoms, it is possible for him or her to infect a partner without knowing.


You cannot catch chlamydia by using the same toilet seat as someone who is infected, and it cannot be transmitted through swimming pools or saunas.


Chlamydia can be passed from a mother to her baby during childbirth. Although no obvious symptoms are immediately apparent, the infection will often develop two weeks after birth, and can result in complications such as pneumonia.





Up until five years ago, women were tested for chlamydia by taking a swab from the cervix (neck of the womb) using an instrument called a speculum (similar to a spatula).


However, in recent years newer tests have been developed that allow a woman to carry out a simple procedure at home, using either a urine sample, or by taking a swab from the lower vagina. The sample is put into a container and sent to a laboratory to be tested. The need to have an intimate and embarrassing examination is therefore avoided.




For men, in the past, the test for chlamydia involved putting a swab into the opening of the urethra at the tip of the penis. However, a urine test is now commonly used, and although it is slightly less reliable than using a swab, it is a much easier and less painful procedure.


Tests for sexually transmitted infections (STIs) are usually carried out at STI clinics (also known as genito-urinary medicine or GUM clinics). They have special testing facilities, and can also sometimes provide you with assistance in contacting, testing, and treating your previous sexual partners. You can find details of your nearest sexual health clinic in the phone book, or by searching at this link for your nearest GUM clinic. You can attend these clinics at any age, even if you are less than 16 years of age (the age of consent for sex), and all results are treated confidentially.





After being diagnosed with chlamydia, the uncomplicated infection can usually be successfully treated using antibiotics, commonly, azithromycin and doxycycline. Research has shown that 80-90% of people with chlamydia are cured after taking one of these antibiotics.


Azithromycin is taken as a single dose, and doxycycline is taken twice a day for seven days. You should consult your GP who will be able to provide you with advice about which antibiotic is the most suitable for you. For example, if you are pregnant, some antibiotics may not be suitable, but alternative antibiotics are available. Again, you should consult your GP.


The most common side effects of antibiotics include:


  • Stomach upsets
  • Stomach pain
  • Diarrhoea
  • Feeling Sick


However, the side effects of antibiotics are usually mild. Occasionally, if you take doxycycline, you may get a skin rash if you are exposed to sunlight (photosensitivity).


Sexual Partners


Chlamydia can be easily passed on through intimate sexual contact. Therefore, if you have the infection, anyone who you have recently had sex with (in the last six months) may also have it. It is therefore vital that your partner is tested, regardless of whether they have any symptoms or not.


Any of your previous sexual partners will also need to be tested. Your local GUM clinic may be able to help by notifying any of your previous partners on your behalf. If you or your current partner is diagnosed with chlamydia, you should not have sex until you have both finished your course of the treatment.


Treatment during pregnancy


The treatment of pregnant women with chlamydia is an area that is not fully understood. It is not certain whether some of the medicines that are usually used to treat the condition affect the unborn baby. However, if you are pregnant you should not take doxycycline or tetracycline because there is a risk that they can harm the development of the babys teeth and bones. However, alternative medicines are available, and you should discuss these with your GP.


This has been adapted from ‘Sexual Health Birmingham’ the authors are Dr S Acharya & Dr J Arumainayagam.

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