Description, causes, prevention, treatment and medicines

Chlamydia is a sexually transmitted infection caused by the bacterium Chlamydia trachomatis. It affects both men and women, and it’s spread by having sex with a person who has the infection.

Chlamydia is the most commonly reported sexually transmitted infection in Australia, and is most commonly reported in adults younger than 30 years of age. The good news is that it is treatable with antibiotics.

Symptoms of chlamydia infection

A big problem with chlamydia is that it often produces no symptoms, and if left undetected and untreated, complications can occur. People who have chlamydia can still transmit the infection, even if they don’t have any symptoms themselves.

When symptoms do occur, they usually become noticeable several weeks after having sex with an infected person.

Symptoms in women

Women with chlamydia might notice:

  • an unusual vaginal discharge;
  • vaginal bleeding between periods;
  • bleeding or pain during or after sex;
  • pain, burning or discomfort when urinating;
  • urinating more frequently than usual; or
  • cramping or pain in the pelvis or lower abdomen.

There are often no symptoms at all in women.

Symptoms in men

Men with chlamydia may experience:

  • pain, burning or discomfort when urinating;
  • discharge from the urethra (the tube through which urination occurs), which can be watery or mucus-like; and
  • swollen and sore testicle(s) (usually only one testicle is affected).

Most men with chlamydia do not experience any symptoms.

Other symptoms

Chlamydial infection of the rectum (called proctitis) is possible through having anal sex with someone who has the infection. Infection can also sometimes spread from the cervix and vagina to the rectum. Symptoms of proctitis include pain, a discharge of pus or mucus and/or bleeding from the rectum.

Having oral sex with someone who has chlamydia can result in infection of the throat. Usually there are no symptoms with throat infection.

If infected genital fluid comes into contact with your eyes, it is possible to get conjunctivitis (inflammation of the thin tissue that lines the inner eyelids and covers the whites of the eyes).


Women with untreated chlamydia are at risk of complications such as:

  • pelvic inflammatory disease (PID), in which the reproductive organs in the pelvis become inflamed;
  • chronic pelvic pain;
  • ectopic pregnancy (in which a pregnancy develops outside the uterus, such as in the fallopian tubes); and
  • infertility or difficulty getting pregnant, due to infection and scarring of the fallopian tubes.

Pregnant women who are infected can pass the infection to their baby during birth, which could result in the baby developing conjunctivitis and/or pneumonia. Chlamydia infection in pregnancy can also be associated with premature labour.

A type of joint inflammation called reactive arthritis is another possible complication of chlamydia infection.

People with reactive arthritis experience painful, swollen joints several weeks after infection. Often the knees and ankles are involved, and a skin rash and eye inflammation may also be seen.

Reactive arthritis usually gets better on its own with time.

How do you get chlamydia?

Chlamydia is sexually transmitted – you can catch chlamydia by having sex with someone who already has chlamydia. Chlamydia is passed from person to person through sexual contact with the penis, vagina, mouth or anus, or through contact with infected genital fluids (vaginal fluid or semen). You cannot catch chlamydia from public toilets, public pools or general contact with other people.

It’s important to note that it is possible to catch chlamydia more than once – previous infection does not mean that you are immune to the disease.

How do I know if I have chlamydia?

See your doctor (GP) or visit a sexual health clinic if you are concerned that you might have chlamydia, even if you don’t have any symptoms.

To diagnose chlamydia, your doctor will ask about any symptoms and may perform a physical examination (physical examination is not always necessary). There are simple tests that can be done to determine whether you have chlamydia, and a check for other STIs can be done at the same time, if needed.

Chlamydia tests

It is possible to diagnose chlamydia by performing a test called a nucleic acid amplification test (NAAT) on a urine sample.

Vaginal or cervical swabs can also be taken for testing in women. A swab test involves taking a specimen from a site such as the vagina or cervix. A vaginal swab can be collected by your doctor, or (if you prefer) you can swab yourself (your doctor can instruct you on what to do).

Sometimes swabs from the anus (which can be self-collected) or throat are recommended.

Urine samples and/or swabs are sent to a laboratory for testing.

Who should be tested for chlamydia?

You should be tested for chlamydia and STIs if:

  • you have symptoms;
  • you know that a recent sex partner has been diagnosed with chlamydia or another STI;
  • you have had unprotected sex; or
  • you are sexually active and you would like to be tested for STIs.

Antibiotic treatment for chlamydia

If your doctor does detect chlamydia, don’t worry: the infection can be treated effectively with antibiotics.

Antibiotics may be given as:

  • a single dose of azithromycin; or
  • a 7-day course of doxycycline.

Women with pelvic inflammatory disease and people with other complications caused by chlamydia infection will need a longer course of antibiotics. Antibiotics can cure the infection. However, antibiotics are not effective in reversing complications related to scarring of the reproductive organs in cases where infection has gone undetected.

To prevent the spread of infection, you should not have sexual activity with other people for a week after a single dose of antibiotics, or until a 7-day course of antibiotics has been completed. Your doctor may suggest testing for chlamydia several months after treatment to ensure that it has been successfully treated.

Screening for other STIs

As chlamydia is transmitted through unprotected sex, your doctor may suggest you be screened for other sexually transmitted diseases and if necessary, you and your partner(s) treated.

Telling your partner(s) that they should be tested for chlamydia
It’s important that you inform any current and recent sexual partners you may have had that they might be at risk of chlamydia. Any partners from the last 6 months should be contacted.

Remember, they might not display any symptoms but if they are not informed about their risk of chlamydia, they could develop serious conditions such as pelvic inflammatory disease, as well as continue to spread the infection to others, including re-infecting you if they are a current sex partner.

Your doctor or sexual health clinic can help you contact partners. If you wish, they can help contact partners anonymously to let them know that they should be tested without them knowing that you are involved.

There are also online resources available that suggest how to contact people. Some also provide anonymous contact tracing, where the person will be contacted but your name will not be mentioned.

Screening for chlamydia

Screening involves testing for a condition when there are no symptoms, so that the condition can be treated before it becomes serious or complications develop. Screening for chlamydia has been shown to reduce complications in women.

In Australia, chlamydia screening is recommended for pregnant women aged younger than 25 years. Screening for sexually active people aged 15-29 years is also recommended.

Preventing infection with chlamydia

You can help prevent being infected with chlamydia (and other sexually transmitted infections) by always using a barrier method of contraception, such as a condom when you have sex, particularly if you have a new sexual partner.

Remember, many people with chlamydia don’t know they have it and could infect someone else unknowingly.

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