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Chlamydia

8-minute read

Key facts

  • Chlamydia is a sexually transmitted infection (STI) that usually spreads through unprotected sex.
  • Most people with chlamydia don’t have symptoms, which means you may not know if you or your partner has it.
  • If untreated, chlamydia can cause serious complications such as infertility and chronic pain.
  • Once diagnosed, chlamydia is easy to treat with antibiotics.
  • If you’re under 30 and sexually active you are at greatest risk — you should get checked for chlamydia and other STIs regularly.


What is chlamydia?

Chlamydia is a sexually transmitted infection (STI) — a disease you can get from having unprotected sex. It’s caused by a type of bacteria called Chlamydia trachomatis.

Chlamydia is very common: it’s the most frequently reported infectious disease in Australia, and nearly 97,000 men and women are diagnosed with it each year. If you’re sexually active and under 30 years of age, you are at the highest risk of contracting chlamydia.

What are the symptoms of chlamydia?

Most people who have chlamydia show no symptoms at all. This means you won’t be able to tell if you or your partner has it. If you do get symptoms, they tend to appear 7 to 14 days after you have unprotected sex.

For women, symptoms of chlamydia might include:

For men, symptoms of chlamydia might include:

Around 3 in 4 women with chlamydia don’t show any early symptoms. For men, the proportion is about 1 in 2 men. Women can have an infection for years and men can be infected for months without knowing.

In women, chlamydia usually infects the cervix (the neck of the uterus). In men, it infects the urethra (the tube inside the penis that carries urine and semen) and the testicles. Chlamydia can also infect the anus, the throat or the eyes.

CHECK YOUR SYMPTOMS — Use the sexual health and lower-body Symptom Checker to find out if you need to seek medical help.

How do people get chlamydia?

Chlamydia can spread when you have unprotected sexual contact with someone who already has the infection. This means vaginal, oral or anal sex without using a condom.

Transmission occurs because the bacteria that cause chlamydia live and grow in the fluids that are secreted during sexual activity. If you have chlamydia, there is a 30% to 50% chance of your partner catching it every time you have unprotected sex.

Since chlamydia often has no symptoms, you probably won’t know whether your partner has it.

Chlamydia can’t spread from toilets, swimming pools or usual contact with people. It only spreads through the sharing of genital fluids.

Newborn babies, however, can get chlamydia through their mother during childbirth.

Chlamydia infections can live in the nose, genitals or rectum for more than 2 years.

How is chlamydia diagnosed?

It’s easy to test for chlamydia. Your doctor may ask you to have a sample taken from the vagina, cervix, throat, anus or penis. Or, you may be asked to produce a urine sample. Once the sample is collected, it is sent to a laboratory for testing. STI test results usually come back within a week.

There are 2 main types of tests:

Nucleic acid amplification test (NAAT)

The most common test for chlamydia, this is a simple, non-invasive test during which you collect a swab or urine sample yourself (called 'self-collection'). A doctor can assist in taking a swab if you prefer.

The sample is then sent to be tested to see if there is genetic material that indicates the presence of chlamydia bacteria. Results come back quicker than the traditional culture test.

Culture test

A sample is taken and checked to see whether the Chlamydia trachomatis bacteria is actually present and growing. While a culture test takes longer to process, it may be needed to provide the doctor with extra information.

If you’re under 30 and sexually active, it’s recommended you get checked for chlamydia and other STIs, regardless of whether you’ve ever had it before. You can screen for chlamydia while getting other check-ups — for example, women can have a chlamydia screening while getting a cervical screening test. For men who have sex with men, screening for chlamydia every 3 to 6 months is recommended.

If you suspect you or your partner have chlamydia, you should both get tested straight away — even if you don’t experience any symptoms.

Chlamydia is a notifiable disease in Australia, which means your doctor or nurse must let government health authorities know if you have chlamydia. This is so an accurate number of infections can be tracked.

You will also be asked to get in touch with any sexual partners from the past 6 months — this is known as contact tracing — so they can be informed, tested and treated for chlamydia. This will help stop the spread of chlamydia.

How is chlamydia treated?

Once confirmed, chlamydia is easy to treat with antibiotics (such as doxycycline or azithromycin). Normally, only a single course is needed to clear the infection.

You may be asked to start antibiotics even before your test results come back. If your chlamydia infection is causing symptoms, you may need a longer course of antibiotics. Both you and your partner need to be treated.

If your doctor tells you that you have chlamydia, avoid sex (vaginal, oral or anal) until you have finished the full course of treatment, and for at least 1 week after your last dose. This is to reduce your risk of spreading the disease. You should have another test 3 months after you have been treated.

You’ll also be asked to avoid sex with any partners from the past 6 months until they have been tested and treated.

Since chlamydia is transmitted through unprotected sex, your doctor may suggest you have other STI screening tests so you can be treated as necessary.

You don’t become 'immune' after getting chlamydia: it’s possible to be infected with chlamydia again. Your doctor may recommend follow-up testing and treatment if necessary.

Can you prevent chlamydia?

You can lower your risk of getting chlamydia and other STIs by:

  • using a condom every time you have vaginal, oral or anal sex
  • not having sex with someone with chlamydia, even with a condom, until they’ve finished treatment and 1 week has passed since their last dose of antibiotics
  • regularly getting tested for STIs, especially if you are under 30 and sexually active

Remember that most people with chlamydia don’t show any symptoms and don’t know they have it, so feeling 'well' does not mean that you or your partner are not infected. If in doubt, get tested.

If you have chlamydia, you can help reduce the spread by letting your recent sexual partners know so they can get tested and treated.

Are there complications of chlamydia?

Chlamydia can cause serious complications if it isn’t treated promptly and properly.

Untreated chlamydia can trigger arthritis, skin rashes, and inflammation in the eye or rectum.

For women, chlamydia can spread into the uterus and the fallopian tubes and cause pelvic inflammatory disease (PID). This can cause problems with pregnancy, such as ectopic pregnancy. Women with untreated chlamydia have up to a 1 in 12 chance of becoming infertile. In men, chlamydia can spread to the testicles and the tubes that carry sperm, causing pain and fertility problems.

Pregnant women who are infected with chlamydia have a higher chance of miscarriage or premature birth. Their babies may also get an eye or lung infection. You can read more about chlamydia and pregnancy here.

Living with chlamydia

Learning you have an STI such as chlamydia can be embarrassing and difficult for you emotionally. It can help to talk to a parent or a friend you trust, or to hear stories from others who have gone through a similar experience.

Resources and support

For more information and support, try these resources:

  • NSW Sexual Health Infolink (1800 451 624; weekdays 9am to 5.30pm) is a non-judgemental information and STI referral service in New South Wales.

  • Family Planning provides sexual health and reproductive services, including STI testing. Get information and find clinics in your state or territory here.

  • The Let Them Know website helps you send free, anonymous text messages or emails to sexual partners to help with contact tracing.

  • Drama Down Under is a website specifically for men with male sexual partners. Learn more about STIs, contact tracing and receive reminders when it's time to be retested.

Other languages

The Melbourne Sexual Health Centre has fact sheets on chlamydia and other STIs in Chinese, Korean and Thai.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: July 2020


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