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Disease groups:
At a glance
- No vaccine available – read more about prevention
- Nationally notifiable disease
About chlamydia
Chlamydia, also called chlamydial infection, is a common STI caused by the bacterium Chlamydia trachomatis.
The bacteria can cause infection of the:
- urethra (urine tube)
- cervix (the opening of the uterus at the top of the vagina)
- testicles
- mouth and throat
- anus.
Chlamydial infection of the eye can also occur. This is known as trachoma and can lead to blindness if untreated.
Why it matters to public health
Chlamydia is the most commonly diagnosed bacterial STI in Australia. Between 80,000 and 110,000 cases are notified in Australia every year.
It is easy to test for and treat. But as most people don’t develop symptoms, the infection can go unnoticed and untreated and be spread to others.
Untreated chlamydia can lead to long-term complications, including infertility. This is why regular testing for chlamydia and other STIs is important.
Because of these major impacts we:
monitor and report on chlamydia in Australia
develop and implement national STI strategies.
Symptoms
If you’re looking for advice about your own health or treatment options, see healthdirect or speak with a qualified healthcare professional. Our role is to provide public health advice – information and guidance that helps prevent disease, protect communities and improve wellbeing at a population level.
Up to 9 in 10 people who have chlamydia have no symptoms.
For those who get symptoms, these can include:
- burning or stinging sensation when urinating
unusual discharge from the vagina or penis
pain in the testicles or pelvic area
vaginal bleeding or spotting between periods or after sex
pain during or after sex
anal pain or discharge.
If not treated, chlamydia can cause complications such as:
- inflammation of the joints, eyes, rectum and genital areas
- infertility
- pelvic inflammatory disease
- ectopic pregnancy (pregnancy outside the uterus)
- miscarriage
- premature birth.
Newborns who are infected at birth can develop eye and lung problems.
Chlamydia increases the risk of getting HIV and spreading it to others.
Read more about the symptoms, diagnosis and treatment of chlamydia.
healthdirect’s symptom checker can help you decide whether to see a health professional.
Onset of symptoms
Symptoms, if present, usually start between 2 and 14 days after getting infected.
How it spreads
Chlamydia mainly spreads through unprotected vaginal, anal or oral sex with an infected person. It can spread through sexual networks.
People with chlamydia can spread the infection even when they don’t have symptoms.
It can spread from the genitals to the eyes through contact with fingers or hands.
Chlamydia can spread from a pregnant person to the baby during birth.
People can get chlamydia more than once.
Infectious period
People with chlamydia can spread the infection from the time they are infected, even if they have no symptoms.
People who receive treatment are usually infectious until 7 days after they finish antibiotics.
It’s not well known how long people can spread the bacteria if their infection is left untreated. But this might range from months to years, depending on where in the body the infection is.
Prevention
Protect yourself
There is no vaccine for chlamydia.
The best way to protect yourself against chlamydia is to practise safe sex and follow the same precautions used to prevent other STIs. This includes always using barrier protection, such as condoms and dental dams.
Know the symptoms of chlamydia and what to do if you or a sexual partner develops them. But remember that not everyone gets symptoms, so regular sexual health checks and STI testing are important.
If you are a gay or bi+ cisgender man or trans woman, speak with your healthcare professional to find out whether you are eligible for doxycycline post-exposure prophylaxis (also called Doxy-PEP). Doxy-PEP can be taken after sex to reduce the risk of some STIs.
Read more information for GBMSM.
If you have had an STI you might be at risk of getting infected again. After chlamydia treatment, you should:
- be tested for other STIs, including syphilis and HIV
- be tested again after 3 months
- continue to get regular sexual health check-ups.
Protect others
If you’ve been diagnosed with chlamydia, you should:
- not have any type of sexual contact until cleared by your healthcare professional – usually 7 days after finishing antibiotics and when symptoms have resolved
- tell anyone you have had sex with during the past 6 months, so they can get tested and treated – you can do this anonymously through:
- Let them know
- The drama down under
- Better to know
- your healthcare professional
- not have sex with current or previous partners until they have been tested and treated (if necessary) and are no longer infectious.
Read more ways to prevent STIs.
Priority groups and settings
Some people are at greater risk of getting chlamydia or getting very sick from it.
Chlamydia can spread in:
- venues that offer sex on premises
- parties or other social events where intimate contact occurs.
If you are at greater risk, it is especially important to:
- take steps to protect yourself
- see a healthcare professional if you are exposed to chlamydia or develop symptoms.
People at greater risk of severe disease
Chlamydia poses a greater risk of severe illness for:
- people who don’t receive appropriate antibiotic treatment early
- females and other people with a uterus
- babies born to someone with chlamydia at the time of the birth.
If you are pregnant, get tested and follow your healthcare professional’s advice. Treatment during pregnancy is safe.
People at greater risk of exposure
Everyone who is sexually active is at risk of being exposed to chlamydia.
People might be more likely to be exposed if they are:
- aged under 30 years
- gay, bisexual or other men who have sex with men (GBMSM), including transgender and gender-diverse people
- people of any gender who have sexual partners who are GBMSM
- sexually active in an area where chlamydia is prevalent.
People can have more than one STI at the same time. Exposure to chlamydia increases the risk of also being exposed to other STIs.
Diagnosis and treatment
Chlamydia is diagnosed by:
- a urine test
- a swab of the infected area, such as the vagina, cervix, anus or throat (sometimes swabs can be self-collected).
You can use healthdirect’s directory to find a health service near you.
Chlamydia is treated with antibiotics.
Your healthcare professional will ask you to return for another test after 3 months to check for reinfection.
Read more about how to manage or treat chlamydia.
Surveillance and reporting
Chlamydial infection is a nationally notifiable disease – these are diseases that present a risk to public health.
Health authorities in each state and territory report new laboratory confirmed cases to us daily through the National Notifiable Diseases Surveillance System.
We work with the Kirby Institute to publish annual STI surveillance reports.
These are part of our surveillance activities, which help us monitor case numbers around the country and understand disease patterns.
We analyse the data and report on case numbers and other data through our data visualisation tool, where you can filter and search the latest information.
Outbreaks
State and territory health departments might respond to outbreaks of chlamydia by:
- ensuring appropriate treatment for people with infection
- contact tracing to identify others who might have been exposed and recommending testing, if needed
- providing information about STIs and how to prevent them.
Read more about how the Australian Government defines and plans for outbreaks.
Support
For information about chlamydial infection in your state or territory, see:
If you need mental health support, see a list of organisations, websites and services that offer support, counselling and information.