Image by Pexel.
What is Australia’s most commonly reported STI?
If you guessed Chlamydia, you are correct. Annual data shows that in 2025, 101 742 people were tested and diagnosed with chlamydia.
Sexual Activity: Unprotected sexual contact
Possible Symptoms: Many people have no signs or symptoms of chlamydia, but symptoms in women can include changes in vaginal discharge, spotting between periods or after sex, burning and stinging when doing a wee, pain during sex or cramps in your lower tummy. These symptoms can start 2-14 days after having unprotected sexual contact.
Test: Urine or swab sample (both can be self-collected), or you can test whilst having another internal screen, such as a cervical screening test. You can also be tested for gonorrhoea at the same time, as many people have both.
Treatment: As chlamydia is a bacterial infection, antibiotics are the treatment. Your sexual partner/s will also require treatment. It is recommended not to have sex (even with a condom) for 7 days after antibiotics start, or you have finished treatment and symptoms are gone –whichever is later.
A follow-up test 3 months after treatment is recommended to confirm that the infection has cleared.
Vaccination: There is no vaccination against chlamydia.
Health Implications:
If left untested and untreated, chlamydia can have long-term impacts on fertility, Pelvic Inflammatory Disease, ectopic pregnancy, arthritis, and inflammation of the eyes/rectum and the urethra.
Chlamydia can be passed from mother to child through childbirth.
Let’s talk all things Gonorrhoea
Also known as the clap, this bacterial STI often goes hand in hand with a chlamydia diagnosis.
Sexual Activity
Transmitted through unprotected sexual contact (vaginal, anal and oral sex). It can also be passed to your eyes from your fingers after touching your genitals.
Possible Symptoms: Symptoms are usually only present if gonorrhoea is affecting the eyes or urethra. These symptoms can include pain and burning when passing urine, sore throat and eye infections such as conjunctivitis. For females, bleeding between periods or after sex, pelvic pain during sex or unusual vaginal discharge could be additional symptoms.
Test: Urine or Swab of the affected area (this can include a self-test)
Treatment: A course of antibiotics is required, and to be taken in full. Following this, a follow-up test will be done to make sure you have cleared the infection. Gonorrhoea can become resistant to antibiotics, so if you have symptoms after starting treatment, speak to your sexual health provider or your GP.
It is recommended not to have sex (even with a condom) for 7days after antibiotics start, or you have finished treatment and symptoms are gone – whichever is later.
Vaccination: There is no vaccination for gonorrhoea.
Health Implications
Untreated gonorrhoea can cause long-term impacts, including Pelvic Inflammatory Disease, infertility, infections in the joints, heart and brain.
Can be transmitted from mother to baby during labour and birth and may cause eye infection or even blindness.
Syphilis
In August 2025, Australia’s Chief Medical Officer declared syphilis a Communicable Disease Incident of National Significance. This means that states and territories around Australia need to increase vigilance, testing, and support for those most at risk of syphilis transmission.
Syphilis transmission was significantly reduced in Australia; however, since 2023, there has been a steady increase in transmission, particularly in congenital syphilis, which has led to infant mortality. You can read more here.
Sexual Activity
In any sexual contact where unprotected skin-to-skin contact occurs. It is very contagious if you have a sore or rash (from the syphilis).
Possible Symptoms
Untreated syphilis can have 4 stages, and so symptoms can be different depending on the stage of syphilis.
1) Primary syphilis – between 10 – 90 days after exposure, you may find a painless lump or sore, often found in the place of sexual contact. These sores can be weepy.
2) Secondary syphilis – can be visible 7 -10 weeks after infection. Red lumpy rashes on palms of hands, soles of feet, chest and back, fevers ,headaches, tiredness and enlarged glands.
3) Latent syphilis – there are often no symptoms for latent syphilis, and diagnosis relies on a blood test. If left untreated, it can either remain latent for years or develop into tertiary syphilis.
4) Tertiary syphilis can impact the brain, spinal cord, eyes and bones.
Test
If you are symptomatic (in primary or secondary syphilis), a swab will be taken from these, and a blood test will be taken to confirm the diagnosis.
Treatment
As syphilis is a bacterial infection, antibiotics are used for treatment. It can be important to avoid all sexual contact for 7 days after you start treatment. Encourage your sexual partners within the past 12 months to be tested and treated to prevent re-infection and get tested at 3, 6 and 12 months after your diagnosis to make sure the infection has gone away.
Vaccination
There is no vaccination for syphilis.
Health Implications
If left untreated, syphilis can have very serious complications. If you are pregnant or want to have a baby, getting tested is very important as congenital syphilis (passed on from mother to child) can cause serious impacts for the baby (including miscarriage, stillbirth, premature birth, low birth weight, birth defects and death). It is standard now for antenatal care to provide 3 syphilis tests in pregnancy to reduce the chance of the baby acquiring this infection.
If you are concerned you have been exposed to a Sexually Transmitted Infection, speak to your GP, or follow this link to places where you can receive comprehensive Sexual Health Testing.
