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Chlamydia is the most commonly diagnosed sexually transmitted infection (STI) in Australia, followed by gonorrhoea. Syphilis is less common but has been rising. Many STIs cause no symptoms at all, which is why regular testing matters even when you feel well.
This guide covers the most common STIs in Australia, the latest national figures, how each one is tested and what you can do to protect yourself.
The latest Australian figures
The Kirby Institute’s Annual Surveillance Report 2025, which covers diagnoses made in 2024, reported:
| Infection | Diagnoses in 2024 | Trend |
|---|---|---|
| Chlamydia | 101,742 | Fairly stable; about half were in people aged 20 to 29 |
| Gonorrhoea | 44,210 | Doubled over the past 10 years |
| Syphilis | 5,866 | Doubled over the past 10 years, with a four-fold rise in women |
| HIV | 757 | Down 27% over the past decade |
The Kirby Institute’s summary of the 2024 data also notes that cases of congenital syphilis (passed from a pregnant person to their baby) have more than doubled since 2015. These figures only count infections that were diagnosed, so the true number of infections is likely to be higher.
Common STIs in Australia
Chlamydia
A bacterial infection that often causes no symptoms. When symptoms do occur, they can include pain when weeing, unusual discharge, bleeding between periods or after sex, or testicular pain. Untreated, it can lead to pelvic inflammatory disease and fertility problems. It’s diagnosed with a urine test or swab and treated with antibiotics. Read more in our article on chlamydia symptoms, testing and treatment.
Gonorrhoea
A bacterial infection that can affect the genitals, throat and rectum. Infections in women, and in the throat or rectum, often cause no symptoms; men are more likely to notice discharge or pain when weeing. It’s tested with a urine test or swab. Because some strains are becoming resistant to antibiotics, treatment follows current guidelines, and a test after treatment may be recommended.
Syphilis
A bacterial infection that develops in stages. It may start as a painless sore, followed weeks later by a rash or flu-like symptoms, and can then go quiet for years. Untreated, it can damage the heart, brain and other organs. In pregnancy it can cause miscarriage, stillbirth or serious illness in the baby, so all pregnant people are offered testing. It’s diagnosed with a blood test and is treatable.
Genital herpes
Caused by the herpes simplex virus. Many people never have symptoms, while others get painful blisters or sores that come and go. It’s a long-term infection, but antiviral treatment can shorten outbreaks and reduce the chance of passing it on. A swab of a sore is the main test. See our guide to genital herpes types, symptoms and living well.
Human papillomavirus (HPV)
A very common virus. Most infections clear on their own, but some types cause genital warts and others can lead to cervical, anal and throat cancers. The HPV vaccine is offered through the school immunisation program, and cervical screening every five years (including a self-collected option) checks for HPV in people with a cervix aged 25 to 74.
HIV
A virus that affects the immune system. With modern treatment, people with HIV can live long, healthy lives, and someone with an undetectable viral load doesn’t pass HIV on through sex. HIV is diagnosed with a blood test. PrEP (taken before exposure) and PEP (started within 72 hours after exposure) can prevent infection.
Other infections
Trichomoniasis and Mycoplasma genitalium are less common STIs that can cause discharge or irritation. Your doctor may test for them if you have symptoms.
Who is most affected?
- Young people: about half of chlamydia diagnoses are in people aged 20 to 29.
- Gay, bisexual and other men who have sex with men: higher rates of gonorrhoea and syphilis, so more frequent testing is usually recommended.
- Aboriginal and Torres Strait Islander people, particularly in remote communities, where rates of some STIs are higher.
- Women of reproductive age: rising syphilis rates are a particular concern because of the risk to babies.
How to protect yourself
- Use condoms and dams, which greatly reduce the risk of most STIs.
- Get tested regularly. healthdirect recommends a chlamydia and STI check at least once a year if you’re sexually active and under 30, and with each new partner.
- Get vaccinated against HPV and hepatitis B if you haven’t already.
- If you test positive, let recent partners know so they can be tested and treated.
- Talk to a doctor about PrEP if you’re at higher risk of HIV.
When to see a GP
See a GP for an STI check if you’ve had a new partner, a partner tells you they have an STI, or you notice symptoms such as discharge, pain when weeing, sores, lumps or a rash in the genital area. You’ll need to be seen in person if a doctor needs to examine a sore or lump.
When to get urgent help
- If you may have been exposed to HIV in the past 72 hours, go to an emergency department or sexual health clinic straight away for HIV PEP.
- Go to an emergency department if you have severe pain in your lower tummy or testicles, a high fever, or feel very unwell.
- In an emergency, call 000.
How Teldoc can help
Our AHPRA-registered GPs offer STI testing and treatment by phone or video, 7 days a week from 9 am to 7 pm (Sydney time). The doctor can send you an electronic pathology request and, if you need it, prescribe treatment if clinically appropriate with an eScript sent to your phone. STI consultations are bulk billed for eligible patients with a valid Medicare card; see our fees page. Our sister service STI Doctor focuses only on STI testing and prevention.
Frequently asked questions
What is the most common STI in Australia?
Chlamydia. There were 101,742 diagnoses in 2024, according to the Kirby Institute, with about half in people aged 20 to 29.
Are STIs increasing in Australia?
Gonorrhoea and syphilis diagnoses have roughly doubled over the past decade, while chlamydia has been fairly stable and HIV diagnoses have fallen.
Can you have an STI without symptoms?
Yes. Chlamydia, gonorrhoea, syphilis, herpes and HPV can all cause no symptoms, which is why regular testing is recommended.
Which STIs can be treated?
Bacterial STIs, such as chlamydia, gonorrhoea and syphilis, can usually be cleared with antibiotics. Viral STIs, such as herpes and HIV, are long-term infections, but treatment can manage them well.
This article is general health information and isn’t a substitute for advice from your own doctor. If you’re worried about your health, speak to a GP. In an emergency, call 000.
Medically reviewed by Dr Vafa Derakshan (MBBS, FRACGP), September 2026
