Common STIs: Causes, Treatment and Prevention

Common STIs are infections passed on through vaginal, anal or oral sex and close skin contact, and many of them cause no symptoms at all, which is why a test tells you far more than waiting for signs. Most are simple to test for with a urine sample or a blood test, and most can be cured or well controlled. This guide explains how common STIs spread, what to look out for, how they are treated and when to get checked.

Key takeaways

• Chlamydia is the most frequently diagnosed bacterial infection passed on through sex in Australia, and most people who have it feel nothing.
• Bacterial infections can be cured with prescription medicine; viral infections such as herpes and HIV are controlled rather than cured.
• Condoms, vaccination and regular testing are the three habits that lower the risk of passing an infection on.
• A Medio doctor can arrange testing by phone, but some infections need an examination or an injection in person.

The Most Common STIs in Australia

Some of the most common STIs in Australia are chlamydia, gonorrhoea, genital herpes, human papillomavirus (HPV) and syphilis. Chlamydia is diagnosed most often, especially in people in their late teens and twenties, and HPV is so widespread that most sexually active people will have it at some point. The table shows how these five STIs differ.

A routine STI health check usually covers chlamydia, gonorrhoea, syphilis and HIV, and sometimes hepatitis B. It does not include herpes or wart testing unless there is a sore or wart to look at.

STI Symptoms to Watch For

STI symptoms are the changes an infection causes in or around the genitals, bottom, throat or skin, and many people with common STIs have no symptoms at all. When symptoms do show up, the usual ones are an unusual discharge from the vagina or penis, stinging or burning when you pass urine, itching, a lump or ulcer, pain during sex, and pain low in the tummy or in the testicles.

Symptoms of chlamydia, when there are any, tend to appear within a few weeks of contact: a change in vaginal discharge, stinging when passing urine, bleeding after sex or between periods, or a dull pelvic ache. Men may notice a discharge from the penis or a sore, swollen testicle. Because the infection is so often silent, chlamydia that is never found can lead to pelvic inflammatory disease and trouble getting pregnant later.

Symptoms of herpes usually start with tingling or itching, followed by small fluid-filled blisters that burst and leave tender sores, which can take a few weeks to heal the first time. The first outbreak can come with fever and aches, and later ones tend to be milder and shorter. Condoms lower the risk of herpes but do not cover all the skin that carries it, and sex toys should be washed or given a fresh condom between partners. Any of these symptoms is a good reason to talk to a doctor rather than wait and see.

How STIs Pass Between Partners

STIs pass between partners through vaginal, anal and oral sex, through close skin-to-skin contact of the genitals, and for a few infections through blood. Chlamydia and gonorrhoea travel in semen and vaginal fluid, while herpes (HSV) and the wart virus spread from skin to skin, so a condom cuts the risk without removing it. Herpes is most easily passed on when blisters or tingling are present, but it can also pass on when the skin looks completely normal. HIV and hepatitis B can also spread through blood, including shared injecting equipment, and some infections, syphilis among them, can pass to a baby during pregnancy or birth. Because so many common STIs cause no signs, people often pass them on without knowing. That is why a regular STI health check makes sense for anyone with a new partner, and why tests for STD and STI screening are routine at a sexual health clinic or a general practice.

Bacterial, Viral and Parasitic Infections

Every sexually transmitted infection belongs to one of three groups: bacterial infections, which the right medicine cures; viral infections, which can be treated or kept under control but mostly not cured; and parasitic infections, which are cured with treatment. Chlamydia, gonorrhoea, syphilis and Mycoplasma genitalium are bacterial. Herpes, human papillomavirus, HIV and hepatitis B are viral. Trichomoniasis is caused by a tiny parasite and can spread on shared sex toys, while pubic lice and scabies spread through close body contact.

Many STDs look alike from the outside. A rash, genital itch or discharge can occur with a bacterial, viral or parasitic cause, so a doctor confirms which one it is with tests instead of judging by appearance. Most tests for STD and STI screening need only a urine sample or a self-collected swab and a blood test. The doctor writes a pathology request, which some people call an STD form, and you take it to a pathology collection centre; a sexual health clinic can also do the whole check on site.

How STIs Are Treated

STIs are treated according to their cause: bacterial and parasitic infections are cured with prescription medicine, and viral infections are kept under control with antiviral treatment. Chlamydia is usually cured with a short course of antibiotic tablets, trichomoniasis with tablets too, while gonorrhoea and syphilis usually need an injection given in person. Antibiotics, and the antiviral tablets used for genital herpes, are only available on prescription in Australia, so a doctor chooses the one that suits you once the infection is confirmed. For genital herpes, antiviral tablets can shorten an outbreak or, taken every day, make outbreaks less frequent.

Partners need testing and treatment too, and it is safest to avoid sex until the doctor says it is safe, usually a week after treatment, and until partners have been treated. A repeat chlamydia test about three months later checks for reinfection, which is common. Where can you get tested for STDs and treated in one place? General practices, sexual health clinics and family planning services can all do both, and any symptom that returns or does not settle after treatment is worth raising with the doctor.

Prevention of Sexually Transmitted Infections

Preventing an STI comes down to three habits: using condoms or dental dams, staying up to date with vaccines, and testing regularly so infections are found and treated early. Condoms used every time, from start to finish, greatly reduce the risk of most STDs, including HIV, which can progress to AIDS without treatment. People at higher risk of HIV can also talk to a doctor about a prevention medicine, PrEP, which is only available on prescription in Australia. Regular testing matters because infections left alone can cause complications such as pelvic inflammatory disease, long-term pain and trouble getting pregnant.

Vaccines protect against two of these infections. The HPV vaccine, given free to young people through the school vaccination program, prevents the types behind most genital warts and most cervical cancers, and catch-up doses are available for some adults. Hepatitis B vaccine is part of the childhood schedule and is recommended for adults at risk who are not already immune. Cervical screening every five years from age 25 then checks for the virus before it causes a problem.

Genital herpes and genital warts need extra care because they spread through skin that a condom does not always cover. Avoiding sex while sores or warts are present lowers the chance of passing them on, and daily antiviral treatment for herpes, when a doctor recommends it, lowers it further. Bleeding between periods, a new lump or pain after sex is a reason to get checked instead of waiting for it to pass.

When to Get an STI Test

An STI test is worth having whenever you have symptoms, a new partner, a partner with an infection or a condom that broke, and once a year if you are sexually active and under 30, or more often with several partners. Pain or burning on urination, a discharge or a genital sore is a reason to test now rather than wait for a routine check. Tell the doctor about your partners, the kinds of sex you have and whether you share toys, because that decides which samples you need. A chlamydia test is usually just a urine sample or a self-collected vaginal swab, and throat or anal swabs are taken only when relevant. Many people put off testing for STDs out of embarrassment, but doctors do these tests every day.

Where can you get tested for STDs? A GP, a sexual health service or a family planning service can arrange it, and a Medio doctor can send an online pathology request after a phone consult. See a doctor in person the same day for severe pelvic or testicular pain, fever with pain in the genitals or heavy bleeding, and call 000 if anything feels life-threatening.

HIV, the Human Immunodeficiency Virus

HIV, the human immunodeficiency virus, attacks the immune system's CD4 cells and, without treatment, slowly weakens the body's ability to fight infection. It passes on through blood, semen, vaginal and anal fluid and breast milk, most commonly through anal or vaginal sex without a condom or through shared injecting equipment. It does not spread through kissing, hugging, sharing cups or toilet seats, and many people have no signs of it for years.

An HIV test is a blood test that a GP can add to the same pathology request, or STD form, used for the rest of an STI check. Medio's doctors consult by phone, so STD testing in Melbourne and across Victoria works the same way as it does in any other state. Treatment has changed what HIV means: daily medicine keeps the virus under control, and a person whose viral load stays undetectable does not pass HIV on through sex.

Stages of HIV Infection

HIV infection moves through three stages when it is not treated: acute infection, chronic infection and AIDS. In the acute stage, two to four weeks after exposure, flu-like symptoms can occur, such as fever, a sore throat, a rash, swollen glands and mouth sores, and they settle on their own, so many people do not link them to HIV. The chronic stage can last ten years or more with few or no symptoms while the virus keeps damaging the immune system.

AIDS is the late stage, when the immune system is so weakened that unusual infections and some cancers take hold, and infections such as herpes simplex can flare more often and heal slowly. Starting HIV treatment early and taking it every day stops this progression, and people on treatment can expect a near-normal life span. Anyone who may have been exposed to HIV in the past 72 hours should go to an emergency department or sexual health service straight away and ask about post-exposure medicine (PEP), which is only available on prescription.

Summary

Common STIs often cause no symptoms, so a test tells you more than waiting for signs. This guide covered how they spread, the symptoms to watch for, treatment, prevention, when to test and how HIV progresses. If you are worried about common STIs, a Medio doctor can assess your risk and advise you by phone, and where the doctor thinks it right, send a pathology request, an eScript or a referral to a sexual health service.

Frequently asked questions

What are the different types of sexually transmitted infections (STIs)?

The three main types of STI are bacterial, viral and parasitic. Bacterial ones include chlamydia, gonorrhoea and syphilis, viral ones include herpes, HIV and hepatitis B, and parasitic ones include trichomoniasis, pubic lice and scabies. Some of the more frequent ones cause no symptoms, so testing is the only way to know.

What is the fastest way to treat STI?

Treatment depends on which infection you have, so the first step is a test that names it. Bacterial infections such as chlamydia are usually cured with a course of antibiotics, which are only available on prescription in Australia, once a doctor confirms the infection. Viral infections are managed rather than cured. Taking every dose as directed, avoiding sex until treatment is finished and having partners tested all help the treatment work.

Can a doctor help with common STI(s)?

Yes. A doctor can help with common STIs by working out which tests you need, arranging them through a pathology request, explaining the results and prescribing treatment if it is suitable. A Medio doctor does this in a telehealth consult by phone; an examination, injection or freezing of warts needs a GP or sexual health service in person.

What is the hardest STI to get rid of?

Viral infections are the hardest to get rid of, because herpes simplex virus (HSV) and HIV stay in the body for life. Both can be controlled well with antiviral treatment. Human papillomavirus (HPV) usually clears by itself within a couple of years, but some types persist and need regular cervical screening.

What are the 7 warning signs of STI?

There is no official list of seven, but the warning signs doctors look for are unusual discharge, pain or burning when passing urine, sores or blisters, lumps or warts, itching, bleeding after sex, and pelvic or testicular pain. Many infections cause none of these, so testing still matters.

How can you tell if a person has an STI?

You cannot tell by looking, because most people with an STI have no visible signs and many do not know they have one. Testing is the only reliable way to know, so it helps for both partners to test before stopping condoms.