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Sexually transmissible infections (STIs)

A sexually transmissible infection (STI) is a disease that can be transmitted by unprotected sex.

About sexually transmissible infections

For more than a decade, there’s been an increase in the number of STIs in Australia. Chlamydia is the most common STI and reported numbers have quadrupled in the last 10 years. Eighty percent of reported cases are in 15-29 year olds.

Symptoms of sexually transmissible infections

Some people with an STI don't have any symptoms at all. If you do have symptoms they might include:

  • An unusual discharge from your vagina, penis or anus
  • In women, bleeding after sex or between periods
  • Sores, blisters, warts, rashes, irritation or itching near your genitals or anus
  • Pain on passing urine, or needing to pass urine more often than usual
  • Pain during sex
  • Pelvic or lower abdominal (tummy) pain

It's important to be tested if you think you may have an STI. If untreated, some STIs may lead to complications and serious health problems, such as infertility.

STIs and fertility

Common STI's such as chlamydia and gonorrhoea can have an impact on your fertility. Find out how:

Causes of sexually transmissible infections

Most STIs are caused by micro-organisms such as bacteria or viruses. These infections can be passed from one person to another during intimate physical contact, such as through sexual intercourse, non-penetrative genital contact, sharing sex toys with partners and oral sex.

Diagnosis of sexually transmissible infections

If you think you may have an STI, see your GP or go to a sexual health clinic.

You don't have to ask your GP to refer you to a sexual health clinic; you can make your own appointment. All visits are confidential and you don't have to give your real name. Details won't be sent to your GP without your consent.

You’ll usually need to have a physical examination, which for women may include an internal examination. Swabs (to get cells or traces of infection) and blood and urine samples may also be taken.

Types of sexually transmissible infections

Some of the most common STIs are discussed in more detail below.


Chlamydia is the most common STI and often affects people under the age of 25. It's caused by a type of bacterium that infects the cervix (the neck of the womb), urethra (the tube that carries urine from your bladder and out through the penis or vulva), rectum (back passage), throat and/or eyes.

In women, symptoms include:

  • Lower abdominal pain
  • Bleeding after sex
  • Bleeding in between periods
  • Unusual vaginal discharge
  • Pain when passing urine.

In men, symptoms include:

  • Discharge from the penis
  • Pain when passing urine.

Symptoms usually occur one to three weeks after getting infected. However, about 70 percent of women and 50 percent of men with the infection don't have any symptoms.

If you have a rectal infection there are rarely any symptoms, but you may have a discharge and it can be painful.

Chlamydia can be treated with antibiotics.

Genital herpes

Genital herpes is caused by the herpes simplex virus (HSV). A genital herpes infection usually causes painful ulcers or sores in or around the genital area or around the anus. These usually develop four to seven days after infection. You may also have pain when you pass urine, a stinging or tingling in your genital area or anus and feel generally unwell. Some people don't have any symptoms or have sores that aren't painful.

After the first or primary episode, you may have repeat attacks of herpes. These don't tend to be as severe as the first attack and don't last as long (10 days compared with 20 for the primary episode).

There’s no treatment to remove the herpes virus from your body. However, your doctor can prescribe antiviral tablets, which can help the outbreak clear up faster and reduce the severity of your symptoms.

Genital warts

Genital warts are a very common STI and are caused by certain strains of the human papilloma virus (HPV). The warts are fleshy growths that appear on or around your genitals and anus. They are usually painless but can itch and may bleed or become inflamed. It usually takes one to three months for warts to appear after you're infected, but it can take much longer.

Warts sometimes disappear without treatment within six months to a year. However, they can be treated with a chemical solution or liquid nitrogen (cryotherapy). Surgery or laser treatment are also options, although sometimes repeat treatments are necessary.


Gonorrhoea is caused by bacteria that infect the urethra, cervix, rectum, mouth and throat. Symptoms can appear one to 14 days after you become infected or not until many months later when the infection has spread to other parts of your body.

In women, symptoms include a thick vaginal discharge, pain when passing urine, lower abdominal pain and bleeding between periods or heavier periods. However, around half of all women with gonorrhoea don't have any symptoms. Symptoms in men include a white, yellow or green discharge from the urethra and pain when passing urine. About 10 percent of men may not have any symptoms.

If your throat is infected you probably won't have any symptoms. This is also true if your rectum is infected, but occasionally it can cause discharge, pain or discomfort.

Gonorrhoea can be treated with antibiotics. As with chlamydia, gonorrhoea can cause serious health and reproductive problems if it isn't treated.

Hepatitis B

Hepatitis B is caused by a virus (HBV) that is highly infectious. Symptoms of hepatitis B can appear about one to six months after you become infected and include jaundice (yellowing of your skin and eyes), dark urine, extreme tiredness, feeling or being sick and abdominal pain. HBV can also cause a chronic liver infection that can later develop into cirrhosis or liver cancer.

Some people with hepatitis B never have any symptoms. They are known as asymptomatic carriers as they are still infectious and can unknowingly pass on the disease to others.

Most people with acute hepatitis B recover without treatment. There’s a range of medicines available such as antivirals or those that help your immune system fight the disease. A vaccine is also available to prevent the disease.


The human immunodeficiency virus (HIV) attacks your immune system. About 50 percent of people have flu-like symptoms within a few weeks of being infected.

Infection with HIV can lead to Acquired Immune Deficiency Syndrome (AIDS). If HIV infection is left untreated over a long period of time, it can damage a person's immune system and put them at high risk of developing related infections or cancers. At this advanced or late stage of HIV infection, a person is said to have AIDS.

There is no treatment to remove HIV from your body. However, your doctor can prescribe antiretroviral treatment or combination therapy to reduce the level of HIV in your blood.

Pubic lice

Pubic lice mainly live in your pubic hair but they can infect other body hair including your eyebrows and eyelashes. They lay eggs (nits) that stick to your hairs.

Symptoms include itchy red spots and you may also notice black powdery spots from the lice in your underwear. It can take one to three weeks after infection for symptoms to appear.

Public lice can be treated with lotions or shampoos.


Syphilis is a bacterial infection. It's less common in Australia than it used to be, although it’s increasing in non-indigenous Australian men in urban and regional areas.

The first sign of syphilis in the primary stage is a painless sore or lump usually found on or near the genitals, mouth or anus – wherever you were first infected. This can develop between nine and 90 days after infection. In the secondary stage of the illness, you may feel generally unwell with flu-like symptoms and a rash. This may last around four to eight weeks after the lump or sore first appeared.

These symptoms may gradually clear up on their own, but it's important to treat syphilis as soon as possible. Over time it can cause major health problems, such as damage to your heart, respiratory system and nervous system. Syphilis can be treated with antibiotics in tablet form or as an injection.

Prevention of sexually transmissible infections

Simple measures can reduce your risk of catching an STI. Safer sex methods include using condoms for vaginal, anal and oral intercourse and when sharing sex toys. This can help prevent the spread of HIV and reduce the risk of many STIs.

If you're diagnosed with an STI it's important to contact your previous partners who may be at risk, to prevent them from spreading the infection to others. If you’re uncomfortable doing this personally, sexual health clinics can send anonymous notifications on your behalf.

If you think you're at risk of catching an STI, consider having a check-up at a sexual health clinic every few months. Once diagnosed with an STI, it's important to wait until the doctor gives you the all clear before you have sex again.

Further information

Sexually Transmissible Infections

Sexual Health and Family Planning Australia


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Last published: 30 July 2011

This information has been developed and reviewed for Bupa by health professionals. To the best of their knowledge it is current and based on reputable sources of medical research. It should be used as a guide only and should not be relied upon as a substitute for professional medical or other health professional advice.

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