What is an STI?

Sexually transmitted infections (STIs) are infections that can be passed on during sexual activity. If you are pregnant, STIs can also be transmitted from you to your unborn baby. If left untreated, STIs can cause serious problems for both you and your baby.

What causes STIs?

STIs are caused by microorganisms such as bacteria, viruses and parasites, and are sometimes called sexually transmitted diseases (STDs). These organisms can pass between people in:

• semen
• blood
• vaginal and other bodily fluids
• faeces (poo)

Many STIs can also be transmitted by:

• close skin-to-skin contact (for example, during foreplay)
• vaginal or anal intercourse
• oral sex
• blood-to-blood contact through open cuts and sores
• sharing needles and other equipment for intravenous (IV) drug use

STIs can also be passed from you to your baby if you are infected during pregnancy or childbirth.

What are the different types of STIs?

There are many different types of STIs. The most common STIs in Australia are:

• chlamydia
• gonorrhoea
• syphilis
• genital warts / human papilloma virus (HPV)

Other STIs include:

• hepatitis B
• genital herpes
• human immunodeficiency virus (HIV)
• trichomoniasis

There are also other infections that, while not strictly classified as STIs, may be linked with sexual activity, such as:

• hepatitis A
• thrush
• bacterial vaginosis
• pubic lice ('crabs')
• scabies
• lymphogranuloma venereum
• mycoplasma genitalium

What are the symptoms of STIs?

Many people with STIs have no symptoms. You might not even know you have an STI until it causes complications, or a sexual partner is diagnosed.

Some people get symptoms such as:

• sores, ulcers or bumps on the genitals, mouth or rectal area
• pain when urinating or during sex
• unusual discharge from the penis or vagina
• unusual vaginal bleeding
• eye infections
• itchiness around the genital region

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

When should I see my doctor?

If you have one or more symptoms of STIs, it doesn’t necessarily mean you have an STI. It’s still a good idea to see your doctor for a check-up.

Your doctor will usually test you for STIs at your first antenatal appointment or when you are planning a pregnancy.

If you think your partner may have an STI, ask your doctor about testing.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

Can having an STI affect my pregnancy?

STIs can affect your ability to become pregnant (your fertility), as well as your pregnancy. Pregnancy doesn't prevent you getting an STI. If you are infected with an STI while you're pregnant, it can cause serious problems for you and your developing baby. Problems include:

• chronic abdominal pain
• pelvic inflammatory disease (PID)
• complications during birth

If you are pregnant, or wanting to become pregnant, you should ask your doctor to test you for STIs, even if you have tested in the past. If you have concerns about getting tested, discuss them with your doctor, or another health professional.

If you do get an STI while you're pregnant, getting early treatment can reduce the risks. Even if the STI can't be cured, there are things that can be done to protect you and your baby.

How can STIs affect my baby?

Some STIs, such as syphilis and HIV, can infect your baby during pregnancy. Others, such as chlamydia and genital herpes, can infect the baby during labour and/or birth.This depends on how the STI is transmitted (passed on).

STIs can increase health risks for unborn babies. These include:

• transmission of the infection to the baby
• premature birth
• low birth weight
• birth differences (defects)
• stillbirth or early death

Some STIs increase the risk of eye and respiratory (breathing) tract infections in newborn babies.

Getting regular medical care during your pregnancy and discussing any concerns you have regarding STIs with your doctor or midwife help reduce the risk of problems caused by STIs during your pregnancy.

How are STIs diagnosed and treated?

Diagnosis of STIs can be tricky because many infections show no symptoms. Untreated STIs stay active in the body and may be passed on to sexual partners, or your baby, without you being aware. This is why it’s important to get tested if you think you may have an STI or are at risk of infection.

Having a test for STIs is simple. The type of test depends on the STI, but tests usually involve one or more of these:

• urine sample
• swab
• blood test
• physical examination

If the screening test shows you have an STI, you may need more tests and treatment to confirm which STI you have.

Many STIs are nationally notifiable diseases in Australia. This means that your doctor must tell local public health authorities about all identified cases. Infections can be tracked, and contacts can be informed to try stop outbreaks and get treated.

Many STIs are curable. STIs caused by bacteria, such as chlamydia, can usually be treated with antibiotics. Other STIs, such as those caused by viruses (for example, herpes) are not always curable, but there may be things you can do to relieve your symptoms. Talk to your doctor about treatment possibilities for you.

Will I be tested for STIs during pregnancy?

Most people will be offered routine tests for some STIs at their first antenatal care appointment, including:

• hepatitis B
• HIV
• syphilis

It is recommended that you have at least 3 tests for syphilis during your pregnancy — at your first antenatal visit, at 26 to 28 weeks, and at 36 weeks or at birth (whichever is earlier).

Depending on your age and circumstances, your doctor may recommend testing for other STIs as well. You can request specific tests for non-routine STIs. Your doctor may include tests for STIs that are prevalent in your region.

What can I do to prevent getting an STI?

You can protect yourself from STIs by not having sex with a partner who could potentially have an STI. Practicing safe sex with condoms (used during penetrative sex) and dental dams (used during oral sex) offers the best protection from STIs.

Other ways to avoid STIs are:

• having sex with one uninfected partner
• limiting the number of sexual partners you have sex with
• avoiding sex with a new partner until you've both been tested for STIs
• getting vaccinated against HPV and hepatitis
• not taking drugs or drinking excessive alcohol (often associated with risk-taking behaviour)

If you are male, getting circumcised reduces your chances of catching some STIs too.

Resources and support

• The Australian Government Department of Health and Aged Care has information about looking after your sexual health.
• The Royal Women's Hospital, Victoria has fact sheets on Having a pelvic or genital examination.
• ReachOut has information and advice about STIs for young people.
• Stay STI Free has information about different STIs and what to do if you have an STI.

Do you prefer to read languages other than English?

Talk Test Treat website has STI information in a range of languages.

Looking for information for Aboriginal and/or Torres Strait Islander people?

Better To Know is a sexual health resource with information about STIs, what to do if you think you may have an STI and where to get tested.