Pre-exposure prophylaxis (PrEP)
Key facts
- Pre-exposure prophylaxis (PrEP) is an anti-viral medicine taken by someone who does not have HIV to lower their chance of catching HIV.
- PrEP is recommended for people at risk of catching HIV. e.g. if you have a sexual partner who is HIV-positive and not on treatment, or if you are sexually active and do not use condoms.
- PrEP is usually taken daily, but in some cases, it may still be effective if you take it less often.
- You can get a prescription for PrEP from your doctor.
- It's a good idea to talk to your doctor about your circumstances, so they can recommend the best PrEP regimen for you.
What is PrEP?
Pre-exposure prophylaxis (PrEP) is a prescription medicine you can take to lower your risk of catching human immunodeficiency virus (HIV). PrEP comes as a tablet or injection. Medicines are used to treat HIV (called antiretrovirals) are also used as PrEP.
This medicine is called 'PrEP' because you take it if you do not have HIV. You are supposed to take PrEP before a potential exposure to HIV.
Although they sound similar, it is important not to confuse PrEP (pre-exposure prophylaxis) with PEP (post-exposure prophylaxis).
- PrEP is taken by people who do not have HIV. It is used to reduce the chance of becoming infected with HIV, if you are exposed. You must be HIV negative before you take the first dose.
- PEP is short course of anti-HIV medicines you can take if you might have been exposed to HIV. PEP reduces your chance of HIV infection. To be effective, you must start PEP within 72 hours of exposure.
For more information on PEP, visit the get PEP website.
PrEP is now listed on the Pharmaceutical Benefits Scheme (PBS). This means any doctor can prescribe PrEP to people who need it.
Who should consider taking PrEP?
PrEP is recommended for people who are at risk of getting HIV, including:
- males (cis and trans) and transgender females who have sex with males and do not always use condoms
- people with HIV-positive sexual partners who are not on antiretroviral medicines or have a detectable viral load
- people who have an HIV-positive partner and are trying for a baby
- people who have a history of sexually transmitted infections (STIs) such as anorectal gonorrhoea and chlamydia
- people who inject drugs
- sex workers
- people who have sex without a condom with people who use drugs
Your doctor can help you decide if PrEP is right for you.
How often should I take PrEP?
You can take PrEP daily, on-demand or periodically.
Based on how you identify and your sexual activities, your doctor will can recommend the best regimen and what dose of PrEP for you. Your health professional will give you more information and guidance.
It is very important you take your PrEP exactly as your doctor recommends so that it can protect you from HIV.
Daily PrEP
Taking your PrEP medicine every day is the most common way to take PrEP in Australia.
If you take PrEP daily, you will be protected from HIV for as long as you take it. This can be helpful if you have frequent potential HIV exposures Another advantage is that you can get into a routine of taking a pill every day.
Ask your doctor how long you need to take PrEP for before it is likely to be effective.
On-demand PrEP
Taking PrEP on-demand is only recommended for cis males who have sex with other males. There is not enough research to show that it is effective in other groups.
This protocol might suit you if you do not have sex very often or if you can plan or delay potentially risky sex.
If you want to take PrEP on-demand, you will have to follow a special protocol for it to protect you from HIV:
- Take 2 pills at least 2 hours before sex.
- Take 1 pill 24 hours later.
- Take another pill another 24 hours later.
If you continue to have sex, for ongoing protection, take another pill every 24 hours. After the last episode of sexual activity, continue to take your pills for another 2 days (1 pill each day).
If you are living with chronic hepatitis B, on-demand PrEP is not suitable for you. Ask your doctor about other options.
Periodic PrEP
If you do not want to or do not need to take PrEP long-term, periodic PrEP could be right for you. For example, you might take it during a period when you think you will be having sex frequently.
There are different rules for periodic PrEP, depending on how you identify. Ask your doctor for more information.
The pills should be taken with food.
How effective is PrEP?
If you take it correctly, PrEP lowers your risk of infection with HIV by 99%. It is important to start taking the pills before you have sex with someone who is HIV-positive.
If you are already infected with HIV, taking PrEP does not reduce the risk of transferring the virus to other people through sexual contact or blood.
PrEP does not protect you against other STIs. You should still use a condom when you have sex.
What are the side effects of PrEP?
PrEP can cause some rare side effects such as:
- headaches
- nausea
- feel gassy (flatulence)
- kidney problems
- liver problems (very uncommon)
Most of these side effects go away within a month of starting PrEP.
If you take PrEP you may be at risk of kidney and liver problems, and especially if you have high blood pressure and diabetes. See your doctor regularly to keep an eye on your kidney and liver function.
Your doctor will let you know about any other relevant risks depending on your circumstances.
To search medicines by active ingredient or brand name, use the healthdirect Medicines search feature.
Where can I get PrEP?
There are a few ways you can get PrEP:
- If you have a Medicare card, you can buy PrEP from your local pharmacy. PrEP is subsidised through the Pharmaceutical Benefits Scheme (PBS). Any doctor can give you a prescription.
- If you do not have access to Medicare, you can import a generic version of PrEP from an overseas supplier. You still need a prescription from your doctor. You can even buy a few months' worth of PrEP at once to save money on shipping costs.
Before your doctor gives you a prescription for PrEP, they will check if you have HIV, any other STIs or kidney problems. They will also discuss your risk of getting HIV and possible side effects of PrEP.
After you start taking PrEP, you will need to visit your doctor every 3 months for a check-up and to test for HIV and other STIs.
You can also visit the PrEPaccessNOW website for more information on accessing PrEP.
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Resources and support
- Learn about different ways to access PrEP at the PrEP Access Now website.
- Visit Health Equity Matters, an Australian non-profit organisation that gives a voice to communities affected by HIV/AIDS.
- Visit Get PrEP'D to learn more about preventing getting HIV.
- Read the PrEP patient information booklet at NSW Health — this booklet also has information on PrEP, pregnancy and breastfeeding.
Do you prefer to read in languages other than English?
- Ending HIV has information pages in Arabic, Chinese, Indonesian and Spanish.
- The Victorian Sexual Health Network website has information pages about HIV in Arabic, Chinese, Korean and Spanish.
Looking for information for sexually and gender-diverse people?
- Visit ACON, a NSW based organisation that specialises in HIV prevention, support and lesbian, gay, bisexual, transgender and intersex (LGBTI) health.
Looking for information for Aboriginal and/or Torres Strait Islander people?
- Visit U & ME CAN STOP HIV for resources on HIV for Aboriginal and/or Torres Strait Islander people, communities and health services across Australia.
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Last reviewed: March 2024
