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Pre-exposure prophylaxis (PrEP)

7-minute read

Key facts

  • Pre-exposure prophylaxis (PrEP) is an anti-viral medicine taken by a person who does not have HIV to lower their chance of infection.
  • PrEP is recommended for people at risk of catching HIV, (for example, if you have a sexual partner who is HIV-positive and not on treatment, or 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 one way you can lower your risk of catching human immunodeficiency virus (HIV). PrEP is a prescription tablet that you can take daily to reduce your risk of infection if you are exposed to HIV.

This medicine is called pre-exposure prophylaxis or ‘PrEP’, because you take the medicine even if you don’t have HIV, with the aim of reducing your risk of catching it.

Truvada is a medicine used as PrEP by people without HIV, and well as an anti-HIV medicine used by people who already have 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 to prevent infection. 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, to reduce your chance of infection. To be effective, PEP must be started within 72 hours of exposure.

For more information on PEP, visit the get PEP website.

Who should consider taking PrEP?

PrEP is recommended for:

Your doctor can also help you decide if PrEP is right for you.

How often should I take PrEP?

PrEP is typically prescribed for use every day. But new research has shown that there are other ways of taking PrEP that are also effective. Talk to your doctor about which regimen might be most suitable for you:

Daily

If you take PrEP daily, you will be protected from HIV for as long as you take it. Another advantage is that you can get into a routine of taking a pill every day. You will need to start taking the pills for a certain time period before you have sex (how long will depend on your circumstances), and then one pill every 24 hours. Your doctor can give you more information.

On-demand

Cis males who have sex with other males may be able to take PrEP only when they need it. This option may work for males who do not have anal sex frequently, or who do not want to take a medicine every day. You need to take 2 pills at least 2 hours before sex and then 1 pill every 24 hours for the next 2 days. It is important to get the timing right, so speak with your doctor to make sure this regimen is right for you.

Periodic

PrEP is taken only during the period you need it, such as when you are planning on having a lot of sex. There are different rules for periodic PrEP depending on how you identify. Your doctor can explain these to you.

The pills should be taken with food.

How effective is PrEP?

If you take it correctly, PrEP lowers the risk of infection with HIV by 99%. It is important to start taking the pills before you have sex with someone who has HIV.

Note that 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.

It also does not protect against other sexually transmitted infections (STIs), so you should still use a condom when you have sex.

Are there side effects of PrEP?

Side effects are rare, but some people may develop nausea, diarrhoea or a headache. These side effects usually pass quickly.

Some people who use PrEP, especially those who have high blood pressure or diabetes, may be at increased risk of kidney and liver problems, so your doctor will check these regularly. Your doctor will let you know about any other relevant risks depending on your circumstances.

Where can I get PrEP?

Your doctor or sexual health clinic can give you a prescription for PrEP. It is subsidised by the Government through the Pharmaceutical Benefits Scheme (PBS) for Australian residents who hold a current Medicare card. You can also visit the PrEPaccessNOW website for more information on accessing PrEP.

Your doctor will first check your HIV status and whether you have any other STIs or kidney problems. They will discuss the risk of infection and the possible side effects of PrEP. You can then buy the pills at a pharmacy.

Once you start taking PrEP, you will need to visit the doctor regularly and have HIV and STI checks every 3 months.

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Last reviewed: August 2022


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