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Pre-exposure prophylaxis (PrEP)

5-minute read

What is PrEP?

Over the past few years, there have been some important new developments in the prevention of HIV infection. In particular, there is now a tablet subsidised by the government that you can take daily to reduce your risk of becoming infected if exposed to HIV. This type of medication is called pre-exposure prophylaxis or PrEP.

PrEP is an anti-HIV medicine called Truvada that is taken by a person who does not have HIV to lower their risk of infection.

Although they sound similar, it is important not to confuse PrEP 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 taken by someone who might have been exposed to HIV, with the aim of preventing 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:

  • men (cis and trans) and transgender women who have anal sex with men and do not always use condoms
  • heterosexual men whose partner is HIV positive and are trying for a baby
  • people who have a history of sexually transmitted infections such as anorectal gonorrhoea and chlamydia
  • people who inject drugs
  • sex workers
  • men and women who have sex without condoms with people who use drugs
  • men and women whose partners have HIV

Types of PrEP

Initially PrEP was prescribed for use every day. But new research has shown that there are other ways of taking the pill that are also effective. Talk to your doctor about whether you should take PreP:

  • daily: you are always protected from HIV, and the advantage is that you can get into a routine of taking the pill every day. You will need to start the pills before you have sex and then 1 pill every 24 hours. Your doctor will advise you.
  • on-demand: cis men who have sex with other men may be able to take PrEP only when they need it. This option may be for men who do not have anal sex frequently, or who do not want to take daily medication. 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.
  • periodic: PrEP is taken only during the period you need it, such as when you are 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 does not protect against other 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. People who have high blood pressure or diabetes may be at increased risk of kidney and liver problems, so your doctor will check these regularly.

Where can I get PrEP?

PrEP can be obtained with a prescription from your doctor or sexual health clinic. 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 tests every 3 months.

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Last reviewed: April 2021


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