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Pre-exposure prophylaxis (PrEP)

8-minute read

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).

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:

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:

  1. Take 2 pills at least 2 hours before sex.
  2. Take 1 pill 24 hours later.
  3. 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:

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:

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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