The Science

PrEP is powerful at preventing HIV, and is safe to take.

How do we know this? Well, glad you asked! There have been studies all around the world that have demonstrated that PrEP works. Some of them looked at PrEP in different ways, and have shown more than one way to take PrEP, and how it works differently for some people. 

There's also plenty of NEW research happening that will inform how we take PrEP in the future. Things like different types of drugs - or different methods of using PrEP, such as injections, gels, and implants are all on the horizon. 


First, lets look at what we alreayd know about PrEP!



Where? Between 2007-2011

Where? Peru, Ecuador, Brazil, Thailand, South Africa and the United States. 

Who? Gay/bi men and transgender women

The iPrEx study is one of the big studies that first showed us that PrEP works. In this study they recruited 2,500 gay/bi men and trans women from six different countries. They gave half Truvada, and the other half a placebo - a drug that looks like the real thing, but isn't.

Of the folks that received Truvada, there was a 42% reduction in HIV. This doesn't seem like much, however there were people in that group who didn't take their PrEP, or didn't take it regularly. Of the folks that were tested and had good levels of PrEP in their body, it was more like 92%. That's still not the full story, when they looked deeper - of the people who took their PrEP daily - there was around 99% protection against HIV. 



Where? Between 2011-2012

Where? Peru, Ecuador, Brazil, Thailand, South Africa and the United States. 

Who? Gay/bi men and transgender women

This study was an extension of the original iPrEX study. iPrEP showed us that if you take PrEP it works, if you don't it doesn't. They wanted to look closer at those who did. Of the 2,500 people in iPrEX they followed around half of them, 1225 people. Of that group, some took no PrEP, and the others were asked to keep up PrEP daily. 

Of the people who took PrEP 4 or more times per week, none of them acquired HIV. It confirms that if PrEP is taken with even moderate consistency it is extremely effective. 



Where? Between 2008-2010

Where? Kenya and Uganda

Who? Heterosexual men and women

This study was called the Partners PrEP study because it looked at PrEP for HIV-negative people who had partners who were HIV-positive.

Of the over 4,500 people the study followed, the HIV-negative partners were given either Truvada (a combination of two drugs; tenofivir and emtractibine), Viread (just the tenofivir), or a placebo - with no PrEP drug.   

The Tenofivir alone provided good protection, while the combo in Truvada provided the best protection.

In folks who had the drug detected in their blood at testing,  PrEP cut infections by at least 90%. Adherence to the medication was key to making PrEP work!



Where Can I Get IT?

Fortunately, access has never been so good to access PrEP in Australia. Depending on your location, or circumstances one of the following may be suitable for you to look into access PrEP. In all instances below, you need to frst find a PrEP knowledgable GP who can do all your tests, and then write you a prescription

 Low cost PrEP can be found for purchase online, and is often the cheapest way to access PrEP because of the low cost of generic medications overseas. At around $32 per month for the cheapest option, this is how many people have accessed PrEP for years. for more check out our guide on how to Buy PrEP Online and selecting a supplier to purchase from.

Find a Study: There are clinical studies of PrEP going on across the country with various levels of access regarding numbers of people who can get on board. Price will vary state to state too, but this can be extremely cheap – or even free. To find out if there’s a study in your area head to our PrEP Clinical Studies page

It was recently announced that PrEP would be listed on the PBS, so people accessing PrEP at their local pharmacy will soon be able to pay the PBS co-payment rice for one month of medication. This is convenient, but may not be the cheapest option depending on your circumstances. Our PrEP on the PBS guide will help you weigh up that option.

PrEP is cheaper than ever before – however both importing and buying PrEP locally can be prohibitively expensive for some, especially those without access to Medicare. with this in mind, PAN offers free PrEP coupons for anyone unable to access PrEP at a price point within their budget. Check out how to apply for coupons at the Assistance Scheme page



If you decide to reduce or stop using condoms when you start PrEP you need to be aware of other STIs. But, even if you’re using condoms 100% of the time guess what… you need to be aware of STIs.


Condoms don’t protect against ALL STIs. Herpes, crabs, and other bugs can spread from person to person even if you’re using condoms – and using the consistently.

The STIs condoms can protect against don’t always do that either. If you enjoy oral sex you’ll probably never have used a condom or other barrier method when getting orally fixated.

Recent evidence also shows that gonorrhoea can be spread by smacking tonsils, so no matter what your chosen method of protection is – you’re bound to get an STI along the road at some stage.

PrEP users are required to test at least every three months in order to get a script fo their next batch of medication. Gay men in the wider community only test around 1.5 times a year.  This means PrEP users are picking up those STIs and getting treatment sooner, rather than passing on those STIs to their partners. Often a person with an STI won’t show symptoms – guys with Chlamydia only present with symptoms around 1/2 the time, and women even less. This is why regular testing is a crucial part of protecting your sexual health.



That’s up to you. Deciding to start PrEP is a personal decision for you, and in doing so you need to think about your own risk and be honest with yourself – sometimes that’s tricky in itself.

Different countries and states have different guidelines for who might want or need to consider PrEP. Some (but not all) of the things worth thinking about in making your decision...

Are you:

  • A man who has sex with men and doesn’t always use condoms (topping or bottoming).
  • Someone who has sex with men who have sex with other men.
  • The partner of an HIV-positive person who is not on treatment, or has a detectable viral load
  • Having regular receptive sex without a condom with people whose status you do not know (raw/bareback sex)

Have you had:

  • Rectal (in the butt) Gonorrhoea, rectal Chlamydia or infectious syphilis diagnosis during the last 3 months or at your last STI screening.
  • Any methamphetamine use within the last 3 months.
  • Any front hole (urethral) STI – if you’re a trans guy into guys
  • Any injecting drug use

We would encourage and recommend all trans and gender diverse people assess their risk and consult with a trans-friendly GP or sexual health clinic about their HIV prevention tools.


I'm Trans, Is PrEP for me?

PrEP is for all of us. It works for trans and gender diverse people too.

If you’re a person with a trans experience then it’s important to know your risk so you can make informed choices to protect your own sexual health – whether that is with condoms, TasP, PrEP or a combination. If you’re a HIV-negative trans person we would encourage you to consider PrEP. Globally, trans women who have sex with men shoulder a very heavy burden of HIV and trans men who have sex with other men are at the same risk as their cisgender gay brothers.

Truvada has no known contraindications with any transition-related hormones. It is an HIV medication that many trans people living with HIV have used for treatment over many years. You can check out any and all interactions with the drugs in Truvada at HIV using this great checker tool

Truvada as PrEP offers everyone full protection after 7 days of daily use – that’s for anal and front hole sex.

Our friends over at have developed a wonderful resource for gay, bi and queer trans men called GRUNT which is well worth a look into – and you can follow up on HIV treatment for trans men specifically there.

Need a trans-friendly GP? Contact your state AIDS Organisation for advice on where to get the care and support that’s right for you.


WHAT IF I’M a young person?

Until recently we didn't know much about how PrEP works for people under 18. Recently there was a study of people under 18 taking PrEP (called Study ATN113) which showed that PrEP offers similar protection in young people as those over 18 - and side effects were the same. The FDA in the US which regulates medicines recently updated how PrEP is to be administered to include young people because of this. As long as you're over 35kg you should be good to go.

The study did show that people under 18 were more likely to stop taking their PrEP after a while, so make sure if you're considering PrEP you're ready to take your pill every day! 

The current guidelines for doctors in Australia caution against people under 18 using PrEP - but that shouldn't be a barrier to you starting PrEP if you have a frank and honest conversation with your doctor, and you decide that PrEP is the best way for you to protect yourself.



First Nations people (Aboriginal and Torres Strait Island people) can access certain medications at reduced cost under the Closing The Gap scheme to improve health and wellbeing outcomes. If you are an ATSI person accessing PrEP on a clinical study where it would cost money to access the medication, it may be at reduced cost or even free.

Once PrEP is listed on the PBS this will mean that ATSI community members will likely be able to access further reduced cost PrEP to prevent HIV.

If you’re a prescriber – get up to speed on Closing The Gap