PrEP (pre-exposure prophylaxis)

What is PrEP (pre-exposure prophylaxis)?

PrEP (pre-exposure prophylaxis) is a tablet that reduces the risk of becoming infected with human immunodeficiency virus (HIV). Each PrEP tablet contains two antiretroviral medications – tenofovir and emtricitabine.

PrEP can be taken by people who are HIV-negative (do not have HIV) and at risk of HIV exposure. For example – men who have sex with men (MSM) and do not use condoms, people who have a sexual partner who has HIV and is not on treatment and people who inject drugs.

People of all genders, sexualities and bodies may be eligible for PrEP.

How does PrEP work?

The anti-retroviral medications (tenofovir and emtricitabine) in PrEP work by helping fight HIV infection and by preventing HIV cells from replicating (making copies of itself). PrEP is not a cure for HIV, but it does help to prevent HIV transmission.

How effective is PrEP?

If used correctly PrEP can be over 99% effective at preventing HIV transmission.

Before starting PrEP

Before starting PrEP, you will need to see a doctor or nurse.

The doctor or nurse usually takes a medical, sexual and drug-use history. This will access you risk and eligibility for PrEP and guide other recommended tests and healthcare. You will have the opportunity to ask questions and be given any information you may need. What you discuss will be kept confidential.

  • If you have had a recent risk of HIV exposure (within 72 hours) you may need post-exposure prophylaxis (PEP) before starting PrEP. PEP is a 28 day course of antiretroviral tablets that may prevent HIV infection. For more information, you can talk to your doctor or nurse or see: GET PEP.

Before starting PrEP, you will need a negative HIV blood test indicating you do not have HIV. Your doctor or nurse will also take blood tests to check:

Other tests you may need before starting PrEP include:

Where can I get PrEP?

You can book an appointment with us at our Melbourne clinics.

Any general practitioner (GP) and authorised nurse practitioners can provide a script for PrEP which you can take to a pharmacy, who will give you the tablets. You will usually be given tablets for 90 days. With a Medicare card, a month’s supply of PrEP will cost around $40 or $6.50 if you have a concession card.

If you do not have a Medicare card or the cost of PrEP in Australia is too high, then another option is to purchase a generic version of the drug online from a reliable overseas supplier. Purchasing a month’s supply of PrEP online will cost around $20 a month. You will still need to see your doctor or nurse for a script before ordering online.

To get a script for PrEP from Sexual Health Victoria, see our clinics or book an appointment online.

To order PrEP online, visit the PrEP Access Now.

How do I use PrEP?

It is recommended you start PrEP within 7 days of your negative HIV blood test being taken.

It is recommended all people at risk of HIV take PrEP by swallowing 1 tablet daily at approximately the same time each day. Cisgender men who have sex with men (MSM) may be able to take PrEP on-demand. This means taking 2 tablets together 2 – 24 hours before you have sex, 1 tablet the next day (24 hours after the first dose) and then another 1 tablet the following day (48 hours after the first dose). For more information, you can talk to your doctor or nurse.

When does it start to be effective?

When you start PrEP (for the first time or after a break) it can take up to 7 days to start working to prevent HIV.

After starting PrEP

After starting PrEP, you will need to see your doctor or nurse every 3 months for follow-up care including a blood test for HIV. Blood tests to assess kidney function should be taken at 3 months and then if within normal limits, every 6 months.

Are there any side effects of taking PrEP?

Possible side effects for a small number of PrEP users include gastrointestinal symptoms (flatulence, diarrhoea, nausea), headaches and sleep disturbances.

These side effects are usually mild and settle with time.

Gastrointestinal symptoms may be less likely if PrEP tablets are taken with a meal.

In rare cases, PrEP users may develop a minor reduction in kidney function and bone density.

What if I miss my dose?

  • Take the missed tablet as soon as you notice.
  • Continue to take your tablets as normal.
  • If you miss a tablet for one day, there is no need to take 2 tablets the next day.
  • If you miss multiple PrEP tablets you may be at risk of HIV – particularly if it is in the first weeks of you taking PrEP. It is recommended you speak to your doctor or nurse for support and information. You may choose to abstain from sex or use condoms until you seek health information.
  • If you have had a recent high-risk HIV exposure (within 72 hours) and missed PrEP around the time you had a recent high-risk HIV exposure (within 72 hours) and missed PrEP around the time that the high-risk exposure occurred you may need post-exposure prophylaxis (PEP). For more information you can talk to your doctor or nurse or see GET PEP.

What if I want to stop taking PrEP?

The current evidence suggests that cisgender men who have sex with men (MSM) who take either daily or on-demand PrEP can safely stop by taking a dose (1 tablet) of PrEP at 24 and 48 hours after their last HIV risk exposure.

For all other people who take daily PrEP, it can be stopped 28 days after the last HIV risk exposure.

If you want to start taking PrEP again after a break, you will first need to repeat blood tests for HIV and kidney function.

Will PrEP affect my pregnancy or breastfeeding?

The current evidence suggests PrEP can be used safely during natural attempts to conceive, pregnancy and breastfeeding.

What else should I know about PrEP?

What are some other ways I can lower my risk of getting sexually transmissible infections (STIs) and blood borne viruses (BBVs)?

You can lower your risk of getting STIs and BBVs by using barrier protection (external condoms, internal condoms or dental dams), correctly during any type of sex (vaginal, anal or oral sex) and when sharing sex toys.

Barrier protection is not 100% effective at preventing STIs and BBVs.

You can also lower your risk of getting a BBV by:

If your sexual partner/s and/or injecting equipment sharing partner/s are living with HIV you can talk to them about treatment as prevention (TASP). This means taking antiretroviral tablets to prevent passing on HIV. For more information you can talk to your doctor or nurse.

You can also lower your risk of getting an STI or BBV by both you and your sexual partner/s and/or injecting equipment sharing partner/s having regular STI and BBV testing. For more information on testing at Sexual Health Victoria see our clinics or you can book an appointment online.

Where to get more information and support

If you are using the internet for information, only use reliable and reputable websites. Be aware of websites containing inaccurate and harmful information and imagery.

  • Sexual Health Victoria
  • Better Health Channel – a safe and friendly General Practice, providing care for LGBTI community members as well as specialist medical care for people living with HIV and expert sexual health screening and treatment.
  • Ending HIV – for information on STI and HIV testing, treatment and staying safe.
  • Equinox – for transgender services.
  • Headspace – for young people.
  • Melbourne Sexual Health Centre – a specialist sexual health clinic.
  • Minus 18 – for young lesbian, gay, bi-sexual, transgender and intersex (LGBTI) people.
  • Multicultural Centre for Women’s Health – for culturally and linguistically diverse women.
  • PAN (PrEPaccessNOW) – a community-driven HIV prevention not-for-profit organisation advocating for equal and affordable PrEP access Australia wide.
  • PrEP'D For Change – a volunteer organisation providing PrEP information and support for everyone in Australia
  • PRONTO! – a peer-led service helping men who have sex with men.
  • TouchBase – information, support and services for LGBTI people.
  • 1800 My Options phone line 1800 696 784 or website
  • A doctor or nurse.
  • Your local community health service.


This website and any related materials are for general information purposes only and should not be relied on as (or in substitution for) medical or other professional advice. You should seek specific medical or professional advice for your individual circumstances.

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Last updated: 2 May 2021