Pre-exposure Prophylaxis (PrEP)

Pre-exposure Prophylaxis (PrEP)

PrEP stands for pre-exposure prophylaxis. It is an HIV prevention method for people who do not have HIV, but are at risk. By taking a pill every day they can reduce their risk of becoming infected with HIV.

HIV is a virus that causes HIV infection, which damages the immune system and weakens your ability to fight infections and disease. The most advanced stage of HIV infection is AIDS. Read more about HIV and AIDS.

On this page you will find information on:

  1. What is PrEP? 
  2. Who would benefit from taking PrEP?
  3. How do I take PrEP? 
  4. Do I need blood tests?
  5. What are the side effects of PrEP?

What is PrEP?

PrEP is 2 medicines, tenofovir and emtricitabine, in a single tablet. These medicines help prevent HIV infection. When taken daily by people who do not have HIV, PrEP reduces the risk of HIV transmission by up to 99%. 

To be effective in preventing HIV, PrEP must be taken every day. This is because you need to have a baseline level of the medicine in your body constantly to prevent the HIV virus from establishing an infection. Missing doses can reduce how well it works. 

It is still advisable to use a condom. PrEP does not protect you against other sexually transmitted infections. 

PrEP is a publicly-funded medicine in NZ for those who meet certain criteria. It is available on prescription.  

Who would benefit from taking PrEP?

Some groups of people are at higher risk of getting HIV. For example, men who have sex with men, transgender people who have sex with men, and people who have a partner who is living with HIV (who is not taking HIV medication or has a detectable viral load). 

High levels of protection from HIV are achieved after PrEP has been taken daily for 7 days. To continue to be effective, it needs to be taken regularly each day. To find out if PrEP is right for you, talk to your doctor. You can also take the interactive quiz: Is PrEP right for me.

How do I take PrEP? 

  • PrEP is 2 medicines, tenofovir and emtricitabine in a single tablet.
  • Take 1 tablet once a day, at the same time each day. 
  • It is best taken with or just after food, or a meal.
  • If you forget to take your dose at the correct time, take it as soon as you remember. But, if more than 12 hours have passed since your last dose, skip the missed dose and take your next dose at the normal time. 

Do I need blood tests?

Before starting PrEP, you will need to get yourself tested to make sure that you are HIV negative. If you use PrEP when you are already living with HIV, it can cause the virus to develop resistance and reduce your options for HIV treatment.

Once you're on PrEP, you will need to be tested for HIV every 3 months. This is to ensure that PrEP is still protecting you. 

Your doctor will also do blood tests to check that your kidneys are working well. 

What are the side effects of PrEP?

Like all medicines, PrEP can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine. Common side effects include low energy, feeling tired, strange dreams or trouble sleeping, runny poos (diarrhoea) and nausea (feeling sick). Talk to your doctor if these things happen to you while you are taking PrEP because some of these symptoms are similar to HIV.

Learn more

PrEP-ing you with the basics Ending HIV
Pre-exposure prophylaxis (PrEP) New Zealand AIDS Foundation


  1. PrEP information for clinicians New Zealand AIDS Foundation
  2. Australasian Society for HIV, viral hepatitis and sexual health medicine HIV pre-exposure prophylaxis: clinical guidelines 2019
Credits: Sandra Ponen, pharmacist. Reviewed By: Angela Lambie, Pharmacist, Auckland Last reviewed: 07 Jun 2018