HIV infects the body by replicating (making copies of itself). The anti-HIV drugs in PrEP stop the virus replicating in your body. If you are exposed to HIV, for example during sex without a condom, but have been taking PrEP correctly, there will be high enough levels of the drugs in your body to prevent HIV.
Pre-exposure prophylaxis (PrEP)
Pre-exposure prophylaxis (PrEP) is a course of HIV drugs taken by HIV-negative people to protect them against HIV infection.
Taking PrEP correctly will reduce your risk of getting HIV to almost zero, however it won’t protect you against other sexually transmitted infections (STIs). Condoms are still the best protection from these.
PrEP is not taken for life – it is only taken for short periods of time when you may be at risk of HIV infection.
PrEP is different from PEP (post-exposure prophylaxis), which is an emergency treatment for HIV taken after possible exposure to the virus.
- The basics
- In detail
How does PrEP prevent HIV?
How effective is PrEP?
Used correctly, PrEP is very effective and will reduce the risk of HIV infection to almost zero.
If I take PrEP, can I stop using condoms?
Who can take PrEP?
PrEP is for anyone who is HIV-negative and is recommended if you are at a higher risk of HIV.
PrEP may be a good option for you if:
your partner has HIV and does not have an undetectable viral load
you have sex with multiple partners and you don't always use condoms
you’re having sex with a new partner and are not sure what their HIV status is
you have sex for money, or receive gifts for sex
you’ve shared injecting equipment or have been in a treatment programme for injecting drug use.
PrEP can be used by anyone who is sexually active - men and women, both trans and cisgender, whether you are gay, bi or straight.
How long do I take it for?
People do not stay on PrEP for life. PrEP is normally taken for periods when a person is most at risk of HIV. This might be during specific relationships, after the break-up of a relationship while dating new people, when planning a holiday when you know you will be sexually active with new people, while dealing with drug use problems, or when trying to conceive and one of you is HIV positive.
While you’re taking PrEP, you should visit your healthcare professional for regular check-ups (at least every three months).
Does PrEP have any side effects?
Many people feel no side effects from PrEP, others might experience mild issues like nausea, vomiting, fatigue and dizziness, but these usually disappear within a week or two.
In rare cases PrEP can also affect kidney functions. This is why it's recommended that people on PrEP have regular health check-ups so that healthcare workers can monitor their health.
Talk to your healthcare provider if you experience side effects while taking PrEP.
Where can I get PrEP?
PrEP isn’t available everywhere but it is being rolled-out in more and more countries. Ask your healthcare provider if it’s available where you are.
Test your knowledge of PrEP
How do I take PrEP?
Before starting PrEP, you must take an HIV test. This is because if you already have HIV, taking PrEP can be damaging to your health as it can make HIV treatment less effective.
There are two ways to take PrEP. Talk to your healthcare provider about the best option for you.
One tablet per day
This is the most common way to take PrEP. It works best when you take PrEP at the same time each day. For PrEP to work you must not miss doses.
You will need to take PrEP for 7 days before you are protected. During this time you should continue to use condoms.
You should take PrEP every day for as long as you want protection.
Event-based (on-demand) where you take PrEP before and after planned sex
This option would work for you if you are able to plan for sex at least two hours in advance or you can delay having sex for at least two hours.
There are different types of event-based PrEP depending on your pattern of sexual activity, so make sure you talk this option through with a health professional.
Why do I need to test for HIV when I’m taking PrEP?
Taking PrEP while not knowing that you are HIV positive is bad for your health. PrEP provides a low dose of antiretroviral treatment (ART). With good adherence, this amount of ART is enough to stop you from getting HIV, but if you already have HIV, it could make you more likely to develop HIV drug resistance. This is where your ART stops working. Small amounts of ART are not enough to stop the virus from replicating. Instead, the HIV virus is able to change itself so that it can by-pass the effects of ART and create new copies of itself anyway.
Testing regularly while you take PrEP means that you will find out if you are HIV positive as soon as possible, so you can avoid developing HIV drug resistance. Taking PrEP as prescribed will prevent you from getting HIV.
Can I take PrEP if I want a baby?
Yes! PrEP does not stop you from getting pregnant and is safe for women to take during conception, pregnancy and breastfeeding. PrEP is one of the ways that couples with different HIV statuses can try for a baby safely.
If you want to have a baby, but think you're at high risk of getting HIV, then PrEP could be a good option for you. If mothers get HIV during pregnancy and breastfeeding, it puts their babies more at risk. This is because your viral load is especially high in the first few weeks after getting HIV. Taking PrEP protects both you and your baby, so you can stay HIV-negative throughout conception, pregnancy and breastfeeding.
What is injectable PrEP?
Injectable PrEP is a form of PrEP that can be injected by a trained healthcare worker. To get full protection from HIV you will need to have two injections one month apart followed by an injection every other month. Many people may find this easier than taking a daily pill.
Currently injectable PrEP is only available in the United States. But UNAIDS is calling for injectable PrEP to be made available across the world. It has urged the pharmaceutical companies behind injectable PrEP to share the formula with generic producers in low and middle-income countries.