PrEP stands for pre-exposure prophylaxis, which prevents HIV infection before exposure. It’s a pill you can take if you’re HIV-negative that can help to stop you getting HIV, if you take it in the right way and at the right times both before and after you have sex. Across the UK, PrEP is now available for free to everyone through the NHS.

PrEP provides protection from HIV, but it has no effect on other sexually transmitted infections (STIs) and it won’t stop you getting pregnant.

PrEP is also different to PEP, or post-exposure prophylaxis, which is a 28-day course of treatment that you can take if you think you’ve had unprotected sex with someone that is HIV-positive in the last three days (72 hours).

But what is PrEP?

PrEP is an anti-retroviral, meaning that it’s a pill that blocks the HIV virus from invading your body. PrEP is usually a blue pill which usually contains a mixture of two drugs called emtricitabine and tenofovir. It can be sold with a variety of names including Truvada and Descovy and it’s important to try and get PrEP from a reliable source.

How does PrEP work?

HIV affects your health because it causes the death of white blood cells, which are mostly found in your blood and help protect you from illnesses. When HIV gets into your blood it seeks out these cells and goes inside them. It can then hijack them to make more of itself which infect other cells and allow the infection to spread to other people.

To take over cells, HIV has to convert its genetic information, something called RNA, into DNA – just like the DNA already found inside all of your cells. It’s this new DNA that contains the instructions that allow HIV to take control.

HIV builds DNA out of building blocks that it finds within your cells. The drugs in PrEP, emtricitabine and tenofovir, look just like these building blocks. HIV can’t tell the difference and when it tries to use the drugs to make DNA, it gets stuck and can’t finish. Without DNA, HIV can’t take over and is eventually destroyed by your cells.

How can I get PrEP?

PrEP is widely available but you need to be HIV-negative for it to work. You also need to ask your sexual health clinic to check your kidney function before you start and keep getting it checked. There are different ways to take PrEP too, and they’re not all suitable for everyone, so seek expert advice before you start.

Find out where to get HIV tested on the NHS. Once you get started on PrEP, remember to download Preptrack for free.