Sexual Health Services
in London and Surrey

Learn about PrEP

In this video, CNWL’s PrEP Lead answers some of the most frequently asked questions about PrEP.

Use the video's time bar to skip straight to the questions below:

  • What is PrEP? - 00:16
  • How does PrEP work? - 1:09
  • How effective is PrEP? - 1:17
  • Does PrEP have side effects? - 1:31
  • Does PrEP interact with other medications? - 1:50
  • How do you take PrEP? - 2:02
  • How do you start and stop PrEP? - 3:06
  • If you're taking PrEP, can you stop using condoms? - 3:33
  • Do you need to take PrEP if your partner is on it? - 3:47
  • What's the difference between PrEP and PEP? - 4:05
  • What if you forget to take your PrEP? - 4:38
  • Useful ways to integrate PrEP into your routine - 5:11

PrEP key facts

  1. PrEP is a medication taken by people who are HIV-negative to stop them contracting HIV. It is up to 99% effective when taken correctly.
  2. PrEP works by stopping the HIV virus from entering the cells in your body that it uses to reproduce itself.In this way, if you are taking PrEP correctly and you’re exposed to HIV, it can’t become established in you body. 
  3. PrEP is for anyone at increased risk of acquiring HIV. Examples of types of people who may be at increased risk of acquiring HIV include:
  • Gay, bisexual and other men who have sex with men
  • Trans women and non-binary people
  • If you or your partner/s come from countries with relatively high rates of HIV. You can find a list of countries considered to have high rates of HIV at the bottom of the page at this link.
  • Women and other people whose partner is a man who has sex with men
  • People who inject chems or party drugs, and share needles
  • Sex workers
  • People whose partner is HIV positive and are having condomless sex, unless their partner has been on HIV treatment for 6 months and their viral load is ‘undetectable’ (<200)

This list is not intended to cover everyone who can benefit from PrEP so if you are concerned you may be at increased risk of acquiring HIV and would like to discuss starting PrEP, please book an appointment following the instructions below.

  1. PrEP is flexible, and can be taken daily or as and when you need it (‘on demand’). Take PrEP daily to provide coverage against HIV anytime, anywhere; or you can take PrEP ‘on-demand’ (also called ‘event-based’ or ‘2-1-1’ dosing) if you know when you’re going to have sex. For more information about on-demand dosing, click here 
  2. PrEP only protects you against HIV.If you want to significantly reduce your risk of acquiring other sexually transmitted infections such as chlamydia, gonorrhoea, and syphilis, use condoms. PrEP can be used alongside condoms some or all of the time. For a wide selection of condoms at excellent prices, click here 

More information about PrEP is available via our Quick Guide to PrEP and the i-base ‘UK Guide to PrEP’. 

You can also read the Quick guide to PrEP leaflet in Spanish here and Portuguese here