How PrEP works
Taking PrEP before being exposed to HIV means there’s enough drug inside you to block HIV if it gets into your body.
The medication used for PrEP is a tablet which contains tenofovir and emtricitabine (drugs commonly used to treat HIV). It is sometimes called Truvada but most of the PrEP we use in the UK is generic PrEP.
In the US a second pill has been approved for use as PrEP – the branded drug Descovy or its generic equivalent.
Different PrEP delivery methods such as injectables and implants are being researched. As well as PrEP tablets, PrEP vaginal rings will be available soon.
Where to get PrEP
PrEP is now available free on the NHS in England from sexual health clinics.
Initially, PrEP was made available to 10,000 people in England as part of the IMPACT trial, which ended in July 2020.
In Scotland, PrEP is available through sexual health clinics. Visit the PrEPScot website to find out more information about how to access it.
In Wales, PrEP is available through sexual health clinics. For more information, see the Public Health Wales website.
All GUM clinics in Northern Ireland will be offering initial consultation and assessment appointments for a pilot trial, based at a centralised service in Belfast. This project will run for 2 years. There is currently no cap on numbers.
In clinical trials PrEP has been used in two different ways:
- taken regularly (one tablet per day).
- only taken when needed (two tablets two to 24 hours before sex, one tablet 24 hours after sex and a further tablet 48 hours after sex).
This second method is often called ‘on-demand’ or ‘event-based’ dosing.
Both methods have been shown to be very effective, although on-demand dosing has only been studied in gay and bisexual men.
Daily dosing is recommended for women who need to take PrEP every day for seven days to be protected against HIV.
Daily PrEP is recommended for all trans people using hormone treatment as there isn’t sufficient data to support other dosing options.
Taking PrEP safely
If you’re thinking about getting PrEP from outside the NHS, it’s important that you talk to an adviser from a sexual health clinic. They will support you to use the treatment safely and provide necessary tests.
In most big PrEP studies, no one became infected if they took PrEP as recommended. But if you don't take it correctly, it may not work.
The drugs used in PrEP are the same drugs that are prescribed to thousands of people living with HIV every year. They’re very safe and serious side effects are very rare.
A few people experience nausea, headaches or tiredness and, very rarely, the medication can affect kidney function. As a precaution, people taking PrEP have regular kidney function tests.
It’s important if you’re using PrEP that you go for regular STI screenings every three months.
If you like to speak to someone about PrEP, call THT Direct on 0808 802 1221.