All you need to know about PrEP
PrEP&PREJUDICE
What is PrEP?
PrEP stands for pre-exposure HIV prophylaxis. It’s a way of preventing HIV by taking medicines before sex.
PrEP is taken by someone who doesn’t have HIV, to prevent them from getting HIV.
PrEP is most commonly taken as a once-a-day-pill.
This is usually taken as a combination of two drugs in one pill – tenofovir disoproxil fumarate (TDF) and emtricitabine (FTC) (sometimes referred to by its original patented name of Truvada or as TDF/FTC). A second pill version of PrEP, using a slightly different formulation of drug - tenofovir alafenamide (TAF) and emtricitabine (FTC) - can also be used as PrEP. This is often referred to by its patented name of Descovy or as TAF/FTC. In the UK, a TDF/FTC version of PrEP is the one most commonly used by the NHS. Descovy (TAF/FTC) is usually available on the NHS only in special circumstances but has recently been recommended as the version of oral PrEP for people under 18 to use.
Although most people who take oral PrEP do so every day, trials have also shown that oral PrEP can work if taken less often, before and soon after sex. This non-daily way of taking PrEP - often called ‘event-based’ PrEP - isn’t recommended for everyone. Taking non-daily PrEP might be more popular for people who know in advance when they are going to have sex.
How does PrEP work?
If a person taking PrEP is exposed to the virus known as HIV, the PrEP drugs they have taken prevents HIV from entering their cells and from replicating. This stops HIV from establishing itself and stops the person taking PrEP from becoming infected with HIV. For PrEP to work, there needs to be high enough levels of drug in the blood to be protective against HIV. That's why taking PrEP properly is important.
But PrEP work?
Studies across the world have shown that PrEP is highly effective at preventing HIV. As more and more people globally take PrEP, we should be reassured that PrEP works!
New ways of taking PrEP are starting to be developed.
Not everyone wants to take PrEP as a pill. New methods offer choices about how to take PrEP.
-
Injectable PrEP
-
PrEP vaginal ring
-
Monthly oral PrEP pill
What do I need to do before starting PrEP?
Before starting PrEP it’s important to know for sure that you don’t have HIV.
PrEP should not be used by someone who already has HIV. A ‘4th generation’ HIV test is preferable – these tests are better at picking up recent HIV infection than older types of tests. Most HIV tests used in sexual health clinics will be 4th generation tests. Tests that give rapid test results are not as good at picking up recent HIV infection. So, if you're using a 'finger-prick' test at home, those that are sent away for processing are more accurate.
If a 4th generation HIV test comes back negative, PrEP can be started straight away. If any HIV risks have been taken in the four weeks before that HIV test, it’s a good idea to take another test four weeks later, in case the first HIV test did not detect recent HIV infection. If that test comes back as HIV positive, it’s strongly advised to stop PrEP and seek immediate advice and support from a sexual health or HIV clinic.
Recent UK PrEP guidelines say that people at highest risk of HIV should not delay starting PrEP while waiting for test results. PrEP can be started and whilst waiting for test results.
If someone has experienced recent flu-like symptoms, after an HIV risk, then it is important not to start PrEP. The symptoms could be of recent HIV infection and they should seek support and advice from a sexual health clinic.
Guidelines on HIV and STIs screenings apply for all sexually active people, regardless of whether PrEP is being used or not.
Full HIV and STI screens are a great idea for all people with an active sex life! In addition, it’s advisable for oral PrEP users to have a blood test every year to check kidney function. It’s also a good plan for sexually active people to check their vaccination status for Hepatitis A and B and to ask about the HPV (warts virus) and Mpox (monkeypox) vaccination.
Apart from an HIV test and a standard STI screen, the only additional tests that are needed before starting oral PrEP are kidney function tests and a test for Hepatitis B. This is needed because PrEP drugs are also active against Hepatitis B. People with Hepatitis B can still use PrEP but will need advice on the safest way to do it.
A very small number of people develop issues with their kidneys when they use oral PrEP. Kidney function tests spot any problems with the kidneys and will help work out if PrEP shouldn't be used at all, or should be stopped. These tests will also work out if there are any pre-existing kidney issues, unrelated to using PrEP.
PrEP does not interact with most other medicines.
✓ PrEP does not interact with alcohol or recreational drugs.
✓ It can be taken by people using hormonal contraceptives and most over-the-counter medicines.
✓ PrEP is safe for trans people taking hormones.
Tenofovir disoproxil fumarate (one of the drugs in Truvada and its generic formulations) may interact with other medicines associated with kidney problems. It is strongly advised to talk with a health practitioner before starting PrEP if someone has a long-term health condition or is using other medicines.
A useful website from Liverpool University allows anyone to look up interactions between PrEP and other medications: www.hiv-druginteractions.org
How do I use PrEP?
Most people who start PrEP don't continue to take it continually.
Lots of people start and stop and then re-start PrEP, over again. Our relationship status might change, we might stop having sex altogether for a while, or we might just decide it's time for a break.
Starting, stopping and restarting PrEP is fairly easy, but it's important to get it right!
Recent UK guidance has changed about how oral PrEP can be started and stopped. The guidance makes starting PrEP simpler for everyone. Because the guidance has changed this information might be different to how you’ve previously used PrEP.
To start PrEP
The new guidance says that anyone can start oral PrEP (either TDF/FTC or TAF/FTC) by taking TWO pills between 2 and 24 hours BEFORE sex (or before any possible exposure to HIV). They should then continue to take ONE pill every day until stopping PrEP.
To stop PrEP
If you are using oral PrEP for HIV prevention during receptive frontal/vaginal (including neovaginal) sex, then take a single dose of PrEP EVERY day for SEVEN sex-free days after the last sex event. It’s then safe to stop.
If you are using oral PrEP for HIV prevention for ANY other kind of sex, carry on taking PrEP for another two sex-free days. So, if you last had sex on Saturday, take PrEP on Sunday and Monday. It’s then safe to stop.
This UK guidance on stopping PrEP is new - so this information might be different to what you’ve previously done. You can find out more about why these changes have happened here, and why they might be different to guidance given in other parts of the world here.
If you were assigned male at birth, and you’re using feminising hormones, the advice for you might be a bit different.
To restart PrEP
If you’ve not had sex since stopping oral PrEP, then it’s OK to restart PrEP as usual. As with the starting PrEP information above, you can take a DOUBLE dose of PrEP (i.e. two tablets) 2 to 24 hours BEFORE sex. You can then continue with ONE dose a day until you’re ready to stop. It’s really important to take the AFTER sex doses, as well as the ones before sex!
If you’ve had sex SINCE stopping PrEP, and that sex involved a possible exposure to HIV, it’s strongly recommended to have an HIV test BEFORE or at the same time as re-starting PrEP.
Most people who take PrEP experience no side effects.
However, all medicines can have side-effects and those seen most commonly in people taking PrEP do not tend to last long.
Studies show that under one-in-ten people report short-term side effects when using oral PrEP. These can include feeling sick, stomach pain, dizziness and headache. These tend to be most common in the first month of using PrEP. For most people who experience these side effects, they last for a few days and almost always stop within a month.
If you're using PrEP and experiencing unpleasant side effects, then a health service will be able to provide you with advice on using over-the-counter or prescription medicine to help. A very small number of people end up stopping PrEP because of side effects.
A very small number of people with pre existing kidney problems might have additional issues when using Truvada (or its generic formulations). This is because one of the drugs in this formulation of PrEP is processed by the kidneys and can put additional strain on them. This is why kidney function tests are important for PrEP users.
PrEP use can lead to a very small reduction in the hardness of bones. This will not make a difference to people with normal bone density prior to using PrEP. The loss of bone density does not get worse with on-going PrEP use, and density returns to normal after stopping PrEP.
Some people decide to switch how they use PrEP to reduce the very small chances of side effects. For example, when it's possible - to change from daily dosing to non-daily dosing, or only taking PrEP during times of known risk (e.g. when going on holiday). Just because side-effects are uncommon does not make them unimportant: we need to support people who are experiencing side effects with information and support strategies.