Using PrEP daily
If your lifestyle carries regular HIV infection risks, a clinician might recommend taking PrEP once a day. This will mean you’re protected all the time.
Daily PrEP is for anyone that wants constant, effective protection from HIV. If you’re sexually active and your exposure to the virus is frequent or unpredictable, this is probably the best option for you. You can sometimes get PrEP on the NHS, but it involves an appointment at a specialist sexual health clinic rather than your GP.
Daily PrEP tablets can be taken with a glass of water. The two active ingredients, emtricitabine and tenofovir, are antiviral drugs and work together to stop HIV multiplying in your body.
By taking PrEP at the same time each day, you’re more likely to develop a schedule you know you’ll stick to. It also lowers the risk of you being infected if you find yourself in an unpredictable situation where you’re unsure about exposure to HIV. Keeping the tablets in a safe place close to hand or setting an alarm can get you in a proper routine that will make sure the medication is as effective as possible.
Using PrEP on-demand
Another way of taking PrEP is on-demand, which is sometimes called event-based-dosing (EBD). This is a more casual way of taking the medicine, and whether it’s right for you depends a lot on when you’re planning to have sex.
Possibly the most important thing to know about using PrEP this way is that it only offers protection for receptive anal sex. Taking the medication on-demand is equally as effective against contracting HIV, but if you’re planning on having vaginal (frontal) sex or are using injected drugs with someone who might have the virus, you’d need to be on a daily PrEP routine for full protection.
How the medication is taken on-demand differs from using it daily, too. For the drugs to work properly, you’ll need to follow a specific pattern.
- 24 hours before you know you’ll be having unprotected sex (or potentially becoming exposed to HIV), take 2 pills.
- Take another pill 24 hours later.
- After another 24 hours after that, take your last pill.
If it sounds like a lot to take in, the schedule can be remembered as 2-1-1.
The routine will again need to change slightly if you’re planning on having more than one ‘event’ that puts you at risk of exposure, such as a weekend or any situation where you might have sex on continuous days. In this event, you’ll need to carry on taking a PrEP tablet for each day that the activity continues for. After the last time you’ve had sex, you’ll take a tablet every 24 hours for two more days.
PrEP drugs can create problems if you’ve got an hepatitis B infection that is active. Tenofovir and emtricitabine also suppress that virus, so taking the tablets in a stop-start fashion can cause flare-ups that lead to liver complications. So if you have hepatitis B, talk to your clinician before taking PrEP this way.
Are there any other ways PrEP can be taken?
There are other ways PrEP is used that might be more appealing if you’re looking for flexibility.
Holiday PrEP — This method involves taking PrEP for a block of time, when your risk of HIV exposure is higher. It can be used for vaginal and anal sex. This might be a good option if condoms aren’t at your disposal, or you’re potentially going to be in a situation where drugs are being used. The pattern for taking your tablets would be 7-7-7: one tablet per day a week before the holiday, one per day for the week you’re sexually active, and one a day for a week after the last time you have sex.
4 pills a week, aka ‘the Ts and Ss’ — This method should only be used for anal sex (because that’s the way it's been tried and found to be effective). The name comes from the pattern you take the tablets: Tuesday, Thursday, Saturday and Sunday.
It’s important to know that the studies and clinical trials that measured how effective these methods are were done on fairly small populations. Our clinical team have looked at the research and are happy to prescribe PrEP in the ways described above because the benefits of preventing HIV infections outweigh the potential risks. It’s always best to be fully informed about your HIV risks so you have a clear picture of which tablet routine will give you the best protection.