Do I need to take PrEP every day?


Not sure about taking your PrEP every single day?

There are more ways to use PrEP than we knew about when we first discovered PrEP as an effective HIV prevention tool.

Daily PrEP

PrEP is an effective tool for most people wanting to remain HIV negative, and for the majority of people - taking a daily pill for round the clock protection is a simple and effective way to do that. Daily PrEP for most people is easy, and it’s what we are used to hearing about. A daily pill to prevent HIV. Just start up by taking the daily pill for a week to boost your protection, and then keep taking it every day.

On Demand PrEP

Daily PrEP isn’t the only way to take PrEP. Depending on who you are, the kind of sex you’re having, and how often (we’ll get into that a bit later on) you might be able to take PrEP during the times you need protection, and not worry about PrEP during other times.

How to use On Demand PrEP

As long as you have a bit of lead time, you can plan your protection just like you plan your hookup.

  • Take 2 PrEP pills between 2-24 hours before sex. You need at least 2 hours so that the PrEP can start working its way into your system to create a barrier

  • Have sex - this is the fun bit.

  • Take a single PrEP pill 24 hours after your first double dose

  • Take another single PrEP pill 24 hours after your last dose.

If you’ve just had sex over one short period, this is where you can stop taking PrEP. Pretty simple right? this is what it might look like.


Well, what if you have a big weekend of sex? No problem. You can just keep adding on an additional single PrEP pill day until you have two sex free days where you’ve taken PrEP. That might look like this:


Why use On Demand PrEP

There are some people who don’t need or want to use Daily PrEP? Let’s look at why that might be.

  • Being in a mostly monogamous relationship. Maybe you only sleep with each other most of the time, but sometimes you’ll open things up for a big party weekend, or when one partner is travelling. Do you need constant protection from PrEP? Not necessarily.

  • If your partner is HIV-positive with an undetectable viral load - you don’t need to take PrEP to protect yourself. Having sex with an undetectable person is the safest form of sex you can have regarding HIV risk. If you’re sleeping with other people besides that partner, you might want to look at taking PrEP during those times.

  • A very small group of people who start taking daily PrEP get short term side effects. This might be nausea, headaches, etc. For most of those people side effects settle down in week or so. There is a very small group of people for who side effects don’t seem to ease off. To minimise PrEP side effects just taking PrEP around times of risk might be an option.

  • There are some people who Daily PrEP isn’t suitable for because of some other conditions. If you have reduced kidney function, or you have concerns about your bone density (say you have a long history of osteoporosis in the family, and you’re 40+) taking a daily PrEP pill may impact your general health. You can reduce the impact on your bones and kidneys by taking PrEP ‘on demand’ or during times you need it most.

  • Don’t want to take a pill every day? PrEP is an incredible safe tool to use to prevent HIV. In fact, it’s a safe to take as a daily asprin. There are some people who Daily PrEP works for, but they have concerns about taking a medication every day. Depending on how often they are having sex, taking less PrEP might be what works for them.

  • Struggle to remember your PrEP every day? If you forget your PrEP regularly, your PrEP protection levels will drop. If you take your PrEP 4 or more days per week and your’re a cisgender man - you’ve got great protection. Less than that and you may still be at risk for HIV. If you can remember and plan to take your On Demand PrEP over a couple of days during periods you might be at risk - you don’t have to worry about forgetting the other times.

Does it work for everyone?

If you are a cisgender man, On Demand PrEP will work for you.

If you are a cisgender woman having vaginal/frontal sex On Demand PrEP doesn’t provide adequate protection against HIV. If there is HIV risk from anal sex only, On Demand PrEP may be suitable.

If you are a transgender man having vaginal/frontal sex On Demand PrEP doesn’t provide adequate protection against HIV. If there is HIV risk from anal sex only, On Demand PrEP may be suitable.

If You are a transgender woman On Demand PrEP may not provide adequate protection against HIV. Some hormones used by trans women can cause less of the PrEP drugs to be present in the body. We don’t know for sure what this means for how effective On Demand PrEP would be. Daily PrEP still works great for trans women. More research is also needed into the way PrEP drugs penetrate neovaginal tissue.

If you are a trans woman who does not use feminising hormones, and has not undergone bottom surgery you should have a conversation with your trans-friendly doctor to discuss whether On Demand PrEP is right for you.

If you have hepatitis B, On Demand PrEP will not be suitable. The drugs in PrEP can also be used to treat hepatitis B infection. If you stop and start taking the medication (like we do using On Demand PrEP) this can cause flare ups of the hepatitis B virus.

If you do not have hepatitis B, and you’re interested in On Demand PrEP - make sure you’re vaccinated against hep B and get boosters where required - chat to your doctor.

check out this great cheeky animated video on how to use PrEP on demand.

Michael Whelan