Hopefully, by now, you know what PrEp is and what is does. We believe that it is one of the greatest game changers in HIV medical history. It is slowing down the progress of this virus within our community and literally saving countless numbers of gay males from a life living with HIV.

But, as great of a resource this medication is, there are some major issues that need to be considered. You, and only you, can decide if PrEP is right for you because it is a personal choice that is dependant upon your personality, ability to stick to a medication regime, follow-up for all needed doctors’ appointments as well as have the money or insurance to afford it in the first place.

Because of many of these challenges, there is a growing group of guys that don’t believe PrEP is right for them. But, this is also because they have not been informed about PrEP on Demand Dosing.


It is NOT NEW!

The first thing that you need to know is that On Demand Dosing for PrEP is not a new thing. Researchers have been studying the amount of the medication needed for someone to remain HIV virus free for over six (6) years.

Developed by researchers from the University of North Carolina, the model estimates two standard doses per week of Truvada (or a daily standard dose of tenofovir) would be sufficient to prevent HIV replication in rectal tissue”.

In 2015 in Europe, whether through national programmes or in trials, people are more often than not being given the choice of taking pre-exposure prophylaxis (PrEP) daily or intermittently (“event-driven” or “on-demand” PrEP). The French national rollout programme offers this choice as does the one recently set up by Scotland. The large implementation study hopefully soon to start in England will offer this choice too.

How is it taken?

This dosing option is only suitable for anal sex, not vaginal or frontal sex.

If you’re using On Demand it’s really important not to miss any doses.

On Demand dosing is as effective as daily PrEP for anal sex.

If you know that you might have condomless sex 24 hours in advance:

  • take 2 pills 2 – 24 hours before sex
  • take 1 pill 24 hours later
  • take 1 more pill 24 hours after that

If you’re having sex for an extended period of time, perhaps over a few days or a weekend, continue to take a pill every 24 hours until you have 2 sex-free days. (This is an important thing to remember if you are going away for holiday or having “extended sex sessions” over a weekend)

For Example:

If you take a double dose on Thursday evening at 10pm, and then have sex Friday evening at 7pm and on Saturday evening at 7pm, you should take the single dose of PrEP Friday evening at 10pm, Saturday evening at 10pm and Sunday evening at 10pm.

The initial double dose ensures you have a good level of protection in your body, if you take it at least two hours in advance of sex. The longer you leave it, up to 24 hours, the better (one of the drugs hits maximum efficiency 24 hours after taking it).

The single doses every 24 hours afterwards ensures the protection is maintained at this effective level.

Can I do that every Friday – before the weekend?

If you start, stop, and then want to start a dosing cycle again within a seven-day period, you won’t need the double dose on the second cycle.

For example, you take a double dose at 4pm on a Friday. That night you have sex, and take a single dose the next evening at around 4pm. You have sex again Saturday night, and take further single doses at around 4pm Sunday and Monday.

You then stop taking PrEP on the Tuesday, Wednesday and Thursday, but on Friday, in preparation for more weekend sex, you take a new single dose a couple of hours beforehand and start the dosing cycle again.

  • This option is not recommended if you have an active hepatitis B infection. The drugs in PrEP also suppress the hepatitis B virus and so starting and stopping PrEP can cause viral flare-ups and liver inflammation.

What if I forget to take a pill?

If you forget a dose, take a pill as soon as you remember. You should still have some level of drug protection in your body (unless you forgot for more than a couple of days), and a further dose will help top up your protection.

If you miss the double dose before sex, take a double dose after sex and then continue daily.

Immediately consult with your local STI clinic or clinician if in doubt, or to ask if they recommend you take PEP (Post-Exposure Prophylaxis).

‘When you take the double dose, you’re basically getting a double shot,’ says Nutland.

‘What you’re doing by putting that double dose in your body 2-24 hours before sex is giving yourself enough protection. Also, if there’s one piece of key information I would urge you to get across it’s that the follow-on dosage – 24 hours later and 48 hours later – is really, really important.

Nutland says the IPERGAY study has influenced his own use of PrEP. However, other researchers point out IPERGAY was just one, moderately-sized study. Nutland thinks organizations such as the CDC will want more, larger studies to be taken before it changes its recommendation of taking PrEP daily.


We honestly cannot say why you don’t know about On Demand Dosing. As we stated before, it is so common in Europe that studies have been done to try to figure out why some guys prefer the traditional dosing vs. the On Demand Dosing.

It solves so many problems

Some of the complaints about PrEP include

  • cost
  • availability
  • medication compliance
  • side effects

PrEP on Demand Dosing addresses all of these issues. No more do guys have to remember to take a pill a day, even if they are not planning to have sex. This also brings down the overall cost of the medication, because it isn’t being used as often. It is much easier to remember to take PrEP if it is based on planned sexual behaviors, instead of “just in case” and this will also decrease the overall and long-term side effects because guys are taking less pills, less often.

New York City as a Leader

For a long time, the most common way to describe pre-exposure prophylaxis (PrEP) was that it is a daily pill taken to prevent acquiring HIV. But now, New York City is tackling what might be a barrier to PrEP uptake with its new on-demand PrEP initiative.”

“On-demand” PrEP has been tested in trials like IPERGAY and other recent studies and has been shown to be highly effective. To that end, and following the International Antiviral Society–USA and the San Francisco Department of Public Health releasing on-demand PrEP guidelines, New York City’s Department of Health and Mental Hygiene (DOHMH) has released its own guidelines to providers who need education on this new way to deliver this still relatively new HIV prevention intervention”.

In the above interview, Mathew Rodriguez from TheBodyPRO, spoke to Demetre Daskalakis, M.D., M.P.H., deputy commissioner for the Division of Disease Control of the DOHMH, about the guidelines and why it was time to introduce them in New York.

MR: Scientists have known about the efficacy of on-demand PrEP since the IPERGAY trial in 2014. What do you think has stopped on-demand PrEP from becoming a standard practice in U.S.-based PrEP care?

DD: There’s a couple of things. It’s not part of current CDC [Centers for Disease Control and Prevention] guidelines for PrEP, so that makes it hard for folks to adopt. The good news is that there are other guidelines that have come out that talk about on-demand PrEP. The International [Antiviral] Society–USA guidelines are the first example of domestic guidelines saying that this is an option. New York has been monitoring that closely. San Francisco has also released guidelines about using it this way. We wanted to make sure we support our providers and make sure folks in New York have more options. This is like contraceptive conversations. The more options people have, the more people buy in. We wanted to say that this is evidence based and safe — and providers don’t have to guess if they don’t know. We want to make sure they have guidance to do this right.

Traditional vs. On Demand Dosing

‘Event-based dosing is a good option for gay and bisexual men who know, accurately, when they’re going to have sex,’ says Matthew Hodson, Chief Executive of NAM in the UK.

‘It’s important to acknowledge that the only event-based dosing regimen that has been demonstrated to be effective is one where the user takes two pills on the day that they expect to have sex, then, if they do have sex, one pill on each of the following two days.

‘Adopting this regimen, the large-scale French IPERGAY study found the same level of effectiveness as the daily dosing UK PROUD study.”

‘Whether PrEP is taken daily or based on sexual activity, it’s vital to remain adherent. Testing of tissues in studies of event-based PrEP suggest that the two doses after sex are crucial to the success of the strategy.’

His view is also held by London’s 56 Dean Street – the busiest sexual health clinic in Europe.

‘The IPERGAY study of event-based or on-demand PrEP showed the same efficacy as the PROUD study of daily PrEP’.

Not for every guy

Life is full of choices and this is another one you will need to consider. Only you know your sex life, ability to take medications, finances and insurance. These are all just some of the considerations you need to account for when making this decision. The great thing is that it isn’t permanent. You can make one choice, then change your mind, and then back again if you want.

The most important take-away from this article is that you do have options when it comes to PrEP and you need to ask for them! Each city and even country will have different rules and guidlines so far, but this is changing. America is, ironically, the last ones to implement these changes, considering the medications are made IN THE USA.

Final Thoughts

The world of HIV prevention has come a very long way from just condoms and abstinence, but it means nothing if you don’t afford yourself of these methods. Get yourself educated and make the best decisions for your life as possible.

And go out and have some great sex!

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