PrEP On-Demand

Less active? There’s a non-daily way some people take PrEP.

Couple Kissing - Get PrEP on-demand online through us

What is PrEP On-Demand?

When PrEP was first approved the manufacturer advised for it to be taken once daily. For many people this makes a lot of sense – especially if risks are more frequent and/or less predictable.

However, since PrEP has been available studies have been done to look at another way to take it. PrEP On-Demand is taking two tablets 2-24 hours before a sexual risk and continuing once daily for 48 hours after. This is event-based PrEP taken just around the time of a risk. (Often referred to as the 2-1-1 method).

How to take PrEP On-Demand


PrEP Dosing Guide - Take 2 pills 2-24 hours before sexual activity

2 tablets 2-24 hours before sexual risk.


PrEP Dosing Guide - take 2 pills 48 hours after sexual activity.

1 tablet the day after.


PrEP Dosing Guide - take 2 pills 48 hours after sexual activity.

1 more tablet the following day.

Always speak to your care provider before switching how you take medication to ensure it will work for you.

PrEP On-Demand Effectiveness

We know taking once-daily PrEP can reduce the risk from sexual activity by up to 99%. Earlier studies for On-Demand use showed it could reduce the risk by 86% – however – more recent data suggests it may be as effective as once daily use.

Most patients with our clinic go the once daily route, but some choose to use On-Demand. Some people may also switch between daily or On-Demand use depending on changes in their lifestyle.

Who Should Take PrEP On-Demand?

On-Demand is not recommended in people who do not plan their sexual activity in advance or are having more frequent risks. If the loading dose of two tablets are missed a person may need emergency PEP. If someone is being sexually active at least once a week, they will almost be taking the pill daily already so On-Demand is probably not the best fit.

On-Demand use is not appropriate for use in cis women or trans men (we don’t have evidence to know if it will be effective) or for HIV protection unrelated to sex. It also can not be used this way with Descovy (the newer formulation of PrEP) at this time.

How you take PrEP is very individualized. Always make sure to speak with the healthcare provider prescribing your medication before taking PrEP differently than how it was prescribed.

– Drew & Joaquin, PrEP Clinic Pharmacists

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