A new study out of France has indicated that PrEP could be used as an on-demand “before and after” sex pill, instead of a daily medication as it is currently being used.

The results from the ongoing Prevenir observational study, have provided further evidence that so-called on-demand PrEP may be an effective strategy for preventing HIV infection in at-risk MSM (men who have sex with men).

The Prevenir research which used data from a group of 1628 at-risk, HIV-negative individuals, nearly all of them MSM, throughout the Paris region, showed that enrollment in the study, 44% of participants chose to use PrEP on a daily basis while 53% chose to use it on demand.


The on-demand PrEP group opted to take a double dose of PrEP (two pills) 24 hours before anticipated intercourse and then, (if sex did occur) took a further single dose 24 hours afterwards and a second dose 24 hours after that.

Jean-Michel Molina, of the University of Paris Diderot, explained that to date the study had found no HIV infections among men taking PrEP “on demand” or those taking it daily, meaning that PrEP could be used as and when required.

The first year preliminary findings of the ongoing three year study were presented by Molina at the International AIDS Conference in Amsterdam (AIDS 2018) last week.

Molina stressed that for the on-demand PrEP to work effectively the men have to take it as required, “it’s important to remember to take the pills both before and after sex.”

“After you’ve taken these dosages, you are good, you don’t have to worry about HIV,” He added.

While the Prevenir research is among other similar studies that are still very much in the early stages of research, Scientists are eager to see if the protection from daily vs on-demand PrEP remains the same over time and how its usage impacts people’s behaviour.

Researches say that it is important to note that these results do not apply to women, with studies showing that it takes considerably longer for PrEP (including with daily use) to build up in sufficiently protective quantities in the vagina as compared to the anus.