Is on-demand PrEP too demanding? Australian men’s experiences


While on-demand PrEP offers a welcome alternative to daily PrEP for Australian gay and bisexual men, some found that it led to a lack of sexual spontaneity and increased anxiety, according to a qualitative study published in Sociology of Health and Illness.

Men needed to establish PrEP routines through planning and experimentation to make it work for them and to integrate it into their sexual and daily lives.  


In 2019, clinical guidelines in Australia changed to acknowledge that, in addition to daily PrEP, on-demand PrEP could work as an alternative for cisgender gay and bisexual men. However, clinicians have been apprehensive about recommending this alternative, partly arising from fears that adherence would be more complicated.

On-demand or event-driven PrEP is also known as 2-1-1. It works by taking two pills two to 24 hours before sex, another pill 24 hours after the first dose and the last pill another 24 hours later, or 48 hours after the first dose. While this alternative allows men the freedom not to have to take daily PrEP, it means that they need to plan around sex and ensure that the doses are taken at the right times. Among Australian PrEP users, this approach has grown in popularity, from 5% using it in this way in 2019 to 20% doing so in 2021.


on demand

In relation to pre-exposure prophylaxis (PrEP), on-demand dosing is an alternative term for event-based dosing. See ‘event based’.


A feeling of unease, such as worry or fear, which can be mild or severe. Anxiety disorders are conditions in which anxiety dominates a person’s life or is experienced in particular situations.

CAT scan

A computerised axial tomography (CAT) or computed tomography (CT) scan is a type of specialised X-ray that gives a view of a 'slice' through the body, and is used to help detect tumours, infections and other changes in anatomy.


Bone disease characterised by a decrease in bone mineral density and bone mass, resulting in an increased risk of fracture (a broken bone).


In relation to pre-exposure prophylaxis (PrEP), 2-1-1 dosing (and 2+1+1 dosing) are alternative terms for event-based dosing. 

Currently, the only recommended dosing choices for gay and bisexual men using oral PrEP are daily  and on-demand dosing. However, some men also use PrEP periodically – during periods when they might be exposed to HIV, such as during festivals or when on holiday. In these instances, men take PrEP for the duration of the heightened risk period, akin to daily PrEP. Other dosing schedules, such as taking PrEP four days of the week, are not currently recommended, despite evidence showing similar levels of protection to daily PrEP. In Australia, PrEP can either be accessed at a reduced cost through the national health system, privately at a higher cost, or imported through online sources.

While it is evident that men take PrEP in different ways, little is known about how men incorporate different dosing patterns into their everyday lives, including the challenges involved in ensuring that they get the necessary protective dose, and that the act of taking it does not become overly disruptive to their sex lives or more generally.

The study

Dr Anthony Smith from the University of New South Wales interviewed 40 PrEP users with non-typical PrEP patterns in 2022. Thus, the men were either taking non-daily PrEP, or had paused, changed, or stopped taking PrEP in the past year.

Most men were born in Australia (70%), lived in Victoria (43%) or New South Wales (35%), identified as gay (75%) and all were assigned male at birth. Men ranged in age from 21 to 77, with most men either in their 20s or 30s.

Less than half the men used on-demand PrEP (45%), while some took daily PrEP (25%), used a blend of strategies or periodic PrEP (13%) and some had stopped taking it (17%).

PrEP routines

Participants described routines that assisted with PrEP adherence, regardless of dosing schedule. This included various reminders – alarms, post-it notes, leaving pills in a specific spot, using pill boxes, a partner’s prompt, or daily domestic duties – that signalled that it was time to take the dose. Kyle, who took daily PrEP, described it in this way:

“My routine is normally: get up, feed the cat that’s meowing, and then I take my PrEP. That’s what I still do now. It’s just that if the cat was not, for some peculiar reason, awake, and I didn’t feed the cat, then I’d forget to take my PrEP.”

Thus, this form of adherence was subject to fluctuations in the environment, and in some cases, routines had to be specifically changed to incorporate the practice of pill taking. RJ, who had stopped taking daily PrEP, spoke about preferring partners not to stay the night, as this could potentially disrupt his PrEP routine:

“I was terrified. I’m like, ‘This cannot happen again,’ to the point that I remember kicking out people before I get to sleep, so I can wake up at seven to take my pill. I don’t do overnights.”

Some participants spoke of the challenges remembering if a pill had been taken or not, which could lead to inadvertent double dosing. Blister packs were often helpful in this regard.

One participant had to anticipate his boyfriend’s routines to take PrEP that was covertly stored in a spare room – he was taking it without his boyfriend’s knowledge for protection during secret hook-ups. Another participant spoke about trying to “find a flow” with taking PrEP. He lived in rural area and switched to on-demand PrEP, as he only needed it for weekend trips to the city, and did not want to take unnecessary daily pills.

For some younger participants, this was the first time they had to take a medication regularly. Establishing a routine was more challenging than for those used to taking other medications regularly.

PrEP planning

Participants contrasted on-demand dosing with daily PrEP. While it meant that overall pill burden could be reduced, and did not necessitate a daily routine, it required active planning in anticipation of sex. For some, like Ciaran and his partner, this amounted to excitement, as they only used on-demand PrEP when they were planning sex with a third partner:

“It’s like ‘hey, we’ve decided we are going to have this guy over and we are going to do this, yay, let’s take PrEP’. It’s like an advent calendar [laughter]—that’s such an inappropriate analogy—but it’s like ‘this is day 1, this is day 2, let’s fuck’ and a couple of days after, you keep going [with PrEP]. So, to me it’s actually part of the build up of ‘we get to do that this weekend’.”

However, more often, on-demand PrEP was viewed as interfering with spontaneous sex and took up mental energy. Dakota switched back to daily PrEP once their finances improved. While on-demand PrEP was cheaper, they stated that: “I just don’t really want to have to think about that, I’ve got too much other stuff going on.”

Some participants also spoke of strategies that were required for spontaneous sex, to adhere to the two-hour minimum rule before sex. They would pretend to be late for a hook-up, watch a movie before sex, or delay anal penetration by performing other sexual acts. This contrasted with daily dosing, which was not framed as disruptive to sex.

Predicting when sex would happen and timing the on-demand dose accordingly caused some participants frustration, due to the “guess work” required. For Jason, it caused anxiety that he compared to using condoms – a type of anxiety that he did not experience with daily dosing:

“For the next 24, 48 hours, it’s kind of there stuck in my mind: ‘You must take this pill! You must take this pill!’ And in a way, it kind of goes back to how condoms used to be intrusive. It’s sort of re-established a bit of that idea of HIV prevention being intrusive instead of very much a passive thing that is going on in the background.”

He also spoke of “wasting” pills on hook-ups that were unsatisfactory, and how the subsequent doses would work as a reminder: “I kind of think, I just wish I hadn’t bothered. […] I’ve used these PrEP pills for a hook-up that just didn’t feel worth it.”

PrEP experimentation

While most participants said that PrEP did not affect them in any noticeable way, others did not experience it in this way. Several men spoke about the lengths they had to go to in order to avoid unpleasant side effects, such as Jason who switched to on-demand PrEP to avoid side effects:

“If I start taking it, I feel sluggish. My stomach feels a bit crap. And if I take it before I sleep, I get such vivid dreams, like incredibly vivid dreams that I hate… I guess as well that’s part of the reason why I’m not taking it daily, because I kind of feel I don’t really want to take it unless I have to, because it mostly just leaves my digestive system feeling ravaged.”

Men described experimentation with different ways to take the pills so as to minimise side effects, ensure the correct protective dose (or what the participant felt was sufficient) and to enjoy sex. For example, men experimented with taking PrEP with and without food, or by starting a course of on-demand PrEP a few days early so that they didn’t have side effects when they had sex.

Men mostly experienced loose bowel movements, nausea, and an upset stomach. In some instances, men who were usually the bottom partner would top instead to work around these side effects.

One participant with lactose intolerance struggled because of the lactose present in PrEP pills and needed to experiment to find taking PrEP in a way that worked best for him. Another had osteoporosis, and expressed fears regarding how PrEP might affect his bones. Despite his doctor’s recommendation to stop PrEP, he values and enjoys condomless sex and decided to try taking PrEP every second day, taking breaks, and using on-demand PrEP instead.


On-demand PrEP offers an attractive alternative for some gay men in that it requires fewer pills, costs less and offers a degree of flexibility not offered by daily PrEP. However, this can come with increased planning demands, a lack of spontaneity and increased anxiety. The authors also highlight the fact that ‘adherence’ is not always a straightforward notion. While it is often framed as a matter of a person diligently sticking to a dosing regimen – and lack of adherence may be viewed as a personal shortcoming – it is usually much more complicated when integrated into an individual’s life.

Men in this study found multiple mundane ways to make PrEP work for them: the findings highlight both successful daily navigation and the challenges involved that can lead to a lack of adherence. While many gay men may start taking PrEP, not all persist in taking it, so these practical aspects of PrEP taking are important to consider. Additionally, these findings can inform conversations between healthcare providers and patients, especially those struggling with adherence or integrating on-demand PrEP into their lives.


Smith AKJ et al. Dosing practices made mundane: Enacting HIV pre-exposure prophylaxis adherence in domestic routines. Sociology of Health and Illness, online ahead of print, 12 June 2023 (open access).

DOI: 10.1111/1467-9566.13687

Smith AKJ. Making PrEP work: understanding drug adherence as a domestic practice. Kirby Institute Seminar Series, 30 May 2023.