Key Takeaways:
- On-demand PrEP (also called event-based PrEP or 2-1-1 PrEP) involves taking medication around the time of sex instead of daily
- The 2-1-1 schedule means 2 pills before sex, then 1 pill at 24 hours and another at 48 hours after the first dose
- Studies show it’s highly effective for cisgender men who have sex with men, but it’s not currently recommended for all populations
- Daily PrEP remains the gold standard for most people because it offers consistent protection and fits better with telehealth care models
If you’re exploring PrEP options, you’ve probably heard that you need to take a pill every single day. And for most people, that’s still the recommended approach. But what if you could take PrEP just around the times you’re having sex instead?
It sounds almost too good to be true, right? Well, there’s actually a version of PrEP called on-demand PrEP that works exactly like that. But before you switch up your routine, let’s talk about what it is, who it’s for, and why your healthcare provider might still recommend the daily version.
What Most People Know About PrEP
Traditional PrEP (pre-exposure prophylaxis) involves taking one pill every day to prevent HIV infection. When taken consistently, daily PrEP is incredibly effective at reducing your risk of getting HIV from sex by about 99%. It’s become a game-changer for people at higher risk of HIV exposure.
The daily approach works because it maintains protective levels of medication in your system all the time. Think of it like keeping your immune defenses up 24/7, ready for whatever comes your way.
But life isn’t always predictable, and some people don’t have sex frequently enough to justify taking a pill every single day. That’s where on-demand PrEP comes into the picture.
What Is On-Demand PrEP (2-1-1)?
On-demand PrEP, sometimes called event-based PrEP or 2-1-1 PrEP, is a different way of using the same medication. Instead of taking it daily, you take pills specifically timed around sexual activity.
Here’s how the 2-1-1 schedule works:
2 pills: Take these between 2 and 24 hours before you have sex (ideally closer to 2-24 hours before for best protection)
1 pill: Take this 24 hours after your first dose
1 pill: Take this final dose 48 hours after your first dose
So if you took your first two pills on Friday at 6 PM before going out, you’d take one pill on Saturday at 6 PM, and another on Sunday at 6 PM.
The concept came from a French study called IPERGAY, which showed this method could be really effective for certain groups of people. The medication builds up in your system quickly with that double dose and stays protective through the follow-up pills.
Who Is On-Demand PrEP Actually For?
Here’s where things get specific, and it’s important to pay attention. On-demand PrEP has been studied primarily in cisgender men who have sex with men. The research shows it works really well for this population when used correctly.
However, it’s not currently recommended for everyone. The Centers for Disease Control and Prevention (CDC) doesn’t recommend on-demand PrEP for:
- Cisgender women
- Transgender men
- Transgender women
- People who inject drugs
Why the limitation? It comes down to how the medication distributes in different body tissues. The studies that proved on-demand PrEP works focused on cisgender men, and the medication reaches protective levels in rectal tissue faster than in vaginal or frontal tissue. Without solid research proving it works equally well for other populations, healthcare providers stick with daily PrEP as the safer recommendation.
This doesn’t mean on-demand PrEP discriminates. It just means we need more research to know if it protects everyone equally well. Medical guidelines follow the evidence, and right now, the evidence supports on-demand PrEP mainly for cis men who have sex with men.
Is On-Demand PrEP as Effective as Daily PrEP?
For the people who can use it (again, primarily cisgender men who have sex with men), on-demand PrEP is very effective. The IPERGAY study showed it reduced HIV risk by about 86% when used correctly. That’s pretty impressive.
But there’s a catch: effectiveness depends heavily on two things.
Timing matters a lot. You need to plan ahead and take those first two pills at least 2 hours before sex (though 24 hours is even better). If sex happens spontaneously or you forget to plan ahead, you’re not protected. With daily PrEP, as long as you’re taking it consistently, you’re covered whenever sex happens.
Adherence is everything. You have to follow the schedule exactly. Miss that 24-hour or 48-hour follow-up dose, and you’re reducing your protection. It requires mental tracking and planning that some people find more difficult than just taking a pill at the same time every morning.
Infographic Content:
- Title: “Daily PrEP vs. On-Demand PrEP”
- Two columns comparing:
- Daily PrEP: | “99% effective with daily use” | “Works for all populations” | “No planning needed”
- On-Demand PrEP: | “86% effective with correct timing” | “Studied mainly in cis MSM” | “Requires advance planning”
For people with predictable, infrequent sexual activity, on-demand PrEP can work beautifully. But if you’re having sex regularly (more than twice a week), you’d probably end up taking almost as many pills as daily PrEP anyway, which defeats the purpose.
Why MISTR Currently Recommends Daily PrEP
At MISTR, we focus on daily PrEP for a few really good reasons.
First, daily PrEP provides the broadest protection for the most people. It works regardless of your gender identity, what type of sex you’re having, or how often you’re having it. You don’t need to predict when you’ll have sex or worry about planning ahead. You’re just protected, period.
Second, it’s honestly simpler to manage. Take one pill every day at roughly the same time. That’s it. No math, no calendar tracking, no “wait, when exactly did I take those first two pills?” moments. For most people, simpler means better adherence, and better adherence means better protection.
Third, our telehealth model is built around ongoing, consistent care. When you’re taking PrEP daily, we can monitor your health through regular check-ins and lab work. We can make sure everything’s working as it should and catch any issues early. This model of continuous care works best with daily medication.
That said, we’re not saying on-demand PrEP is wrong. For the right person in the right situation, it’s a legitimate option. But when we’re providing care remotely and want to make sure you’re getting the best possible protection, daily PrEP is the approach that serves most people most effectively.
What If I Want to Try On-Demand PrEP?
If you think on-demand PrEP might be right for you, the first step is having an honest conversation with a healthcare provider who understands HIV prevention. They can help you figure out if you’re a good candidate based on your specific situation.
You’ll want to consider:
- How often and how predictably you have sex
- Whether you’re in the group where on-demand PrEP has been proven effective
- Your ability to follow the 2-1-1 schedule consistently
- Whether you have sex spontaneously or with advance notice
Be really honest about your lifestyle and habits. There’s no judgment here. The goal is finding what actually works for your life, not what sounds good in theory.
Even if you start with on-demand PrEP, you might find daily PrEP makes more sense as your situation changes. Maybe your sexual activity becomes more frequent, or you discover you’re not great at remembering those follow-up doses. That’s totally fine. PrEP isn’t one-size-fits-all, and your approach can evolve.
The Bottom Line: You Have Options
Whether you take PrEP every day or use the on-demand approach, the most important thing is that you’re taking steps to protect yourself from HIV. Both methods work when used correctly by the right people.
Daily PrEP remains the gold standard because it offers consistent, reliable protection for everyone, regardless of gender identity or sexual patterns. It’s what MISTR specializes in, and it’s what we recommend for most people seeking HIV prevention through our platform.
But knowing your options empowers you to have better conversations with healthcare providers and make informed choices about your health. That’s what matters most.
Ready to get started with PrEP? At MISTR, we make it simple to get PrEP delivered to your door with ongoing telehealth support. Whether you’re just starting to explore your options or ready to begin daily PrEP, our team is here to help you find the approach that fits your life. Start your free consultation today and take control of your sexual health.
Frequently Asked Questions
1. Can I switch between daily PrEP and on-demand PrEP?
Technically yes, but it’s complicated and requires careful planning with your healthcare provider. You can’t just stop daily PrEP one day and start on-demand PrEP the next. There are specific protocols about timing to make sure you maintain protection during the transition. Always talk to your provider before making any changes to your PrEP routine.
2. How much does on-demand PrEP cost compared to daily PrEP?
The medication itself costs the same whether you’re using it daily or on-demand. However, you might use fewer pills over a month if you’re truly having infrequent sex, which could reduce costs. Most insurance plans and PrEP assistance programs cover PrEP the same way regardless of how you take it. The monitoring and lab work requirements are generally similar for both approaches.
3. What happens if I miss the 24-hour or 48-hour follow-up dose?
Missing follow-up doses reduces your protection, but you should still take the missed dose as soon as you remember (assuming you’re still within a reasonable timeframe). Then contact your healthcare provider for guidance. Don’t just skip it and assume you’re fine. The full four-pill course is important for maintaining protective medication levels.
4. Can I use on-demand PrEP if I’m in a relationship?
Absolutely. On-demand PrEP isn’t just for single people. If you’re in a relationship where you have infrequent, predictable sex, and you meet the criteria for on-demand use, it could work well for you. However, if you’re in a relationship where sexual activity is more frequent or spontaneous, daily PrEP would probably be easier and more protective.
5. Do I need a prescription for on-demand PrEP or can I just change how I take my daily PrEP?
Never change how you take your PrEP without talking to your healthcare provider first. While it’s the same medication, the dosing schedule is different, and switching incorrectly could leave you unprotected. Your provider needs to confirm you’re a good candidate for on-demand use and ensure you understand exactly how to take it properly.