04 February 26
Ending HIV
On-Demand PrEP FAQ
Have you got a question about on-demand PrEP? The good news is that we may have already answered it here!
Questions we answer:
- How effective is on-demand PrEP?
- How much does on-demand PrEP cost vs daily PrEP?
- Can transgender people take on-demand PrEP?
- Can cisgender women take on-demand PrEP?
- Do I need to take PrEP pills at the same time each day?
- Do I have to take my pills exactly two hours before sex?
- I took PrEP, but I didn’t wait the two hours before sex. What should I do?
- What if I forgot to take my follow-up dose?
- I took two pills but didn’t end up having sex, is that OK?
- What if I have sex multiple days in a row?
- If I don’t have enough PrEP pills to complete 2+1+1. Is it ok to use one less pill?
How effective is on-demand PrEP?
Good news – when taken correctly, on-demand PrEP is highly effective at preventing HIV, and you can expect the same protection you would get with daily PrEP.
How much does on-demand PrEP cost vs. daily?
One of the best parts of on-demand PrEP is its ability to save money! With on-demand PrEP, you only need to take your meds around the time you need protection.
So you can expect to save on the cost of medication by taking less over time.
For example. If you were taking Daily PrEP, assuming you purchased it at a pharmacy with Medicare, you would pay $25 for a one-month supply of 30 pills. On a calendar, it would look something like this:
Daily PrEP over a month
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
| 💊 | 💊 | 💊 | 💊 | 💊 | 💊🍆 | 💊 |
| 💊 | 💊🍆 | 💊 | 💊 | 💊 | 💊 | 💊 |
| 💊 | 💊 | 💊 | 💊🍆 | 💊 | 💊 | 💊 |
| 💊 | 💊 | 💊 | 💊 | 💊 | 💊 | 💊🍆 |
| 💊 | 💊 |
Key: 💊 = PrEP Pill | 🍆 = Sex
Each 💊 works out to $0.83, and 30 x 💊 = $25.
For a person taking on-demand PrEP, let’s say they only hook-up on the weekends over the same period.
Example of on-demand PrEP usage over a month
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
| 💊💊🍆 | 💊 | 💊 | ||||
| 💊💊🍆 | 💊 | |||||
| 💊 | 💊💊🍆 | 💊 | ||||
| 💊 | 💊💊🍆 | 💊 | 💊 | |||
Key: 💊 = PrEP Pill | 🍆 = Sex
In this example, the per 💊cost remains the same at $0.83; however, only 16 x 💊 were used, costing only $13.33.
Over the course of a week, in the above scenario, you’d be looking at this cost:
| Per Pill Cost | Per Week Cost | |
| Daily PrEP | $0.83 | $5.81 |
| On-demand PrEP (Using 4 pills throughout the week) |
$0.83 | $3.32 |
While you can’t buy fewer than 30 pills at a time, using a smaller number of pills, while following the 2-1-1 dosing, means you can save money by stretching your pill supply over a longer period!
Depending on how active you are, it may be possible to make 30 pills last two months if you budget your pills correctly. This would effectively lower the cost to half that of a person who’s taking PrEP daily, i.e. from $50 down to $25. Not too shabby! Just make sure you have enough pills to cover you before your next hook-up.
Can transgender people take on-demand PrEP?
On-demand PrEP is recommended for cis men and some trans people. Whether it’s an option depends on a number of things, such as the sex you were assigned at birth, if you’re on hormones and the types of sex you have.
For those who are interested, it’s best to discuss with your doctor (General Practitioner, or GP) to see if it’s right for you. You can check out this list of health care providers who are listed as providing gender affirming care on the transhub.org.au website.
Can cisgender women take on-demand PrEP?
Currently, on-demand PrEP is not recommended for cisgender women, though there may be an alternative event-based dosing strategy you can explore. We’d suggest speaking with your GP to learn what may be an option for you. Otherwise, daily or periodic PrEP remains a great option for cis women looking to reduce their risk of HIV transmission.
Do I need to take PrEP pills at the same time each day?
Ideally, yes. It’s important to try to time the follow-up doses to be as close to 24 and 48 hours after the initial 2 pills. Don’t stress if you don’t get it exactly right, but if you do end up forgetting for more than a couple of hours and you think you may be at risk, it may be worth speaking to a doctor. For example, if your initial dose was at 6pm on Monday night, it would look like this:
- 6pm Monday – 2 pills
- 6pm Tuesday – 1 pill
- 6pm Wednesday – 1pill.
Read: What to do if you missed a dose of PrEP
Do I have to take my pills exactly two hours before sex?
You need to take your first 2 pills at least two hours before sex, but you can take it more than two hours before, up to 24 hours before. This is so your body can absorb the medication and give you its full protective benefit.
If more than 24 hours have passed since you took your first 2 pills, you’ll need to take a 1 pill dose to maintain that protection.
I took PrEP, but I didn’t wait the two hours before having sex. What should I do?
It’s likely you wouldn’t have received the full protective benefits of PrEP, and there may have been some risk of HIV transmission.
At this stage, it’s important to speak with a medical practitioner, such as a doctor or sexual health nurse, to consider your next steps. In the meantime, keep taking your PrEP pills until you’ve had a chat, following the usual 2-1-1 dosing timing.
If you can’t get in to see your doctor soon, you can call the NSW Sexual Health InfoLink (1800 451 624) or the PEP Hotline (1800 737 669) to speak with a nurse sooner.
What if I forgot to take my follow-up dose?
Missing a follow-up dose by a few hours is OK. However, if you miss it altogether and you’ve had condomless sex in that time, then you should see a doctor or speak with a sexual health nurse as soon as you can.
I took the two pills but didn’t end up having sex, is that ok?
Absolutely! If you’ve taken your pills, but your sex didn’t end up happening, then there are no consequences on your health. You can either choose to stop taking your pills here, assuming no sex is going to be happening in the next 24 hours. Or you could take your single dose 24 hours after your initial double dose, to keep you protected if you think you’re having sex again soon.
What if I have sex multiple days in a row?
You can extend your on-demand dosing by continuing to take 1 pill daily until two days after the last time you hooked up.
Example of on-demand PrEP with sex over multiple days
| Mon | Tue | Wed | Thu | Fri | Sat | Sun |
| 💊💊🍆 | 💊🍆 | 💊🍆 | ||||
| 💊 | 💊 | |||||
Key: 💊 = PrEP Pill | 🍆 = Sex
If I don’t have enough PrEP pills to complete 2+1+1, is it ok to use one less pill?
If you don’t have enough PrEP to complete the 2+1+1, then you shouldn’t be relying on PrEP to prevent HIV. Taking less than the recommended doses puts you at risk of HIV transmission. So you should either wait till you can refill your script, or you can use condoms or rely on a partner’s undetectable status to prevent HIV.
We hope these answers have been helpful! If your question hasn’t been answered, drop us a line through our Instagram page or our FAQ tool.