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nPEP Vs PrEP With Low Risk Exposure?

Sep 24, 2017

If in a long distance sexual relationship with a positive partner, We only engage sexually 2-3 year. factoring in cost of PrEP and rate of my risk would it ever be advised I skip PrEP and use nPEP after weekends with my partner. I know about upcoming studies on PrEP on demand and look forward to learning more.

Response from Mr. Jacobs

It sounds like you and your partner are figuring out options to maintain a healthy and pleasurable sex life on those 2-3 occasions per year. Cheers to you both for being interested and willing to explore these choices.

What you didn't share here are your actual risk factors. Not all sexual activities carry equal risk for each partner. For example, detectable levels of HIV could be more easily transmitted during receptive anal sex than insertive anal sex or even receptive vaginal sex. So I'm going to do my best at answering your question, with the caveat that I don't know what you are considering "risk."

Let's start with the first point: If your partner has an undetectable viral load for six months or longer, then they are physically unable to transmit the virus to others (; There is a lot of conversation happening now about whether or not it is even medically recommended for an HIV negative partner to use PrEP for HIV prevention when they are only with a HIV+ partner with an undetectable viral load for six months or longer.

Now, you mention that you've heard of "on demand" PrEP and wonder about how that works. In fact, that is a very common regimen that is prescribed outside of the U.S., especially if someone is not regularly sexually active, or may only be at risk of being exposed to detectable levels of HIV, a few times a year. The "Ipergay" data has revealed a lot about how well PrEP works when it is used as prescribed on an event-needed basis. (

Keep in mind, however, that the on-demand dosing regimen has ONLY been tested in cisgender men who have anal sex. It has not been tested in any individuals with vaginas. This is important to note because PrEP is believed to build up differently in vaginal tissues and likely needs more concentrations of the drug to offer adequate protection. So if you're asking about the practicalities of on-demand dosing for vaginal sex, I'm afraid we simply don't have adequate data.

It seems to me, than an on-demand dosing schedule for rectal sex would be much easier to take (and probably more cost-effective) than seeking out nPeP 2-3x a year. Depending on where you are, nPeP can often cost someone a pretty penny and the side effects can be challenging. It is not generally considered a more cost-effective nor easier solution.

But if you are able to get a bottle of 30 pills of Truvada, or its generic equivalent, and only use it during those 2-3 encounters per year, then it seems that could solve the problem right there. If you are in the U.S. you can contact the Advancing Access program about obtaining Truvada for free or low cost ( If you're outside the U.S., you may find ways of legally importing generic PrEP for very little cost at:

For more information about PrEP, access, and different regimens, please join the International Facebook "PrEP Facts" group at:

Unprotected sex with a HIV positive woman with a viral load of 700,000?
Risk When Condom Breaks With Guy On PrEP ?

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