[Question #8068] HIV -Prep and oral sex

49 months ago

I am a gay male who is a long term non-monogamous relationship. I have infrequent (4-6 x/yr) sex outside my primary relationship (usually involves mutual masturbation and oral sex -primarily receiving, but sometimes giving. No anal intercourse outside the primary relationship). I have a hx of being anxious after performing oral sex on someone. My pcp started me on prep (Descovey) two years ago (mostly due to periodic episodes of being worried after performing oral sex on someone). I have taken it daily for the past two years. A few days ago I performed oral sex on two guys. They did not cum in my mouth. I did have a small ulcer at the time that was healing. I do worry a bit about prep failure.

Questions:

-Your thoughts on risk (oral sex while on prep with small ulcer)

-Is prep failure as rare as what I see (mostly due to poor med compliance and/or rare hiv strains that are not susceptible to the drugs in prep)

-Other thoughts?

Thanks so much

Edward W. Hook M.D.

49 months ago

Welcome to our Forum and thanks for your questions. Thanks as well for your commitment to safe sex. When it is taken as prescribed, PrEP is close to 100% effective with nearly all of the few infections which occur occurring in persons who do not take the medication as recommended. In addition, your favored sex acts are low risk. There are no proven cases of HIV which are the result of receipt of oral sex and the risk for infection in persons performing oral sex on an untreated, HIV infected person is less than 1 infection for 10,000 sex acts. The presence of a mouth ulcer or sore does not meaningfully change that tiny risk.

I hope this information is helpful. If there are further questions or any part of my answer is unclear, please don’t hesitate to use your up to two follow up questions for clarification. EWH

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49 months ago

Thanks so much for taking the time to respond :)

I am aware that PrEP studies primarily involved anal sex (rectal absorption of the medications). What are your thoughts on PrEP providing protection for oral sex? Do you think it works in a similar manner?

Also, I had read that being on PrEP can delay a positive HIV result (if one were to become positive while on PrEP). Thoughts?

Thanks again

Edward W. Hook M.D.

49 months ago

I’m glad my initial responses were helpful. I will try to address your follow-up questions although I am unsure about your reference to rectal absorption of medications Perhaps you mean rectal inoculation of the virus.

It is difficult to provide site specific information on the protective affect of PrEP. In all study conditions infections are relatively uncommon and many persons engage in exposure at more than one site during their sexual encounters. In general the reason that it is believed that PrEP is more effective for rectal infection is because receptive rectal intercourse is the riskiest sort of exposure, leading to infection as often as once in every 200 exposures. Thus it is easier to prove the effect of PrEP. On the other hand, with respect to oral sex, there has never been a proven case of HIV acquired from receipt of oral sex. The risk of acquisition of HIV from performing oral sex on an infected untreated partner is very low (estimated to be less than one infection for every more than 10,000 exposures - in other words like performing oral sex on an infected partner daily for more than 27 years. As a result of how uncommon infections are following following oral exposures, it would be almost scientifically impossible to provide an estimate of how much lower use of PrEP would make the risk for acquisition of infection through performing oral sex on an untreated infected partner.

As I mentioned above, PrEP is very, very effective. In that small portion of people who do acquire infection however it is logical that the anti-HIV medication which are used as prep might delay development of a positive test..

EWH

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