How long does it take for PrEP to be effective?

[idontknow69]

Hello,
I received the prescription for PrEP and started it 3 days ago,I am a straight guy,after how long do I reach full protection by taking it every day at the same time for insertive vaginal sex?
My doctor told me that after two days I can have sex already,is that correct?

[Jim Allen]

Hiya, 

There isn't enough data with (daily) PrEP to say when the drug levels reach their max levels to protect the insertive partner.

However, we know that PrEP levels build up in the colorectal tissue (anus) first, followed by tissues in the rest of the body. For receptive anal sex, daily PrEP pills reach maximum protection at about seven days of daily use and 21 days for receptive vaginal sex.

So to answer your question, the estimate would be somewhere between seven and closer to 21 days.

[Jim Allen]

Remember to consider condoms for any intercourse and test more regularly as a PrEP user for STIs & HIV.

[idontknow69]

Thank you Jim for the answer.
Correct me if I am wrong,so PrEp on the demand which is considered to be effective for every kind of sex is considered safe just after taking 2 pills against the between 7 and the 21 pills of the daily one?

It’s not a bit contradictory?

[Jim Allen]

Correct me if I am wrong,so PrEp on the demand which is considered to be effective for every kind of sex is considered safe just after taking 2 pills against the between 7 and the 21 pills of the daily one?

It’s not a bit contradictory?

No, and PrEP 2-1-1 (On-demand) is only considered effective for:

People who bottom during anal sex;
People who top during anal sex; and,
People who top during front hole or vaginal sex.

If you want to switch to PrEP 2-1-1 (On-demand) as an additional layer of HIV prevention, then by all means, do after talking to your healthcare provider.

The critical key to PrEP 2-1-1 really is the initial double dose, and if you had started or start PrEP with a double dose and had continued with a single daily dosage afterwards, my answer would be slightly different. Now, we know daily PrEP takes time to reach the max levels in tissue; however, it could raise questions about the duration of the PEP protocol duration but without more studies and they will never happen it remains what it is.

https://www.cdc.gov/hiv/basics/prep/on-demand-prep.html
https://www.cdc.gov/hiv/basics/prep/prep-effectiveness.html

[idontknow69]

Thanks Jim for the clarification,
 I started daily prep from 4 days, taking one pill a day, so if tomorrow the fifth day I would take a double dose and then continue normally I would shorten the time to reach full protection right?

[Jim Allen]

In theory, yes.

https://i-base.info/guides/prep/real-life-examples-for-on-demand-dosing

[idontknow69]

 I have only one question left: I’m not taking original truvada but a generic,this story of the range of bioequivalence and bioavailability 80-125% can act on the effectiveness ?

[Jim Allen]

True generic has the same active ingredients, and there is no difference from the original. If you can the meds correctly and as prescribed, the drug levels should be just fine and effective.