Can PrEP prevent HIV infection?

Hi doctor,

I had sexual exposure with a girl five days ago. Her HIV (Human Immunodeficiency Virus) status is unknown, but she had no symptoms or bumps, and she told me she had more than 20 sexual partners (some of whom she had unprotected intercourse with). I engaged in insertive vaginal sex (with a condom) and received oral sex (without a condom). I did not notice any break in the condom, although there were periods of friction. Every time the friction increased, I changed to the new condom. As a precaution, before that night, I was also on on-demand PrEP (Pre-exposure Prophylaxis). The day of the encounter was my fifth day of daily PrEP, and I had taken a double dose the day before. In total, I had consumed six PrEP pills before exposure. After exposure, I continued to consume PrEP for three more days (two pills the next day, one pill the day after that, and one pill the day after). I stopped the on-demand regime yesterday. Hours after our meeting, I developed leg fatigue and became very anxious. The fatigue persisted only for one day (only in my legs). Today I also noticed three red dot rashes on my anterior chest (flat and not itchy). I am worried if this is an acute retroviral syndrome rash. So far, no fever or pharyngitis. I plan to take a PCR (Polymerase Chain Reaction) RNA (Ribonucleic Acid) test on day ten (in five days). How likely is it that I have contracted HIV, and is it likely for ARS rash to be present without fever in just five days?

Thank you.

Hi doctor,

Thank you for your reply. I have four follow-up questions. Please look at the following dosing schedule for PrEP (exposure stated) and let me know if you feel it would have been effective based on your knowledge. Some sources say seven days of Prep are required for full protection on the daily regimen, but I just did an on-demand dosing (with a little extra- about five days). On-demand dosing is recommended for anal sex. It is likely okay for heterosexual men to engage in vaginal sex (just that it is not studied in gay men only). They said seven days of daily dosing is recommended for women having vaginal sex because it takes seven days for PrEP to build up in vaginal tissue. Would the regime have been okay and worked for me? I stopped PrEP because it was already more than 48 hours after exposure (which is the recommendation to stop PrEP on demand). Is this okay, or should I continue? I will not have any further risky exposure in the coming weeks. So, is it okay that I stopped the medicine, or should I continue? For the rash, have you or a dermatologist on the site reviewed the picture with the arrows I sent before explaining? I was worried because of the flat papular nature of the rash. If you have reviewed the picture and feel that this rash (after five days) is unlikely to be due to HIV, then that is fine. I have reattached the photo to this query. Since the exposure from day one, I have been feeling fatigued in my legs. Could this be caused by anxiety or a PrEP side effect? What else could cause it?

Thank you.