I recently saw a transgender sex worker. I rubbed my genitals against their anus. I didn’t feel the head of my penis go in. I asked the person as well and they said it didn’t. But my concern is that my tip maybe touched the wall of their anus and maybe that’s a risk? Should I take PEP? I don’t think I put it in, therefore no risk but I’m concerned.
That isn't a realistic risk and certainly doesn't merit PEP. A few seconds of touching, or even a few seconds of accidental penetration, is not likely to result in the transmission of anything at all, including HIV.
Right. But I’m not 100% sure. Maybe I’m paranoid. I asked the person if they felt me penetrate and they said no. I was just rubbing my penis against their anus. I would assume if any penetration occurred it would’ve been felt and clearly the other person would’ve as well. I’m not sure if by me rubbing my penis against their anus, even if the tip of the penis was very close to entering the anus, if there’s any risk.
Both of you said there was no penetration and you would each know, so I'm guessing there wasn't. Previous advice covered the rubbing aspect so there is no reason to sort of mix it in with the idea of penetrating to think that somehow a rubbing risk can occur from what was not a risk - that's overthinking the no-risk event.
In summary, move on and stop worrying.