In a situation like this, one has to weigh the risks versus the benefits. Unprotected anal sex with another male who
is infected
is a significant risk, certainly significant enough to warrant PEP. Also, PEP is pretty effective in preventing transmission when started within 72 hours of the exposure (the sooner, the better), so for that reason alone, it's kind of a no brainer in your case.
To be frank, if I had a significant risk, I would not be worried about side effects.