Hmm, I've tripped on most common psychocatives whilst being on prozac- DMT, salvia, mushrooms (psilocybe), lots of LSD, 2c-i and found the effects weren't particualrly dimisnhed, just had a different nature. Panicky sensations were decreased, though I didn't think euphoria was. I always consume a lot of drug when I do, so I didn't notice that my trips were any less intense or hallucinogenic then pre-Prozac trips.
Honestly, you should have researched this- one of the first things I did when I was first prescribed SSRI's was look at interactions with illegal drugs. This was for safety, desire to not worsen my condition (extreme anxiety) and because I didn't want to pump my head full of something that would have no effect. That way, I knew to expect a slightly different response from LSD and no effects from e, so I haven't touched that crap in years.
Oh yeah, combing DXM with SSRI's is potentially deadly. Research seratonin syndrome. Bad stuff