I've never been on Pristiq (Desvenlafaxine), but have been on Effexor (Venlafaxine), Desvenlafaxine is a synthetic form of the isolated major active metabolite of venlafaxine, thus suggesting it has a much quicker onset, but basically the same drug, the shrooms or MDMA like feeling is normal for this med, as is common knowledge, Venlafaxine/Desvenlafaxine are structurally so similar to Phencyclidine (PCP/Angel Dust) the med can show a false positive
http://en.wikipedia.org/wiki/Venlafaxine , also if your not familiar with PCP/Angel Dust
http://en.wikipedia.org/wiki/Phencyclidine There is also the chance your MDMA was not actually MDMA but actually PCP as per here,
http://www.cesar.umd.edu/cesar/drugs/pcp.pdf , PCP is also mixed with dyes to produce colored powder, tablets or capsules
