I take SSRI's, should I stay away from Cocaine or MDMA?

Mixing these drugs can be risky, especially if there's a history of anxiety, as the comedown and next days are likely to involve more anxiety attacks. Also, the crash may be very unpleasant for someone already being treated for depression or similar conditions.

Also "Wellbutrin suppresses dopamine release in the brain, the main neurotransmitter at the root of the cocaine effect. It is actually given to cocaine addicts to help ease cocaine craving so it may in fact suppress cocaine's effects." (see http://www.thegooddrugsguide.com/cocaine/faq.htm)

MDMA with SSRIs typically means the MDMA won't work or work as well. For more information, see what our friends at Erowid had to say, here.