Considering the meds you are on, it is not safe at all to trip on dxm. Serotonin syndrome is a possibility which can be very dangerous (life threatening). Please do not take DXM or MDMA.
I believe you can trip on stuff like LSD or mushrooms safely however for some people being on SSRI like sertraline may dull the effects of LSD considerably. For example, some people report they trip fine while on antidepressants, some report they get weaker effects, some report they don't feel anything at all.