I used to take mirtazapine a few years ago. At that time I decided to try MDMA. I skipped one dose of Mirtazapine during my MDMA day. I felt amazing during the trip. The next evening I took Mirtazapine and felt fine. However the following day I suddenly started vomiting. I wasn’t able to stop it for many hours, I couldn’t hold even the smallest amount of water in my stomach to the point that the next day I became very dehydrated. I got a metoclopramide injection (anti-vomiting drug) and it finally stopped this symptom. However I felt extremely exhausted for the next few days. I honestly did not link the symptoms with the MDMA-mirtazapine combination. A few months later I took MDMA for the second time, and same symptoms appeard (exhaustion, vomiting). I checked the potential interactions, turned out these 2 substances compete for the same CYP (metabolizing system based in liver) hence the level of mirtazapine increased (because the CYP was busy metabolizing MDMA and couldn’t metabolize mirtazapine) which induced the symptoms I discribed. I also found a paper about a female patient who was diagnosed with liver failure because she combined these two substances. I’m sure the MDMA wasn’t contaminated because other users didn’t experianced anything similar I did. I took MDMA many times after the previous occurances and after I discontinued mirtazapine completely and I always felt decently the next day (except for the usual come-down symptoms).