Flushing one's brain with serotonin can completely destroy the body's ability to regulate internal temperature. Dancing all night, and in a jammed crowd, does not help. Heat strokes and seizures ensue, as do kidney and liver failures. This is why people die at raves. That is good, but they should not drink too much.
Brain swelling from reduced sodium levels in the blood can kill, as can a ruptured bladder.
Studies have already demonstrated that serotonin levels are significantly lower in people who have used ecstasy than in people who have not. Studies have also revealed memory failure for E users. This is all not to mention the former E users who are now in psychiatric treatment. There are more than enough cases in which E has triggered a horrifying psychological trauma. Many users have testified that they had numerous great trips on E and then suddenly, during one trip, they suffered some kind of frightening flashback, or a nightmarish hallucination, from which they suffered a nervous breakdown.