
The most widely known (undesired) effect of the drug is overexertion and sweating, leading to the ecstasy user drinking large amounts of water and being in danger of hyponatremia (the depletion of solutes from the blood plasma), which can eventually lead to cerebral edema. The drug has also been known for causing “holes in the brain”, Parkinsonian tremors, and permanent brain damage from single use, however these claims have been discredited* and retracted from the literature (1). Some research has shown that the drug may not be as toxic as once thought when used in moderation, but that does not address whether environmental effects could change the action of the drug and potentially make it more dangerous than a “traditional” toxicity study might suggest.

The data showed that a low dose of MDMA combined with sound caused decreased ECoG spectrum power significantly different from control, but no significant effect when MDMA was administered without sound. A high dose of MDMA combined with sound produced a dramatic effect that lasted for 5 days, while all other treatments had no long term effects. This powerful data shows a synergistic relationship between exposure to loud noise and the effect of MDMA on higher neural function, and suggests that higher doses only have long term effects when combined with loud noise. The authors do not suggest a possible mechanism for this effect, but they do warn that the drug may be more dangerous than commonly thought since most ecstasy users combine the drug with loud music.
* As a side note, some legislation around ecstasy was driven by the above mentioned discredited “findings”, which is disconcerting. An example is the RAVE act (3), introduced in 2002 by current Democratic VP candidate Joe Biden as part of the War On Drugs, which allows the law to shut down clubs and raves if ecstasy use is suspected to occur on their premises. The drug is still a dangerous one, but one would hope that laws would be revised after research they were based upon is discredited, which they were not.
References
1. Ronald Bailey: “The Agony of Ecstasy Research”. ReasonOnline.
2. Michelangelo Iannone, Stefania Bulotta, Donatella Paolino, Maria Zito, Santo Gratteri, FrancescoS Costanzo, Domenicantonio Rotiroti (2006). Electrocortical effects of MDMA are potentiated by acoustic stimulation in rats BMC Neuroscience, 7 (1) DOI: 10.1186/1471-2202-7-13
3. http://en.wikipedia.org/wiki/RAVE_Act