Ecstasy. Selection of branded ecstasy (3,4- methylenedioxymetamphetamine) pills. Ecstasy is an illegal drug which induces feelings of elation, energy and well-being. Short-term side effects include dehydration, loss of control and appetite; long-term problems include memory and weight loss. Research suggests that ecstasy is a neurotoxin. Several ecstasy-related deaths have occurred, mainly due to dehydration.