Stimulants Unlike the narcotics and other depressants, stimulants increase activity in the central nervous system, speeding up metabolism and unleashing feelings of energy and confidence while curbing appetite and fatigue. In addition to curbing appetite and increasing fat metabolism, ephedra is a potent CNS stimulant. Rounding out the list is cocaine, which is still around, still expensive, and still causing serious problems. Like alcohol and downers, stimulants are all much more alike than they are different, both in their effects and the risks they pose.
Speed is speed.
One reason that users tend to crash so often is because speed causes a rapid buildup of tolerance, which means that the drugs' effects fade after a few weeks, unless dosage is increased. For some reason, this doesn't generally apply to stimulants prescribed for attention-deficit disorder, but it does apply to the ones prescribed for weight control. And it especially applies to crystal meth, which causes such powerful feelings of euphoria that users want to increase dosage. Heavy use can unleash profound psychological changes. In its most severe form, a toxic psychosis can emerge, characterized by hallucinations, paranoia, a feeling of bugs crawling on the skin, and bizarre behavior.