Individuals who use opiates such as morphine, hydromorphone, or oxycodone may experience withdrawal symptoms within six to 12 hours of the last dose.
Many deaths have been linked to LSD use, including suicides and fatal accidents which occur as part of bad trips.
Use of amphetamines can cause an individual to become psychologically dependent on to them so that they are so central to a person's thoughts, emotions, and activities that the need to continue their use becomes a craving or compulsion.
Studies indicate that the effects of acute doses of Ecstasy affect the areas of the brain involved in higher thought processes, raising concerns regarding possible long-term effects on both infrequent and regular users of Ecstasy.