Amphetamines can be taken orally in pill or capsule form, intravenously injected, snorted or smoked. Amphetamines and meth-amphetamines have a similar but somewhat different molecular structure. Tolerance will develop to all drugs in this class. The slight differences in the pharmacological reactions and side effects of the different varieties of the amphetamines and their derivatives dictate their principal medical use. Some are used for appetite suppression, respiratory stimulation, etc.
Amphetamines can cause both acute and chronic toxicity.
Amphetamines are excreted slowly and cumulative effects may occur with continued administration. These effects may include high blood pressure and hallucinations. In regard to recreational use, the stimulation of the central nervous system usually causes an increase in motor activity and mental alertness, a mood elevation effect, a general sense of well-being and a decrease in appetite. Long term use can result in psychological dependency as well as a high degree of tolerance. Withdrawal often includes feelings of depression.