Short-term effects of methamphetamine on the body include increased physical activity, increased wakefulness, decreased appetite, elevated body temperature and irregular heartbeat, according to the National Institute on Drug Abuse. Long-term effects include anxiety, confusion, violent behavior, mood disturbances and psychotic behaviors.
Methamphetamine acts as a powerful stimulant even in small doses, and short-term effects include increased concentration and cardiovascular problems, according to the National Institute on Drug Abuse. Patients may also feel a rush of euphoria, possibly due to elevated levels of the neurotransmitter dopamine. Overdose can lead to convulsions and death if not treated immediately.
Long-term methamphetamine use can result in addiction and tolerance, the need to increase the dose or frequency of taking the drug to gain the desired effect, states the National Institute on Drug Abuse. Chronic users may stop feeling any pleasure when not using the substance. These users may exhibit a variety of psychotic features including paranoia, hallucinations and delusions, such as the feeling that insects are crawling under the skin. Even after the user quits methamphetamine usage, these psychotic symptoms can continue for months or years, often brought about by stress. Long-term usage can also cause changes in brain structure and function, resulting in cognitive problems such as impaired verbal learning, decreased motor function and memory loss.