Methamphetamine (also called meth, crystal, chalk, and ice, among other terms) is an extremely addictive stimulant drug that is chemically similar to amphetamine. It takes the form of a white, odorless, bitter-tasting crystalline powder.
Methamphetamine is taken orally, smoked, snorted, or dissolved in water or alcohol and injected. Smoking or injecting the drug delivers it very quickly to the brain, where it produces an immediate, intense euphoria. Because the pleasure also fades quickly, users often take repeated doses, in a “binge and crash” pattern.
People who use methamphetamine long-term may experience anxiety, confusion, insomnia, and mood disturbances and display violent behavior. They may also show symptoms of psychosis, such as paranoia, visual and auditory hallucinations, and delusions (for example, the sensation of insects crawling under the skin).
Chronic methamphetamine use is accompanied by chemical and molecular changes in the brain. Imaging studies have shown changes in the activity of the dopamine system that are associated with reduced motor skills and impaired verbal learning. In studies of chronic methamphetamine users, severe structural and functional changes have been found in areas of the brain associated with emotion and memory, which may account for many of the emotional and cognitive problems observed in these individuals.
Taking even small amounts of methamphetamine can result in many of the same physical effects as those of other stimulants, such as cocaine or amphetamines. These include increased wakefulness, increased physical activity, decreased appetite, increased respiration, rapid heart rate, irregular heartbeat, increased blood pressure, and increased body temperature.
Long-term methamphetamine use has many negative consequences for physical health, including extreme weight loss, severe dental problems (“meth mouth”), and skin sores caused by scratching.
Methamphetamine use also raises the risk of contracting infectious diseases like HIV and hepatitis B and C. These can be contracted both by sharing contaminated drug injection equipment and through unsafe sex. Regardless of how it is taken, methamphetamine alters judgment and inhibition and can lead people to engage in these and other types of risky behavior.