Methamphetamine is a highly addictive stimulant that affects the central nervous system. It comes as a white powder or clear crystal chunks that are smoked or injected. The drug has a long history but became popular in the US in the 1950s. It is produced illegally by extracting ingredients from cold medicines and combining them with toxic chemicals. Short term effects include increased activity and heart rate, while long term use can cause physical and mental health issues. Meth is addictive and illegal, with prison sentences and fines for possession.