The effects of methamphetamine on humans are profound. SAMHSA is currently testing the effectiveness of various treatment regimens for methamphetamine, an addiction that is extremely difficult to treat. The stimulant effects from methamphetamine can last for hours, instead of minutes as with crack cocaine. Often the methamphetamine user remains awake for days. As the high begins to wear off, the methamphetamine user enters a stage called "tweaking," in which he or she is prone to violence, delusions, and paranoia. Many methamphetamine users try to alleviate the effect of the methamphetamine "crash" by buffering the effects with other drugs such as cocaine or heroin. Like heroin and cocaine, methamphetamine can be snorted,smoked, or injected.

Source: SAMHSA, OAS, TEDS (Jan 1998)

Overall usage. The 1997 NHSDA estimated that 5.3 million Americans (2.5 percent of the population) have tried methamphetamine in their lifetime, up significantly from the 1994 estimate of 1.8 million. The ADAM system reports that methamphetamine use continues to be more common in the western United States than in the rest of the nation. Methamphetamine use, according to ADAM, increased substantially in 1997, negating the progress achieved in 1996. In San Diego, roughly 40 percent of both male and female arrestees tested positive for methamphetamine.