Methamphetamine ( listen) (also known as methamfetamine (INN
International Nonproprietary Name
An International Nonproprietary Name is the official nonproprietary or generic name given to a pharmaceutical substance, as designated by the World Health Organization...

), N-methylamphetamine, methylamphetamine, and desoxyephedrine) is a psychostimulant of the phenethylamine
Phenylethylamine or phenethylamine is a natural monoamine alkaloid, trace amine, and also the name of a class of chemicals with many members well known for psychoactive drug and stimulant effects. Studies suggest that phenylethylamine functions as a neuromodulator or neurotransmitter in the...

 and amphetamine
Substituted amphetamine
Substituted amphetamines are a chemical class of stimulants, entactogens, hallucinogens, and other drugs. They feature a phenethylamine core with a methyl group attached to the alpha carbon resulting in amphetamine, along with additional substitutions...

Chemical classification
Chemical classification systems attempt to classify as elements or compounds according to certain chemical functional or structural properties. Whereas the structural properties are largely intrinsic, functional properties and the derived classifications depend to a certain degree on the type of...

 of psychoactive drugs. When used illicitly, methamphetamine is commonly referred to as "crystal meth", "meth", "crystal", "ice", "p", "shabu", "speed", "shit", or "glass".

Methamphetamine increases alertness, concentration, energy, and in high doses, may induce euphoria, enhance self-esteem and increase libido
Libido refers to a person's sex drive or desire for sexual activity. The desire for sex is an aspect of a person's sexuality, but varies enormously from one person to another, and it also varies depending on circumstances at a particular time. A person who has extremely frequent or a suddenly...