Amphetamine was first synthesized in 1887 in Germany. Initially called phenylisopropylamine, it was, for a long time, a drug in search of use, trying to find application from decongestion to depression. In the 1930s , it was initially marketed as Benzedrine, as an over-the-counter inhaler to treat nasal congestion and asthma.
Methamphetamine was discovered in Japan in 1919. The crystalline powder was soluble in water, making it a perfect candidate for injection. In the late 30s, it found use for narcolepsy and ADHD (attention deficit hyperactivity disorder). It is still legally produced in the U.S., sold under the trade name Desoxyn (Abbott. PDR 2001) with indications for ADHD and for short-term therapy in exogenous obesity.
During World War II, amphetamines were widely used as stimulants to keep the fighting men going (during the Viet Nam war, American soldiers used more amphetamines than the rest of the world did during WWII). And after World War II, when military surplus became available to the public, methamphetamine abuse became epidemic.