Amphetamines are synthetic stimulants including speed, methylamphetamine (crystal meth, ice) and Methylphenidate (Ritalin), which is used to treat Attention Deficit Syndrome (ADD, ADHD) in children. As a street drug, amphetamines are normally supplied as a white, yellow or pink powder, crystals, tablets or as a putty-like substance known as base. Amphetamines can be snorted, ingested, smoked or injected.