Drugs that work in the brain are considered appetite suppressants. Amphetamines are approved for use in treating other diseases; their use as a weight loss drug is considered "off label" or not approved. Doctors often prescribe drugs for “off-label”…

The use of phentermine and fenfluramine, commonly known as phen-fen, for weight loss increased dramatically in the mid-1990s. Phen-fen usage brought about an impressive increase in the number of medication-dispensing weight loss clinics.