Adipex is a form of the drug Phentermine an amphetamine which part of a class of drugs known as anorectics. This drug is used to help in weight reduction for overweight individuals who are on a low-calorie diet and who are exercising and under the care of a physician. It suppresses the appetite. It should be taken for a limited period as it can be addictive. It should only be taken under the direction of the treating physician.