Adipex (Phentermine) is a prescription medication used for weight loss. It's an appetite suppressant that affects the central nervous system to help reduce hunger and assist in weight reduction for obese patients. Typically, it's used short-term alongside a doctor-approved exercise, behavior change, and reduced-calorie diet program. Common side effects include increased heart rate, dry mouth, and insomnia. Adipex is not suitable for people with certain medical conditions like heart disease, uncontrolled high blood pressure, or a history of drug abuse.