Adipex is a brand name for the medication phentermine hydrochloride. It's primarily used as a short-term adjunct to a reduced-calorie diet and exercise for weight loss in individuals with a BMI (Body Mass Index) of 30 kg/m² or higher, or in those with a BMI of 27 kg/m² or higher with risk factors such as high blood pressure, diabetes, or high cholesterol.

Phentermine works as a sympathomimetic amine, which means it stimulates the release of neurotransmitters like norepinephrine and dopamine, resulting in appetite suppression and increased energy expenditure. It's typically prescribed for short periods due to its potential for tolerance and addiction.