Phentermine is a sympathomimetic amine with pharmacological activity similar to amphetamines, primarily used as an appetite suppressant in the management of obesity. It functions by stimulating the central nervous system, increasing heart rate and blood pressure, and decreasing appetite, which can aid in weight loss when combined with diet and exercise.

As a short-term adjunct in a regimen of weight reduction, phentermine is typically prescribed for individuals with a body mass index (BMI) of 30 kg/m² or greater, or 27 kg/m² with associated risk factors such as hypertension, diabetes, or hyperlipidemia. The efficacy of phentermine in promoting weight loss has been demonstrated in various clinical studies, making it a valuable option for patients struggling with obesity-related health issues.

Phentermine is metabolized in the liver and excreted primarily by the kidneys, with a half-life ranging from 19 to 24 hours, allowing for once-daily dosing. It is important for prescribers to consider potential contraindications, such as cardiovascular disease, hyperthyroidism, or a history of drug abuse, when prescribing phentermine.

Common side effects may include increased heart rate, dry mouth, insomnia, and nervousness, which should be monitored throughout the treatment duration. Due to its potential for abuse and dependence, phentermine is classified as a Schedule IV controlled substance, necessitating careful patient selection and monitoring by healthcare providers.