Key takeaways
Phendimetrazine and phentermine (Adipex-P) are both sympathomimetic medications used for short-term weight management in adults with a body mass index (BMI) of 30 kg/m² or greater, or 27 kg/m² with other risk factors like high blood pressure. Both medications are controlled substances and appetite suppressants meant to be used alongside diet and exercise. However, they differ in several ways. Phendimetrazine is available as immediate-release tablets and extended-release capsules and is taken 1 to 3 times daily, depeneding on the formulation. In contrast, phentermine is available in tablets, capsules, and orally disintegrating tablets and is typically taken once daily. Possible side effects of both medications include high blood pressure and heart rate, restlessness, and trouble sleeping. Both medications should not be combined with other weight loss medications or taken with MAOIs like selegiline (Zelapar).
