Phentermine

Phentermine, sold under the brand name Adipex-P among others, is a medication used together with diet and exercise to treat obesity. It is available by itself or as the combination phentermine/topiramate. Phentermine is taken by mouth. Common side effects include a fast heart beat, high blood pressure, trouble sleeping, dizziness, and restlessness. Serious side effects may include abuse, but do not include pulmonary hypertension or valvular heart disease, as the latter complications were caused by the fenfluramine component of the "fen-phen" combination. Phentermine is a norepinephrine and dopamine releasing agent (NDRA) and produces stimulant, rewarding, and appetite suppressant effects. Chemically, it is a substituted amphetamine. Phentermine was approved for medical use in the United States in 1959. It is available as a generic medication. In 2023, it was the 168th most commonly prescribed medication in the United States, with more than 3 million prescriptions. Phentermine was withdrawn from the market in the United Kingdom in 2000, while the combination medication fen-phen, of which it was a part, was withdrawn from the market in 1997, due to side effects of fenfluramine.