It is used medically as an appetite suppressant for short term use, as an adjunct to exercise and reducing calorie intake. It should not be used by people who have a history of drug abuse, have cardiovascular disease, hyperthyroidism, glaucoma, or are pregnant, planning to become pregnant, or breast-feeding. It should not be taken by anyone taking a monoamine phentermine prescribing information pdf inhibitor.
Drinking alcohol while using phentermine may cause adverse effects. It was first introduced in 1959, and became part of the drug combination fen-phen that was withdrawn from the market in 1997 due to the fenfluramine component damaging people’s heart valves. Different formulations of phentermine as a single agent are available under various brand names, in many countries.
Phentermine is used for a short period of time to promote weight loss, if exercise and calorie reduction are not sufficient, and in addition to exercise and calorie reduction. Phentermine is approved for up to 12 weeks of use and most weight loss occurs in the first weeks. However, significant loss continues through the sixth month and has been shown to continue at a slower rate through the ninth month.
Phentermine may decrease the effect of drugs like clonidine, methyldopa, and guanethidine. Drugs to treat hypothyroidism may increase the effect of phentermine.
Rare cases of pulmonary hypertension and cardiac valvular disease have been reported. Tolerance usually occurs however risks of dependence and addiction are considered negligible. People taking phentermine may be impaired when driving or operating machinery. Consumption of alcohol with phentermine may produce adverse effects.