Phentermine is indicated only for short-term treatment, and tolerance often develops. Common adverse effects associated with phentermine are dry mouth, insomnia, increased blood pressure, and constipation.
– Am J Health Syst Pharm 2001 Jul 15;58(14):1301-8 – Pharmacologic options for the treatment of obesity. – Campbell ML, Mathys ML.



When phentermine was mixed with other unlabeled reversible MAO inhibitors (e.g. pseudoephedrine, ephedrine, norephedrine; estradiol benzoate), the degree of MAO inhibition was additive. The cardiac valvular lesions and primary pulmonary hypertension that have been reported to be associated with fenfluramine-phentermine use may have resulted from the intermittent concurrent blockage of both serotonin uptake and metabolism.
– Biochem Pharmacol 2000 Jun 15;59(12):1611-21 — Characterization of phentermine and related compounds as monoamine oxidase (MAO) inhibitors. — Ulus IH, Maher TJ, Wurtman RJ.



Fenfluramine, dexfenfluramine, and phentermine have been used alone or in combination as an alternative to diet and surgery in the management of obesity. This therapy was halted in 1997 after reports of valvular lesions affecting almost one third of patients treated with these drugs.
– Curr Opin Cardiol 2002 Sep;17(5):486-92 — Appetite suppressants and valvular heart disease. — Seghatol FF, Rigolin VH.



The risk of valvular heart disease is significantly increased by fenfluramine, dexfenfluramine, and phentermine.
– BMC Clin Pharmacol 2002 Aug 23;2(1):6 — Appetite suppressants and valvular heart disease – a systematic review. — Loke YK, Derry S, Pritchard-Copley A.



Combined cardiac valvular disease and pulmonary hypertension appear to occur frequently in patients receiving fen-phen, and more autopsy cases of patients with a history of fen-phen usage are warranted to document the frequency of combined cardiac valvular disease and pulmonary hypertension in the United States.
– Chest 2002 Feb;121(2):649-52 — Autopsy findings of heart and lungs in a patient with primary pulmonary hypertension associated with use of fenfluramine and phentermine. — Tomita T, Zhao Q.



Phentermine significantly prolonged the vasoconstrictive effect of serotonin due to inhibition of its metabolic breakdown.
– Clin Exp Pharmacol Physiol 1976 Jul-Aug;3(4):323-30 — On the role of serotonin in the pathogenesis of pulmonary hypertension induced by anorectic drugs; an experimental study in the isolated perfused rat lung, II. Fenfluramine, mazindol, mefenorex, phentermine and R 800. — Seiler KU, Wassermann O, Wensky H.



This case represents the first report of acute interstitial nephritis associated with phentermine or phendimetrazine.
– Clin Nephrol 1998 Oct;50(4):252-4 — Acute interstitial nephritis following treatment with anorectic agents phentermine and phendimetrazine. — Markowitz GS, Tartini A, D’Agati VD.



Phentermine is a central nervous system stimulant that can increase brain dopamine levels and has a structure similar to amphetamine. Reports of a case of schizophreniform-like psychotic disorder induced by phentermine in a young woman without a personal or family history of psychiatric disorders.
– Zhonghua Yi Xue Za Zhi (Taipei) 1998 Jan;61(1):44-7 — Schizophreniform-like psychotic disorder induced by phentermine: a case report. — Lee SH, Liu CY, Yang YY.



Sympathomimetic amines used as appetite suppressants can produce heat intolerance by two mechanisms: they increase endogenous heat production as a result of their stimulatory effects on the central nervous system, and they impede the dissipation of heat from the body by producing peripheral vasoconstriction.
– S Afr Med J 1982 Dec 4;62(24):905-6 — Fatal heat-stroke in a child taking appetite-suppressant drugs. — Kew MC, Hopp M, Rothberg A.



Consult with your physician before using herbs or herbal products especially if they are advertised as having an effect on the heart. Not recommended if you are pregnant, planning to be or breastfeeding. Not recommended for children. Avoid alcohol while taking phentermine.