Phentermine in the Modern Era of Obesity Pharmacotherapy: Does It Still Have a Role in Treatment?

Purpose of Review This review provides an overview of the history, mechanism of action, and expected treatment effects of the anti-obesity medication (AOM), phentermine. It also includes a summary of recent research and practical guidance for prescribing clinicians. Recent Findings Recent research on phentermine is sparse and consists primarily of observational studies with methodologic limitations. These studies suggest that phentermine use is associated with clinically significant weight loss in adults and that the medication is generally well tolerated. Large-scale observational studies evaluating phentermine’s safety have not identified an increased risk of cardiovascular events or elevations in blood pressure. There is no data to support the notion that phentermine is addictive. Summary Although it remains the most commonly prescribed AOM in the USA, phentermine has little rigorous research to support its efficacy and safety in long-term treatment, which creates a dilemma with guideline-recommended chronic use of AOMs. While we await forthcoming conclusive data on this front, clinicians may consider using phentermine long-term in selected patients, if such prescribing is consistent with local regulatory statutes.