Phentermine-Associated Atrial Fibrillation: A Case Report and Literature Review

Obesity has become a major public health problem with increased prevalence and is associated with cardiovascular mortality. Phentermine is approved for short-term obesity treatment in conjunction with lifestyle modifications. Palpitations are a well-documented side effect of phentermine, but atrial fibrillation (AF) is rarely reported. We present a case of new-onset AF in a healthy woman who had been recently started on phentermine for weight loss. LEARNING POINTS: Atrial fibrillation usually occurs secondary to intrinsic disorders such as hypertension, coronary artery disease, abnormal heart valves, thyroid dysfunction and medication side effects. Phentermine is used for a short period together with diet and exercise to treat obesity; atrial fibrillation is an unusual cardiovascular side effect of phentermine that warrants clinician caution. The importance of medication reconciliation is exemplified in this case as it is essential to rule out secondary causes of atrial fibrillation, including medication side effects.