Vivus' proprietary oral capsule containing phentermine and extended-release (ER) topiramate has been approved in the US for the treatment of obesity. Phentermine is an appetite suppressant, while topiramate is an anti-epileptic medication. The once-daily formulation, known as Qsymia™, is designed to produce weight loss by decreasing appetite and increasing satiety. The product is also in clinical development for sleep apnoea syndrome and type 2 diabetes mellitus. This article summarizes the milestones in the development of phentermine/topiramate ER leading to this first approval for obesity.