Ozempic v Mounjaro: what is the difference between semaglutide and tirzepatide?

Glucagon-like peptide-1 (GLP-1) agonists are a second line treatment for people with type 2 diabetes, used when diet, exercise, and oral tablets such as metformin are not fully effective for controlling blood glucose levels. GLP-1 agonists target the incretin system, which controls glucose stimulated insulin secretion.1

The compounds themselves are nothing new; the first GLP-1 agonist, exenatide, was licensed in the US in 2005 and in the European Union in 2006. What has changed in recent years is their newfound effectiveness for weight loss,2 and possibly many other conditions.3

“Obesity can be considered a global pandemic; the rate of increase in body mass index (BMI) across the world and among various populations has been exponential,” says Jagdish Khubchandani, professor of public health at New Mexico State University in the US. “These treatments can help reduce the rate of increase in obesity, but they need to be broadly available, ensure safety, and be combined with other strategies that focus on diet and exercise.”

There are two leading GLP-1 agonists on the market. Semaglutide—manufactured and marketed by Novo Nordisk as Ozempic for type 2 diabetes and Wegovy for weight loss—was the first, becoming available on the NHS in the UK in September 2023. This was followed by tirzepatide—made by Eli Lilly and marketed as Mounjaro for type 2 diabetes and weight loss in the UK, and as Zepbound for weight loss in the US—which was approved by the Medicines and Healthcare Products Regulatory Agency (MHRA) in January 2024 and recommended by the National Institute for Health and Care Excellence (NICE) in October for some patients with obesity and related conditions.4

How do they compare …