What are GLP-1 drugs?

GLP-1 receptor agonists mimic glucagon-like peptide-1, a hormone the gut releases after a meal. They help the pancreas release insulin when blood sugar is high, slow how quickly the stomach empties, and act on appetite centres in the brain so people feel full sooner and eat less. First developed for type 2 diabetes, several are now approved for chronic weight management.

The main drugs and brands

  • Semaglutide — sold as Ozempic (type 2 diabetes), Wegovy (weight management) and Rybelsus (an oral tablet for diabetes).
  • Tirzepatide — sold as Mounjaro (diabetes) and Zepbound (weight management). It activates both the GLP-1 and GIP receptors, which is why it is called a “dual agonist.”
  • Liraglutide — an older, daily injection sold as Victoza and Saxenda.

The pipeline behind them is crowded: oral small-molecule pills, “triple agonists,” once-monthly injections and drugs designed to preserve muscle are all in development.

Benefits beyond the scale

In a large outcomes trial, semaglutide reduced heart attacks, strokes and cardiovascular deaths in people with heart disease and overweight or obesity. Researchers are also studying effects on kidney and liver disease, sleep apnoea, addiction and the brain — but many of those findings are early or observational, so treat headlines with care.

Side effects and cautions

The most common side effects are gastrointestinal — nausea, vomiting, diarrhoea and constipation — especially while the dose is being increased. Rarer risks include pancreatitis and gallbladder problems. The labels carry a warning about thyroid C-cell tumours seen in rodents, and these drugs are not used in people with a personal or family history of medullary thyroid cancer or MEN2. Weight commonly returns after stopping, and part of the weight lost can be muscle, which is why strength training and adequate protein are often recommended. Compounded or counterfeit versions sold outside normal pharmacy channels have drawn repeated FDA warnings.

How to use this guide

Below is every RxWyre article on GLP-1 and obesity medicines — approvals, trial results, safety news and the business of the obesity market — newest first. This page is general information, not medical advice; decisions about these medicines belong with a clinician.