One Molecule, Many Names
Semaglutide is an anti-diabetic medication used to treat type 2 diabetes, and an anti-obesity medication used for weight management. It can be given by subcutaneous injection or taken orally.
The naming is genuinely confusing, because the same molecule is sold under different brands for different uses. Its originator Novo Nordisk sells it worldwide as Ozempic and Rybelsus for diabetes, and as Wegovy for weight management. Under the brand names Wegovy and Kayshild it is also used to treat metabolic-associated steatohepatitis and liver cirrhosis, and Wegovy is additionally used to reduce the risk of heart attacks.
It is also sold as a generic drug by several companies in the Indian and Canadian markets. So the drug people argue about under one famous brand name is, chemically, the same substance appearing in several very different conversations at once.
Imitating a Gut Hormone
Semaglutide is a peptide similar to the hormone glucagon-like peptide-1 (GLP-1), modified with a side chain, and it acts as a GLP-1 receptor agonist.
An agonist is a substance that activates a receptor the way the body's own signalling molecule would. So rather than introducing a foreign mechanism, semaglutide impersonates a hormone the body already uses — one involved in regulating blood sugar and appetite.
That design explains both the intended effect and the side effects. The most common are nausea, vomiting, diarrhea, abdominal pain and constipation — a cluster concentrated in the digestive system, which is where the hormone it mimics does much of its work. The side chain modification is what allows it to persist in the body long enough to be practical as a medication.
Approved Quietly, Then Everywhere
Semaglutide's regulatory history looks unremarkable until you set it beside its later fame.
It was approved for medical use in the United States in 2017, then in Canada, the European Union and Japan in 2018, and in Australia in 2019.
Those approvals passed without much public attention. What followed did not. In 2023, semaglutide was the nineteenth most commonly prescribed medication in the United States, with more than 25 million prescriptions. A drug approved for diabetes six years earlier had become one of the most prescribed medicines in the country — a scale of adoption that pharmaceutical products almost never reach that quickly, and one driven largely by a use that was not its original headline indication.
On the Essential Medicines List
Semaglutide appears on the World Health Organization's List of Essential Medicines — the set of medicines the WHO considers necessary for a basic functioning health system.
That listing is a meaningful marker. It is not a popularity ranking; it signals that a medicine is judged to meet priority health needs, taking efficacy, safety and comparative cost into account.
Its range of approved uses keeps widening in a way that is unusual for a single molecule: type 2 diabetes, weight management, metabolic-associated steatohepatitis, liver cirrhosis, and reducing heart attack risk. Each of those is a distinct patient population with a distinct clinical problem. The reason one drug reaches so many is that it works on a hormonal signalling pathway which sits upstream of several conditions at once — which is also why its story has become as much about supply, demand and access as about pharmacology.
