Semaglutide: Mechanism, Approval & SA Status

Semaglutide is a synthetic analogue of human GLP-1 (glucagon-like peptide-1), a hormone the gut releases after eating. It's approved, under prescription, as both a diabetes medicine and a weight-management medicine — and it's also one of the compounds most commonly sold, unregulated, as a "research peptide" in South Africa. Those are two very different regulatory situations for the same molecule.

How it works

Semaglutide binds and activates the GLP-1 receptor. That does three main things: it prompts the pancreas to release insulin only when blood glucose is elevated (glucose-dependent, so it doesn't drive hypoglycemia the way some older diabetes drugs can), it slows gastric emptying so food leaves the stomach more slowly, and it acts on appetite-regulating centres in the hypothalamus and brainstem to increase satiety. The net effect is lower post-meal blood sugar and reduced food intake — which is why the same molecule works for both type 2 diabetes and obesity.

Approval history

2017: first approved (as Ozempic) for type 2 diabetes.
2021: approved (as Wegovy) for chronic weight management in adults with obesity or overweight plus a weight-related condition.
March 2024: Wegovy's approval extended to reduce the risk of major cardiovascular events — heart attack, stroke, cardiovascular death — in adults with established cardiovascular disease and obesity or overweight.
More recently: an oral Wegovy tablet was approved for weight management, and the label has been extended to a liver condition (MASH) in some markets, per the manufacturer's own regulatory filings.

Source: FDA-approved prescribing information for Wegovy (semaglutide) injection, accessdata.fda.gov.

What the clinical trials showed

In the trials that supported the weight-management approval, participants on semaglutide lost significantly more body weight than those on placebo alongside diet and exercise — on the order of 15% of body weight on average over roughly a year and a half, in the pivotal STEP program. Later trials (including the oral formulation's OASIS program) reported similar double-digit percentage weight loss. These are trial averages under medical supervision, not a guarantee for any individual, and not something to extrapolate to an unsupervised, unregulated product.

Safety considerations the label calls out

Semaglutide's US label carries a boxed warning about thyroid C-cell tumors observed in rodent studies; it's contraindicated for anyone with a personal or family history of medullary thyroid carcinoma or Multiple Endocrine Neoplasia syndrome type 2. Common side effects in trials were gastrointestinal (nausea, vomiting, diarrhea). This is exactly the kind of risk profile a prescriber is meant to screen for before someone starts the medicine — which an unsupervised online purchase skips entirely.

South Africa status: South Africa's medicines regulator, SAHPRA, requires any product intended to treat or alter a bodily function to be registered before sale, and has specifically warned about unregistered peptide products sold online, through social media, gyms and informal suppliers. A registered medicine dispensed by a licensed pharmacist against a prescription is a different product, legally and practically, from a vial of "research-grade semaglutide" bought online with no prescription, no pharmacist, and no regulatory oversight of what's actually in it.

See our vendor comparison for how we evaluate documentation from vendors selling compounds like this as research chemicals, and how we rate for the full regulatory context.

This page is educational information about a molecule and its regulatory history. It is not medical advice, not a recommendation to use semaglutide outside a prescription, and not an endorsement of any vendor.