Semaglutide

Semaglutide is a TGA-registered, prescription-only GLP-1 receptor agonist used for type 2 diabetes (Ozempic) and chronic weight management (Wegovy). Large STEP trials showed average weight loss of roughly 15% over 68 weeks.

What it is

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist — a medicine that mimics a natural gut hormone released after eating. In Australia it is sold under two brand names: Ozempic, registered for type 2 diabetes, and Wegovy, registered for chronic weight management. An oral semaglutide tablet for weight management received approval in Australia in late 2025. Semaglutide is a Schedule 4 (prescription-only) medicine.

How it works

Semaglutide activates GLP-1 receptors in the pancreas, gut and brain. In broad terms it prompts the pancreas to release insulin when blood glucose is high, slows how quickly the stomach empties, and acts on appetite centres in the brain to increase fullness and reduce hunger. It is taken as a once-weekly injection (or daily tablet for the oral form), with the dose increased gradually to reduce side effects.

What the evidence says

Semaglutide for weight management was studied in the STEP trial programme. In STEP-1, adults with obesity without type 2 diabetes who received semaglutide 2.4 mg lost an average of about 14.9% of body weight over 68 weeks alongside lifestyle measures. Across STEP, mean reductions of roughly 10–18% were reported. In the head-to-head SURMOUNT-5 trial against tirzepatide, semaglutide produced an average reduction of about 15% at 72 weeks. These are strong, replicated human results. Trials also show weight tends to be regained when the medicine is stopped, and results were measured alongside diet and activity support.

Legal & regulatory status in Australia

Semaglutide is a TGA-registered prescription medicine (Schedule 4). Ozempic is approved for type 2 diabetes and Wegovy for chronic weight management in eligible adults. Supply has been affected by well-documented shortages. The TGA has raised specific concerns about compounded "semaglutide" products — these are not TGA-evaluated and are not held to the same safety, quality or efficacy standards as registered medicines — and has issued alerts about counterfeit products.

Risks & considerations

The most common side effects are gastrointestinal — nausea, vomiting, diarrhoea and constipation — usually worse early and during dose increases. Less common but more serious concerns include pancreatitis, gallbladder problems, and low blood glucose when combined with certain diabetes medicines. Animal studies raised a thyroid-tumour signal, so it is contraindicated with a personal or family history of medullary thyroid carcinoma or MEN2. It is not recommended in pregnancy.

What to ask a doctor

• Is this medicine appropriate for my health profile and goals, and which indication applies to me?
• What are the likely side effects for me, and how would we manage them?
• What monitoring and follow-up will I need?
• What happens to my weight or glucose control if I stop?
• Given shortages, what are the supply and continuity considerations?

FAQ

Q: Is semaglutide approved in Australia? A: Yes. It is TGA-registered and prescription-only (S4), sold as Ozempic (type 2 diabetes) and Wegovy (weight management). Q: How much weight did people lose in the trials? A: In STEP-1, adults without diabetes lost an average of about 14.9% of body weight over 68 weeks alongside lifestyle support; results vary between individuals. Q: Are compounded versions the same thing? A: No. The TGA has flagged compounded semaglutide as a concern — it is not TGA-evaluated and not held to the same standards as registered products.