Semaglutide

Key facts

• Semaglutide (sold as Ozempic and Wegovy by injection, and Rybelsus as a tablet) is a GLP-1 receptor agonist. It mimics a gut hormone that boosts insulin release after meals and slows digestion.
• The injectable pens are used once a week under the skin; the tablet is taken once a day on an empty stomach. Effects on appetite and blood sugar build over several weeks as your dose is increased.
• Semaglutide carries a boxed warning: it caused thyroid C-cell tumours in animal studies. Do not use it if you or a close family member has had medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN2).
• Seek urgent care for severe abdominal pain that spreads to the back, which can signal pancreatitis, or for a new lump or swelling in the neck.

What semaglutide treats

Semaglutide improves blood sugar control in type 2 diabetes alongside diet and exercise. Higher-dose formulations are used for chronic weight management in adults who meet specific weight or health criteria. In adults with type 2 diabetes and established heart disease, it's also used to lower the risk of heart attack and stroke.

How semaglutide works

Semaglutide copies the action of GLP-1, a hormone your gut releases after eating. It tells the pancreas to release more insulin only when blood sugar is high, reduces the liver's glucose output, slows how fast the stomach empties, and acts on appetite centres in the brain to reduce hunger.

Before you take it

• Do not start semaglutide if you or a close relative has had medullary thyroid carcinoma or MEN2.
• Tell your prescriber about any history of pancreatitis, gallbladder disease, or diabetic eye disease (retinopathy), since rapid blood sugar improvement can temporarily worsen it.
• Avoid semaglutide in pregnancy; stop it well in advance if you're planning to conceive, as advised by your prescriber.
• Combining it with insulin or a sulfonylurea raises the risk of low blood sugar; those doses may need lowering.

Side effects

Common effects are nausea, vomiting, diarrhea, constipation, stomach pain, and reduced appetite, most noticeable after each dose increase and easing over time.

Stop and seek urgent medical care for any of these:

• Severe, persistent abdominal pain that spreads to the back.
• A lump, swelling, or hoarseness in the neck, or new difficulty swallowing.
• Signs of a serious allergic reaction: facial swelling, widespread rash, or trouble breathing.
• Symptoms of very low blood sugar if you also use insulin or a sulfonylurea.
• Pain in the upper right abdomen, fever, or yellowing skin, which can signal gallbladder disease.

Safety essentials

• The thyroid warning is absolute: never start semaglutide with a personal or family history of medullary thyroid carcinoma or MEN2, and report any neck lump, swelling, or hoarseness right away.
• Know your schedule: the injectable pens are dosed once weekly, the tablet once daily. Taking the injection more often than weekly does not help and increases side effects.
• Treat severe, persistent abdominal pain as an emergency and get it checked for pancreatitis rather than assuming it's routine nausea.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.