Semaglutide (Ozempic, Wegovy, Rybelsus): what it is, how it works, results and side effects

What is semaglutide, and which brands is it sold as?

Semaglutide is the name of the medicine. Ozempic, Wegovy and Rybelsus are brand names for it, all made by Novo Nordisk.^1,2,3

Every medicine has two kinds of name. The medicine's own name is what works in your body. The brand is the name a company prints on the box. One medicine can have many brands.

Two brands of the same medicine can still differ. They can come at different doses, as an injection or a tablet, and be approved for different uses. A label is the official document a regulator approves for each brand. It says what the medicine is for, the doses and the warnings. On this page, "US label" means the US Food and Drug Administration (FDA) version and "EU label" means the European Medicines Agency (EMA) version.

Semaglutide's main brands. Names and approved uses vary by country.

Names only, not a recommendation. In the US, the new Rybelsus-style tablets are sold as "Ozempic tablets" (1.5, 4 and 9 mg).³

A generic is a version made by another company after the original maker's patent ends. On 21 March 2026, several companies launched generic semaglutide in India when the main Indian patent expired.¹⁹ On 28 April 2026, Health Canada approved Dr Reddy's generic version of Ozempic for type 2 diabetes. It was the first generic semaglutide approved in a G7 country.²⁰ In other countries, the patent still runs, so only the original brands are sold.

How does it work in your body?

It copies GLP-1, a hormone your gut releases after you eat. Semaglutide is 94% the same as your own GLP-1, but built to stay in your blood far longer: half of a dose is still there after about a week.^1,2

GLP-1 tells your body that food has arrived. Semaglutide switches on the same receptors (the "locks" that GLP-1 fits into), which is why it's called a GLP-1 receptor agonist.¹

Why it rarely causes low sugar on its own. The insulin and glucagon effects only switch on when blood sugar is high.² Sugar can still drop too low if you also take insulin or a sulfonylurea (sugar pills such as glimepiride or gliclazide).^1,2

Why it's taken weekly. Semaglutide sticks to albumin, a protein in your blood, which slows its removal. Its half-life (the time for half of it to leave your blood) is about 1 week.² That's why one injection a week is enough. It also means the medicine stays in your blood for about 5 weeks after the last injection, which matters for pregnancy plans and for stopping.²

Who is it for?

It depends on the brand. Ozempic and Rybelsus are approved for type 2 diabetes. Wegovy is approved for weight management, based on BMI.^1,2,3

• Type 2 diabetes (Ozempic, Rybelsus): alongside diet and exercise, to lower blood sugar.^2,3 The US Ozempic label also covers lowering the risk of heart attack, stroke and kidney decline in people with type 2 diabetes and heart or kidney disease.²
• Weight (Wegovy): on the US and EU labels, adults with a BMI of 30 or more, or 27 or more with at least one weight-related condition such as high blood pressure, prediabetes or type 2 diabetes.^1,4 BMI (body mass index) is your weight in kilograms divided by your height in metres squared.
• Heart (Wegovy): in the US, to lower the risk of heart attack, stroke and heart death in adults with heart disease and overweight or obesity.¹
• Teenagers (Wegovy injection): ages 12 and up with obesity. The EU label also requires a body weight over 60 kg (132 lb).^1,4

Lower cut-offs in Asia. Many Asian guidelines use lower BMI cut-offs than the US and EU labels. The trial of Wegovy in East Asian adults (STEP 6) used its own entry rules: BMI 35 or more with one condition, or 27 to 34.9 with two.¹ Our India guide explains India's BMI cut-offs.

These are points to start a conversation with a doctor. They don't mean you should or shouldn't take it. A doctor looks at your whole health, not only your BMI. Food and activity changes come first for everyone, and a medicine is added to them, not used instead. Surgery is an option for much higher BMIs. Our options guide compares them.

What "off-label" means

"Off-label" means using a medicine for something that isn't on its label, or at a different dose. Using Ozempic only for weight loss is off-label, because Ozempic's label covers type 2 diabetes.²

The rules differ by country. In the US, the FDA says doctors may generally prescribe an approved medicine for an unapproved use when they judge it medically right for the patient.¹⁷ For India, see what our India guide says about off-label use.

How do you take it, and at what dose?

You start low and step the dose up, usually every 4 weeks for injections or every 30 days for tablets. Going slowly lowers the risk of stomach side effects.^1,2

Solid dark box: the usual full dose. Dashed box: a higher option, not for everyone.

Injection or tablet?

Both contain semaglutide, but the doses aren't comparable. Very little of a tablet gets into your blood: about 0.4% to 1% for Rybelsus 3 to 14 mg.³ That's why tablet doses are much bigger than injection doses. The tablet carries an ingredient called SNAC that helps it get absorbed in the stomach.³

• The injection goes under the skin of your belly, thigh or upper arm, once a week, at any time of day, with or without food.²
• The tablet is taken every morning on an empty stomach, swallowed whole with up to 120 mL (4 oz) of plain water. Then wait at least 30 minutes before eating, drinking or taking other tablets.^1,3
• Brands aren't swappable mg for mg. Rybelsus and US Ozempic tablets differ, for example. Only switch on a doctor's advice.^3,6
• Never take two semaglutide products together, or semaglutide with another GLP-1 medicine.¹

The dosing details for India, including brands and prices, are in our India medicines guide.

What did the trials find?

On average, people lost about 15% of their weight on Wegovy 2.4 mg, and less if they had type 2 diabetes. Semaglutide also lowered blood sugar, and cut heart and kidney events in the people studied.

Who paid. Novo Nordisk, the maker of semaglutide, paid for STEP 1, STEP 2, SELECT, FLOW and STEP TEENS. Eli Lilly, the maker of tirzepatide, paid for SURMOUNT-5.^{7,8,12,14,15,10}

Weight

Average weight lost, as a % of body weight. Kilograms are for someone who starts at 90 kg (198 lb).

Semaglutide against tirzepatide. SURMOUNT-5 did test two medicines head to head. It compared semaglutide (Wegovy, up to 2.4 mg) with tirzepatide (sold as Mounjaro and Zepbound). Everyone knew which medicine they were on.¹⁰

All of these are averages. Some people lose much more, and some lose very little.¹

Blood sugar (type 2 diabetes)

HbA1c is a blood test that shows your average blood sugar over the past 2 to 3 months. Lower is better if you have diabetes.

How much HbA1c fell, in percentage points

In the EU, a trial called PIONEER PLUS tested the newer, higher Rybelsus tablets in 1,606 adults. After 52 weeks, HbA1c fell by 2.0 points on 50 mg and 1.5 points on 14 mg.⁶

Heart

Out of every 1,000 people, how many had a heart attack, stroke or heart-related death during the trial

Kidneys

FLOW tested Ozempic 1 mg in 3,533 adults with type 2 diabetes and chronic kidney disease, for a median of 3.4 years. It counted serious kidney events: kidney failure, a drop of half or more in kidney function, or death from kidney or heart causes.¹⁴ These happened to 187 in 1,000 people on semaglutide, against 232 in 1,000 on a dummy injection.² That's about 45 fewer in 1,000.

Teenagers

STEP TEENS tested Wegovy 2.4 mg in 201 teenagers aged 12 to 17 with obesity, for 68 weeks. Their BMI fell by 16.1% on average, against a 0.6% rise on a dummy injection.¹⁵ Gallstones affected 5 of 133 teenagers on semaglutide (about 4 in 100), and none on the dummy injection.¹⁵

What are the common side effects?

Stomach and gut effects. They're mostly mild to moderate, come during the dose steps and fade over weeks.^1,4

The cards show how many people had each one on semaglutide, and on a dummy injection. People on a dummy injection get some stomach symptoms too, so the medicine's real effect is the gap. The higher Wegovy doses cause more side effects than Ozempic's diabetes doses, so the two are shown separately.^1,2

Wegovy: US label, pooled weight trials, 2,116 adults on 2.4 mg for up to 68 weeks. Ozempic: US label, two pooled diabetes trials, about 33 weeks on average. Rounded to whole numbers. Bout lengths are medians from the EU Wegovy label.^1,2,4

In the Wegovy weight trials, 68 in 1,000 people stopped because of side effects, against 32 in 1,000 on a dummy injection.¹ On the Rybelsus 14 mg tablet, 20 in 100 felt sick, against 6 in 100 on a dummy pill.³ On the EU labels, nausea, vomiting, diarrhoea and constipation are all "very common", which means more than 1 in 10 people.⁴

If a dose step is too hard, the Wegovy label lets your doctor wait another 4 weeks before going up.¹ Don't change your dose on your own. More tips are in our side-effects guide.

What are the serious risks?

They are less common, but you should know the warning signs. Frequency words below are the EU label bands, with the number beside them.

Who shouldn't take it?

Some people shouldn't take semaglutide at all, and some need extra care. Tell your doctor about all of these before you start.

• Medullary thyroid cancer, or MEN 2In you or a close family member. MEN 2 (multiple endocrine neoplasia type 2) is a rare inherited condition that causes gland tumours.
  Don't take semaglutide. The US labels list this as a contraindication (a reason never to use it).^1,2
• Pregnant, or planning a pregnancyThere isn't enough data to use it in pregnancy.
  Stop at least 2 months before a planned pregnancy, because it stays in the body a long time. Stop if you become pregnant.^1,5
• BreastfeedingIt isn't known whether injected semaglutide passes into breast milk.
  The US label says breastfeeding isn't recommended on the tablets. For the injection, weigh it up with your doctor.¹
• Type 1 diabetesSemaglutide doesn't replace insulin.
  The EU Ozempic label says it is not a substitute for insulin, and warns about diabetic ketoacidosis in people who depend on insulin.⁵
• A past pancreatitis, or severe gastroparesisGastroparesis is a condition where the stomach empties very slowly.
  Use with caution after pancreatitis (EU label). Wegovy isn't recommended with severe gastroparesis (US label).^1,4
• Severe kidney diseaseKidney function below an eGFR of 30.
  The EU Wegovy label doesn't recommend it. Ozempic's diabetes label has no dose change for kidney disease. Your doctor decides.^4,5

Will I lose muscle?

Some of the weight you lose is lean mass, which includes muscle. Semaglutide takes off more fat than lean mass, and protein plus strength exercise help protect muscle.^1,16

Lean mass means everything that isn't fat: muscle, but also organs, bone and water. The US Wegovy label says semaglutide lowers body weight with more fat lost than lean mass.¹

A smaller appetite makes it easy to eat too little protein. A 2025 joint advisory from four US nutrition and obesity societies set out how to eat on these medicines.¹⁶

If you have kidney disease, ask your doctor before raising your protein. The right target for each person isn't settled.¹⁶

What happens when you stop?

Most people regain much of the weight. In one trial, people regained about two-thirds of what they had lost within a year of stopping.¹¹

The STEP 1 extension followed 327 people for a year after the trial ended. People on Wegovy 2.4 mg had lost 17.3% of their weight by week 68. By week 120, they had regained 11.6 percentage points, leaving them 5.6% below where they started.¹¹ Most of the improvements in heart and metabolic health measures went back towards where they began.¹¹

Another trial gave everyone Wegovy for 20 weeks, then switched some to a dummy injection. Over the next 48 weeks, people who kept taking semaglutide lost another 7.9%. People switched to the dummy injection regained 6.9%.¹

Missed doses, storage and everyday use

The rules differ between brands and between the US and EU labels. Follow the leaflet in your own pack.

If you miss a dose

• Ozempic (US label): take it as soon as you can within 5 days. If more than 5 days have passed, skip it and take the next one on your usual day.²
• Wegovy injection (US label): if your next dose is more than 2 days away, take it as soon as you can. If it's less than 2 days away, skip it.¹ The EU Wegovy label uses the same 5-day rule as Ozempic.⁴
• Missed 2 or more weekly doses in a row: the US Wegovy label says to restart at a lower dose and step up again, to lower the risk of stomach side effects.¹ Ask your doctor which dose.
• Tablets: skip the missed tablet and take the next one the following day.^1,6

Changing your injection day is allowed if the two doses are at least 2 days apart (Ozempic, US label) or 3 days apart (Wegovy, EU label).^2,4

Storing the pens

• Before first use: in the fridge at 2–8°C (36–46°F). Never freeze, and don't use a pen that has been frozen.^1,2
• Ozempic pen once in use: up to 56 days at 15–30°C (59–86°F) or in the fridge on the US label; 6 weeks below 30°C on the EU label.^2,5
• Wegovy single-dose pens: can be kept out of the fridge, up to 30°C (86°F), for up to 28 days.^1,4
• Never share a pen, even with a new needle.²

Use a different injection spot each week, even within the same area.² For hot climates and travel, see our guide to storing pens.

In your country

Brands, doses, prices and prescribing rules differ by country. We cover them country by country.

Other GLP-1 medicines: tirzepatide, liraglutide and dulaglutide.

Questions people ask