Semaglutide.

What semaglutide does

Semaglutide acts on a receptor for GLP-1, a hormone involved in appetite and blood-sugar regulation. It can affect insulin and glucagon signals, slow how quickly the stomach empties and influence appetite. This helps explain why it is studied and prescribed, but it does not predict the same benefit for every person or product.

For related questions, read weight-loss medicines and muscle, weight medicines and the contraceptive pill, and what “fat burning” and appetite claims mean.32

One ingredient, several products

In the United States, Ozempic is available as injections and tablets with their own labels. Rybelsus is also a semaglutide tablet. Wegovy is a separate semaglutide product approved for weight management and other specified uses.

The product, how it is taken, the people it is for and its approved uses all matter. Approvals differ by country and can change. For product differences, see the semaglutide product comparison; for storage, see the storage guide. Check the current label for your own product and country.

The US prescribing information for Rybelsus and Ozempic tablets says to take them in the morning on an empty stomach, with no more than 4 US fluid ounces (about 118 mL) of water, and swallow them whole. It says to wait at least 30 minutes before food, other drinks or other oral medicines. The two tablets are not interchangeable milligram for milligram. Follow the instructions for your own product and ask your prescriber or pharmacist before changing products or treatment.267

In March 2026, the US FDA approved Wegovy HD, a 7.2 mg semaglutide injection, for weight reduction and long-term maintenance in certain adults with obesity or overweight and a weight-related condition. The FDA said altered skin sensation, such as sensitivity, pain or burning, was reported more often at the higher dose and was under further investigation. This is a US approval for a named product, not a reason to change treatment: discuss symptoms or product questions with the prescriber and check the local label.17

What the evidence can and cannot show

Large randomised trials can estimate average effects for the people and period studied. They cannot guarantee your result, establish that an unlabelled product is safe or answer every question about long-term use. Weight, blood sugar, heart-related outcomes and side effects are different things to measure.

Explore how to read a result. For a direct weight-management trial, see tirzepatide and semaglutide in SURMOUNT-5.2

Can semaglutide reduce heart attacks and strokes?

The SELECT trial included 17,604 adults aged 45 or older with heart or blood-vessel disease and overweight or obesity, but without diabetes. They were randomly assigned injectable semaglutide or a placebo alongside their usual care. The manufacturer funded the trial.

Over about 40 months on average, researchers counted a first event in a combined measure: death from cardiovascular causes, a nonfatal heart attack or a nonfatal stroke. An event occurred in 6.5% of the semaglutide group and 8.0% of the placebo group, a difference of 1.5 percentage points. Side effects led 16.6% of the semaglutide group and 8.2% of the placebo group to stop the trial product permanently.

These group results do not predict an individual’s outcome or establish the same benefit for every semaglutide product or group of people. In 2024, the US FDA approved Wegovy injection to reduce cardiovascular risk in adults with cardiovascular disease and overweight or obesity. Labels and approved uses differ by product and country. Read how to interpret trial results and discuss prescribed treatment with a clinician.1112

What happened when semaglutide was stopped?

In STEP 4, 902 adults with obesity or overweight and a weight-related condition, without diabetes, began injectable semaglutide alongside lifestyle support. After 20 weeks, 803 who reached the study’s maintenance dose were randomly assigned to continue semaglutide or switch to placebo for 48 weeks; both groups continued lifestyle support. Compared with their weight at randomization—not their starting weight—the placebo group gained an estimated 6.9% on average, while the continuing group lost a further 7.9%. During the randomized period, the results text and safety table report gastrointestinal disorders in 41.9% continuing semaglutide and 26.1% receiving placebo. JAMA notes an abstract data-typo correction on 7 June 2023; the currently displayed abstract also gives 41.9%. During the initial 20-week period, 5.3% of the 902 participants who started treatment stopped it because of adverse events, mostly gastrointestinal. These averages do not predict one person’s experience; people unable to reach the maintenance dose were not randomized. The manufacturer, Novo Nordisk, funded the trial. Its design differs from the withdrawal study discussed in the tirzepatide profile, so the percentages are not a direct comparison between medicines. Discuss treatment changes with the prescriber.

A separate STEP 1 extension followed 327 participants who had completed the original treatment period. Among those previously assigned semaglutide, the observed average loss was 17.3% of starting weight at 68 weeks; one year after treatment stopped, the group had regained an average 11.6 percentage points of starting weight, leaving a net loss of 5.6%. Structured lifestyle support also stopped, and some participants later used weight-management medicines. This selected follow-up did not randomly compare continued treatment with stopping; it cannot predict an individual’s future weight or isolate the effect of stopping the medicine from the other changes. Novo Nordisk funded the study. Explore what happens after stopping and how to read the withdrawal trials.

If weight loss has slowed, see what a plateau can mean and what the studies measured.1016

Risks and product quality

Product labels include gastrointestinal adverse effects and warnings that need to be read with the particular product. Unapproved or compounded products may differ in concentration, sterility, storage and identity. This page provides context, not dosing or treatment advice. If you have a procedure planned, see GLP-1 medicines and anaesthesia. For pregnancy planning, unexpected exposure and breastfeeding, see GLP-1 medicines and pregnancy.

The US Wegovy label warns of reports of acute kidney injury associated with dehydration, often after nausea, vomiting or diarrhoea. It advises telling a health professional promptly if those symptoms persist. If you cannot keep fluids down, seek urgent medical advice; a clinician can assess dehydration and kidney function.

The June 2026 US Wegovy patient guide says to stop using Wegovy and get medical help immediately for signs of a serious allergic reaction, such as swelling of the face, lips, tongue or throat, or trouble breathing or swallowing. Breathing or swallowing difficulty or a suspected severe allergic reaction is an emergency: call local emergency services. Seek prompt medical advice for other concerning symptoms and check the current instructions for your exact product.

The US Wegovy label includes a boxed warning about thyroid C-cell tumours: semaglutide caused these tumours in rodents, but whether it causes them in humans is unknown. The label says Wegovy must not be used by people with a personal or family history of medullary thyroid carcinoma or with multiple endocrine neoplasia type 2 (MEN 2). It is also contraindicated after a serious allergic reaction to semaglutide or a Wegovy ingredient. This is the named US product information; discuss your personal and family history and exact product with the prescriber.

Read the evidence on hair loss and weight-loss medicines, including trial rates and possible causes.

See gallbladder risks, trial figures and when to seek care.

See what to check after a missed dose or longer break. For urgent symptoms and the separate evidence on pancreas inflammation, see GLP-1 medicines and pancreatitis.

For practical questions about appetite, meals and nausea with these medicines, see eating and drinking with semaglutide or tirzepatide.2145

Wegovy can cause low blood sugar (hypoglycaemia). The US label says the risk can be higher when semaglutide is used with insulin or medicines that stimulate insulin release, such as sulfonylureas. For people with diabetes, the label advises blood-glucose monitoring; the prescribing team may need to review the other medicines. Ask the prescriber about warning symptoms and your monitoring plan, and do not change prescribed medicines on your own.1

Sudden vision loss: what is NAION?

NAION is a condition in which reduced blood flow damages the optic nerve, which carries visual information to the brain. It can cause sudden, often painless vision loss, usually in one eye. In February 2026, the UK medicines regulator MHRA said semaglutide may very rarely be associated with NAION.

If you suddenly lose vision, including part of your vision, or your eyesight gets worse quickly, the MHRA advises urgent assessment at an eye emergency service or emergency department. Sudden vision changes can have other causes too. Do not try to diagnose the cause yourself. The regulator advises clinicians to stop semaglutide if NAION is confirmed.

Estimates and warnings differ by country. A rare association does not predict what will happen to one person. Read more about NAION, the warning and the studies.13

How is this different from diabetic retinopathy?

Diabetic retinopathy affects blood vessels in the light-sensitive tissue at the back of the eye. It is different from NAION. In SUSTAIN-6, a 104-week trial in 3,297 adults with type 2 diabetes, first retinopathy complications were recorded in 50 of 1,648 participants assigned semaglutide and 29 of 1,649 assigned placebo. The FDA review found complications were more frequent in people who already had retinopathy at baseline. The EU Ozempic information notes that rapid improvement in glucose control has been associated with temporary worsening of diabetic retinopathy, while other mechanisms cannot be excluded. These trial results concern this population and treatment setting, not the risk for every semaglutide user. If you have diabetes or existing eye disease, discuss monitoring and changes in vision with your care team; do not stop prescribed diabetes treatment without clinical advice. For the eye-trial findings and monitoring context, see the guide to diabetic retinopathy.1415

What testing of a few online products found

In a 2024 study, researchers ordered semaglutide from six selected online sellers that did not require a prescription and had been flagged by pharmacy-checking services. Only three products arrived. All three contained semaglutide, but the measured amounts were higher than their labels stated.

One sample had a high level of endotoxin, a substance associated with bacteria, suggesting possible contamination. The tests found no living microorganisms. This tiny, selected sample cannot tell us how common such problems are today or establish the quality of another seller’s product. It did not test compounded medicines from licensed pharmacies.8

Compounded, generic and counterfeit are different

In the United States, a compounded medicine may be prepared for a specific patient need. The FDA does not review each compounded product for safety, effectiveness and quality before it is marketed. An FDA-approved generic follows a different approval process.

In March 2026, the FDA warned 30 telehealth companies about misleading claims, including claims that compounded GLP-1 products were the same as approved medicines. Counterfeit products are a separate concern: they falsely claim an identity or source. Rules and ways to check products vary by country. Discuss the exact product and source with a prescriber or pharmacist. See research-labelled peptides and product quality.9

Storage and travel depend on the exact product

Instructions depend on the brand, country, form and whether the product has been opened or used. A tablet and an injection may need different storage. Check your package and the product-specific storage guide. If travelling, see travelling with refrigerated medicine. Ask a pharmacist or prescriber about your own product.

Development & regulatory context

These selected records are not a complete global legal-status list. Approval depends on the product, use, population and country; check each record’s date.