Semaglutide: how it works and the products that contain it

Ask what semaglutide is and you'll get a brand name back: Ozempic, Wegovy, Rybelsus. They're all the same molecule, made by Novo Nordisk, in different doses, devices and labels. This page is about the molecule itself: how it works, what it has done in trials, and how the products differ.

Semaglutide works by copying a gut hormone

Semaglutide copies GLP-1, a hormone your gut makes after meals. The label describes it as a GLP-1 analog with 94% sequence similarity to the human hormone that “selectively binds to and activates the GLP-1 receptor” ^[1]. Natural GLP-1 lasts minutes in the blood. Semaglutide binds to albumin, a blood protein, and resists the enzyme that breaks GLP-1 down, so one dose lasts about a week.

1. Insulin, but only when needed. It raises insulin and lowers glucagon “in a glucose-dependent manner,” so the effect is strongest when blood sugar is high ^[2].
2. Slower stomach emptying. Food leaves the stomach more slowly, so sugar enters the blood more gradually after meals.
3. Less appetite. GLP-1 receptors sit in brain areas that regulate appetite, and in animal studies semaglutide reached and activated those areas ^[1].
4. Fewer calories. The net result, in the label's words: semaglutide “decreases calorie intake.”

Those four steps explain both of semaglutide's jobs. Steps 1 and 2 lower blood sugar, which is what Ozempic is for. Steps 3 and 4 lower body weight, which is what Wegovy is for.

One molecule, five approved products

Semaglutide is the ingredient. Ozempic and Wegovy are two products made from it, with different labels, doses and devices, and the same goes for the tablets. Is semaglutide the same as Ozempic? Same drug, yes. Same product, no.

Is semaglutide the same as Wegovy? Again, same drug, different product. Wegovy's weekly doses go higher than Ozempic's (up to 7.2 mg vs 2 mg), and its label covers people without diabetes. The tablets have their own guide, our page on oral semaglutide.

Which semaglutide product is right for you? That's a label question first. Type 2 diabetes points to Ozempic or the tablets. Weight management or heart-risk reduction without diabetes points to Wegovy. A preference for a pill over a shot narrows it further. Our Ozempic vs Wegovy comparison sets the two injections side by side.

Semaglutide is approved for six uses, split across the brands

Across its brands, semaglutide carries six approved uses. Three are in type 2 diabetes: blood sugar, heart risk and kidney decline. The other three are for adults with obesity or overweight, with or without diabetes: weight, heart risk and a fatty-liver disease called MASH ^{[2] [1]}.

Can you take semaglutide without diabetes? Yes, as Wegovy, which is labeled for people with or without diabetes. Ozempic's label is type 2 diabetes only, so using it for weight alone is off-label.

Trials showed about 15% weight loss and fewer heart, kidney and liver events

In STEP 1, adults without diabetes on semaglutide 2.4 mg a week lost 14.9% of their weight over 68 weeks, against 2.4% on placebo, and half lost 15% or more ^[12]. In SELECT, 17,604 adults with heart disease and overweight had 20% fewer heart attacks, strokes and cardiovascular deaths on semaglutide ^[14].

The newest dose has its own numbers. FDA added the 7.2 mg Wegovy HD dose after two 72-week trials that the label calls Studies 8 and 9. In adults with obesity and no diabetes, weight fell 18.8% on 7.2 mg, 15.5% on 2.4 mg and 3.9% on placebo ^[1]. The higher dose also brought more dysesthesia, an odd skin sensation such as tingling or burning: 22% on 7.2 mg against 6% on 2.4 mg.

The stopping result is the one most people don't hear. A year after STEP 1 participants came off semaglutide and the trial's lifestyle program, they had regained about two-thirds of the weight they'd lost, and blood pressure and other risk factors drifted back toward where they started ^[13]. Semaglutide works while you take it.

Semaglutide causes weight loss mainly by cutting appetite

Semaglutide leads to weight loss because people eat less. The Wegovy label says it “decreases calorie intake,” that “the effects are likely mediated by affecting appetite,” and that it “lowers body weight with greater fat mass loss than lean mass loss” ^[1]. It also delays stomach emptying, which helps people feel full sooner.

Does semaglutide burn fat? Not in the way the phrase suggests. Neither label describes a fat-burning action. Fat is lost because calorie intake drops, and some lean mass is lost along with it, as with any large weight loss. In practice, the trial numbers above are what the appetite effect adds up to: about 15% of body weight on the 2.4 mg injection over 68 weeks.

That mechanism also explains the side effects. The same slowed stomach that keeps you full is behind much of the nausea, especially as doses rise. And because the drug works on appetite rather than changing your metabolism for good, the appetite comes back when you stop.

Most side effects are stomach-related, and all semaglutide brands share a boxed warning

Every semaglutide product carries a boxed warning about thyroid C-cell tumors seen in rodents, and none is for people with a personal or family history of medullary thyroid carcinoma or MEN 2. The common side effects are gastrointestinal. On Wegovy 2.4 mg, 73% of people reported stomach side effects against 47% on placebo, mostly while the dose was rising ^[1].

The labels also warn about pancreatitis, gallbladder disease, low blood sugar with insulin or sulfonylureas, kidney injury from dehydration, allergic reactions, a faster heart rate and aspiration during anesthesia. In type 2 diabetes, SUSTAIN-6 found more diabetic eye complications on semaglutide (hazard ratio 1.76) ^[17]. In STEP 1, stomach side effects led 4.5% of people to stop, against 0.8% on placebo ^[12]. Brand-specific detail is in Wegovy side effects and Ozempic safety and side effects.

There is no generic semaglutide on sale yet

Semaglutide is itself the generic name; Ozempic and Wegovy are brand names. Right now, no generic semaglutide is approved for sale in the US. FDA gave one company's generic injection, in Ozempic's pen strengths, a tentative approval on April 7, 2026 ^[4]. A tentative approval means FDA found the product meets its standards but it can't be marketed yet, usually because of patents or exclusivity.

So anything sold today as “generic semaglutide” is either the brand under another name or a compounded product. Compounded semaglutide is not a generic.

Compounded semaglutide is a pharmacy-made copy, not an approved drug

Compounded semaglutide isn't FDA-approved, FDA doesn't review it for safety or effectiveness, and FDA doesn't check its quality before it ships ^[9]. During the shortage, pharmacies could make copies widely. FDA declared the shortage over on February 21, 2025, and the grace periods for compounders ended that spring ^[8]. Compounding now has to fit narrow, patient-specific rules.

FDA has received 990 reports of adverse events tied to compounded semaglutide as of May 31, 2026, and says salt forms such as semaglutide sodium have no known lawful basis for compounding ^[9]. Our guides cover compounded semaglutide, whether it will be banned and how it compares with Ozempic.

Tirzepatide produced more weight loss head to head; liraglutide produced less

Head to head, tirzepatide beat semaglutide on weight: −20.2% vs −13.7% at 72 weeks in SURMOUNT-5, an open-label trial funded by Eli Lilly, tirzepatide's maker ^[19]. Against the older daily drug liraglutide, semaglutide won: −15.8% vs −6.4% at 68 weeks in STEP 8, a trial with Novo Nordisk authors, whose company makes both drugs ^[20].

See semaglutide vs tirzepatide for the full comparison, and our tirzepatide and liraglutide pages for each drug on its own.

Brand semaglutide costs $149 to $499 a month from the maker

Brand semaglutide's self-pay price depends on the product. Through NovoCare right now, the Wegovy pen is $349 a month, Wegovy HD is $399, the Wegovy pill is $149 to $299 by dose, and Ozempic is $349 to $499 ^{[10] [11]}. New patients pay $199 for their first two pen fills at the lowest doses, through December 31, 2026.

Compounded semaglutide from online programs runs $75–$349 a month across 72 programs. A few examples, with their pharmacy policy:

Also offered by (no standing monthly price published): Midi Health.

For the full picture, read what compounded semaglutide costs and what Wegovy costs, or see every program scored on the compounded semaglutide board and, for pills, the GLP-1 pill programs board.

Every form of semaglutide needs a prescription

Every semaglutide product needs a prescription, brand or compounded. Your own clinician can write it and send it to a local pharmacy or NovoCare Pharmacy. Telehealth programs also prescribe both brand and compounded versions after an online intake. If you're thinking about very small doses, our GLP-1 microdosing guide explains what hasn't been tested.