Semaglutide

FDA-approved

Also known as: Ozempic, Wegovy, Rybelsus

Structure source: PubChem CID 56843331. [Aib] is aminoisobutyric acid; [K*] is a lysine carrying a fatty-acid chain through a linker.

Semaglutide is a lab-made version of GLP-1, a gut hormone, changed so that its effect lasts about a week. It is taken as a weekly injection or a daily tablet. It lowers blood sugar, appetite and body weight.

Approved for blood sugar control, with diet and exercise, in adults with type 2 diabetes (as Ozempic injection, and as Rybelsus or Ozempic tablets). In adults with type 2 diabetes, it is also approved to lower the risk of heart attack, stroke and cardiovascular death. For the injection this covers people with established cardiovascular disease; for the tablets, people at high risk. Ozempic injection is also approved for adults with type 2 diabetes and chronic kidney disease. There, it is approved to lower the risk of kidney decline, kidney failure and cardiovascular death. As Wegovy, alongside diet and exercise, it is approved for long-term weight reduction in adults with obesity, or overweight with at least one weight-related condition. The Wegovy injection is also approved for weight reduction in children aged 12 and older with obesity. Wegovy is also approved to lower the risk of heart attack, stroke and cardiovascular death in adults with established cardiovascular disease and obesity or overweight. Under accelerated approval, the Wegovy injection is also approved in adults for MASH, a fatty liver disease with inflammation, with moderate-to-advanced scarring but no cirrhosis.

How it works

It is a modified copy of human GLP-1, with two amino acids swapped and a fatty-acid chain attached.
The fatty-acid chain binds albumin, a blood protein, which slows its removal and protects it from breakdown. Its half-life is about one week.
When blood sugar is high, it raises insulin release and lowers glucagon, a hormone that raises blood sugar.
It slows stomach emptying and acts on brain areas that control appetite, so people eat fewer calories. In animal studies, it reached and activated these appetite-control brain cells.
The weight lost is more fat than lean tissue, but some lean tissue is lost too.
How it lowers heart and kidney events is not yet known.

Evidence

Weight loss in obesity

Strong human evidenceCEBM Level 1a

A 68-week trial enrolled 1,961 adults without diabetes who had obesity, or overweight with a weight-related condition. Weekly injections cut body weight by about 15% on average, versus about 2% on placebo. In a later trial, people first took it for 20 weeks. Over the next 48 weeks, people switched to placebo regained about 7% of their weight, while those who stayed on it lost about 8% more.

Type 2 diabetes; heart attack and stroke risk

Strong human evidenceCEBM Level 1b

In a 30-week trial of 388 adults with type 2 diabetes, it lowered HbA1c, a three-month average of blood sugar, by about 1.5 percentage points. Placebo had almost no effect. A larger trial enrolled 17,604 adults with established cardiovascular disease and overweight or obesity, but no diabetes. Over about three years, it lowered the combined rate of heart attack, stroke and cardiovascular death by 20%.

Treating early Alzheimer's disease

Tested: no benefit shownCEBM Level 1a

Two trials in 3,808 people with early Alzheimer's disease found that daily semaglutide tablets did not slow the disease over two years compared with placebo. No trial has been designed to test whether it prevents dementia; reanalyses of trials of this drug class give mixed results.

Caveats

Nausea, diarrhea, vomiting, constipation and belly pain are the most common side effects. They are usually temporary.
Rodent studies found thyroid C-cell tumors; whether this happens in people is unknown. It must not be used by people with a personal or family history of medullary thyroid cancer or MEN 2.
Labels also warn about pancreatitis, gallbladder disease and kidney injury from dehydration. Low blood sugar can occur when it is combined with insulin or other drugs that raise insulin release.
In people with type 2 diabetes, one trial found more diabetic eye complications (retinopathy). A rapid fall in blood sugar is the suspected cause.
Breathing stomach contents into the lungs during general anesthesia or deep sedation has been reported, so surgical teams need to know about it.
An observational study linked it to NAION, a rare optic-nerve stroke that causes sudden vision loss; the study could not prove cause. Sudden vision loss needs urgent eye care.
Weight tends to return after stopping. A year after stopping, people in one study had regained about two-thirds of the weight they had lost.
Because it lasts so long in the body, the labels advise stopping it at least two months before a planned pregnancy.

References

Reviewed by Shubham Gupta, MD — Founder & President · October 31, 2026

This page is for education only. It is not medical advice. Decisions about any treatment belong with a physician who knows your history.