A once-weekly GLP-1 receptor agonist approved for type 2 diabetes, obesity, heart risk, kidney disease and fatty liver disease.
Also called Ozempic, Wegovy, Wegovy HD, Wegovy tablets, Rybelsus, Ozempic tablets, NN9535, NN9536
Semaglutide is a modified copy of GLP-1, a hormone your gut releases after a meal. The natural hormone lasts about two minutes in the blood. Semaglutide has a fatty acid tail that sticks to albumin, so one injection lasts about a week. It is sold by Novo Nordisk as Ozempic (type 2 diabetes), Wegovy (weight, heart risk and fatty liver) and as daily tablets (Rybelsus, Ozempic tablets and Wegovy tablets).
The weight data are large and consistent. In STEP 1, 1,961 adults without diabetes lost an average of 14.9% of body weight over 68 weeks on 2.4 mg weekly, against 2.4% on placebo. The higher 7.2 mg dose (Wegovy HD, approved March 2026) averaged 18.7% in STEP UP. Outcome trials go past the scale: SELECT cut heart attack, stroke and cardiovascular death by 20% in 17,604 people with heart disease and excess weight, and FLOW cut serious kidney events by 24% in people with type 2 diabetes and kidney disease.
The main costs are nausea, vomiting, diarrhea and constipation, mostly during dose increases, plus gallbladder disease and rare pancreatitis. Weight comes back when the drug stops: in the STEP 1 extension, people regained about two thirds of the lost weight within a year. Semaglutide is an approved prescription drug, so the questions worth asking are about fit, side effects and how long to stay on it, not whether it works.
What it binds to, and what happens inside the body after that, step by step.
Semaglutide binds and activates the GLP-1 receptor on pancreatic beta cells, in the stomach and in appetite centers of the brainstem and hypothalamus. It raises insulin and lowers glucagon only when blood sugar is elevated, which is why it rarely causes low blood sugar on its own. It slows stomach emptying and lowers appetite and food cravings, so people eat less without trying to.
Human results and animal results are kept apart below. A result in rats tells you a mechanism is plausible. It does not tell you what happens in a person.
This is one of the best-studied drugs in medicine. Large placebo-controlled trials show average weight loss of about 15% at 2.4 mg and about 19% at 7.2 mg, fewer heart attacks and strokes (SELECT), slower kidney decline (FLOW), better heart failure symptoms (STEP-HFpEF) and resolution of fatty liver inflammation (ESSENCE). What is not shown in humans: protection against Alzheimer's disease (the EVOKE trials were negative in 2025) or any effect on aging itself.
1,961 adults with obesity or overweight, no diabetes
Average weight change at 68 weeks was -14.9% on semaglutide 2.4 mg vs -2.4% on placebo; 50.5% lost at least 15% of their weight.
Read the study17,604 adults with heart disease and BMI 27 or higher, no diabetes
Heart attack, stroke or cardiovascular death occurred in 6.5% on semaglutide vs 8.0% on placebo over about 40 months (hazard ratio 0.80).
Read the study3,533 adults with type 2 diabetes and chronic kidney disease
Serious kidney events or kidney or cardiovascular death were 24% lower on semaglutide 1 mg, and death from any cause was 20% lower.
Read the study1,407 adults with obesity, no diabetes
Average weight change was -18.7% on 7.2 mg vs -15.6% on 2.4 mg and -3.9% on placebo at 72 weeks.
Read the study800 adults with MASH and F2 to F3 liver fibrosis (interim analysis)
Liver inflammation resolved without worse fibrosis in 62.9% on semaglutide 2.4 mg vs 34.3% on placebo at 72 weeks.
Read the study529 adults with HFpEF and obesity
Heart failure symptom score improved 16.6 points vs 8.7 on placebo, and 6-minute walk distance rose 21.5 m vs 1.2 m.
Read the study803 adults who had lost 10.6% on semaglutide over 20 weeks
Those kept on semaglutide lost a further 7.9%, while those switched to placebo regained 6.9% over the next 48 weeks.
Read the study307 adults with obesity or overweight
Daily 25 mg tablets produced -13.6% weight change vs -2.2% on placebo at 64 weeks.
Read the studyNo preclinical studies are listed as key studies here. The human data above carries the evidence.
These are questions the published research has not answered.
Prescription-only drug with FDA, EMA and many other approvals. Not on the WADA Prohibited List; WADA has tracked semaglutide in its Monitoring Program since 2024 and, from January 1, 2026, monitors semaglutide and tirzepatide markers in and out of competition. In early 2026 FDA had the suicidal behavior and ideation warning removed from the Wegovy label. The EMA safety committee concluded in June 2025 that NAION, a sudden optic nerve stroke, is a very rare side effect.
How much of Semaglutide is left after a single dose
Simple first-order model from the published half-life. Real clearance varies with dose, route, kidney and liver function and formulation. This is not a dosing schedule.
This table records the doses that trials and approved labels used, with the source for each row. It is a record of research, not a recommendation, and it is open to free members.
Which symptoms are expected and which mean stop and get help: side effects and red flags.
Tap a claim to see what the studies found.
It causes thyroid C-cell tumors in rats and mice, which is why the label carries a boxed warning and excludes people with MTC or MEN 2. Large human trials and registries have not shown a clear increase, but rare cancers take years to detect, so the question is not closed.
Most people regain a large share. In the STEP 1 extension, people regained about two thirds of their lost weight within a year of stopping and most heart risk markers drifted back toward baseline. Some people kept part of the loss, but stopping without a plan usually means regain.
Lean mass made up roughly 40% of the weight lost in the STEP 1 body-scan subgroup, so most of the loss was fat. That share sits at the high end of what is reported for diet-only weight loss. Lean mass includes water and organs, not just muscle. Resistance training and enough protein are the standard ways to limit muscle loss.
Compounded products are not FDA-reviewed for identity, strength or purity, and some used semaglutide sodium or acetate salts, which FDA says are different active ingredients. FDA has logged dosing errors and adverse events tied to compounded versions.
FDA and EMA reviews of trial and real-world data did not find a causal link, and in early 2026 FDA removed the suicidal behavior warning from the Wegovy label. Anyone with mood changes on any drug should still tell their clinician.
The phase 3 EVOKE and EVOKE+ trials of oral semaglutide in 3,808 people with early Alzheimer's disease found no slowing of decline versus placebo over 104 weeks (results announced in 2025, published in the Lancet in 2026).
These pairings come up often. Almost none have been tested together in a trial, and the evidence note on each says so plainly.
Amylin and GLP-1 reduce appetite through different brain circuits, so adding the amylin analog cagrilintide was designed to add weight loss beyond semaglutide alone.
EvidenceStudied in phase 3. In REDEFINE 1, 3,417 adults lost 20.4% on the combination vs 3.0% on placebo at 68 weeks. In REDEFINE 4 it did not match tirzepatide 15 mg. Filed with FDA in December 2025; not approved as of October 2026.
Sometimes discussed online as a way to push weight loss further.
EvidenceNever studied together. Both labels say not to combine products that act on the GLP-1 receptor; overlapping drugs raise GI and dehydration risk with no shown benefit.
Not applicable: approved semaglutide is supplied as a ready-to-use solution in pens or syringes, or as tablets.
Pens and syringes: refrigerate at 36 to 46 F (2 to 8 C) before first use, never freeze, protect from light. Single-dose Wegovy pens may be kept at 46 to 86 F for up to 28 days; Wegovy FlexTouch pens up to 56 days after first use. Tablets: room temperature in the original bottle, away from moisture.
One email when a trial reads out, a label changes or the FDA acts on a peptide. Free, no selling of peptides, unsubscribe any time.