Semaglutide | The Peptide Informative

Part 1Header & identifiers

Also known as: GLP-1 receptor agonist; marketed for weight management as Wegovy. Class: GLP-1 / metabolic.

Class: GLP-1 receptor agonist
Brand (weight management): Wegovy, NDA 215256
Half-life: About 1 week (SUSTAIN-6 background)
Route studied: Once-weekly subcutaneous injection

Last reviewed 3 Nov 2026 by The Peptide Informative editorial team. Found an error? Tell us; see our corrections policy.

Part 2Status at a glance

FDAApproved prescription drug. Wegovy is indicated, together with diet and physical activity, to reduce major adverse cardiovascular events in adults with established cardiovascular disease and obesity or overweight, and for long-term weight reduction in specific adult and pediatric (12+) populations (FDA label).

Boxed warningRisk of thyroid C-cell tumors seen in rodents; contraindicated with a personal or family history of medullary thyroid carcinoma or MEN 2 (FDA label).

Enforcement newsSemaglutide appeared across multiple of the August 2026 FDA warning letters to online peptide vendors (ArentFox Schiff).

SportCheck the current WADA Prohibited List.

Status checked 3 Nov 2026. Regulations changed several times in 2026, so check the linked sources for updates.

Part 3Evidence grade

Approved drug

Several large, double-blind, placebo-controlled randomized trials published in the New England Journal of Medicine, plus FDA approval.

How we grade evidence.

Part 4What it is

Semaglutide is a synthetic analog of glucagon-like peptide 1 (GLP-1), a gut hormone. It activates the GLP-1 receptor and is built for a long half-life of about one week, which is why trials give it once weekly [2].

Part 5What studies found

Weight (STEP 1)

In 1,961 adults with obesity or overweight and no diabetes, randomized 2:1 to weekly semaglutide 2.4 mg or placebo for 68 weeks (both with lifestyle intervention), mean body-weight change was −14.9% versus −2.4% with placebo. Half of the semaglutide group (50.5%) lost 15% or more, versus 4.9% on placebo [1].

Cardiovascular outcomes in type 2 diabetes (SUSTAIN-6)

In 3,297 patients with type 2 diabetes at high cardiovascular risk, the composite of cardiovascular death, nonfatal heart attack or nonfatal stroke occurred in 6.6% on semaglutide versus 8.9% on placebo over 104 weeks (hazard ratio 0.74) [2].

Cardiovascular outcomes in obesity without diabetes (SELECT)

In 17,604 adults aged 45 or older with existing cardiovascular disease and a BMI of 27 or more, the same composite outcome occurred in 6.5% on semaglutide versus 8.0% on placebo over a mean follow-up of 39.8 months (hazard ratio 0.80) [3].

Part 6Doses used in published studies

Not a recommendationThese are doses reported in published studies, listed with their population, route and duration so readers can understand the research. They are not instructions, and they say nothing about safety for you. Talk to a licensed clinician.

Study	Population	Route	Dose studied	Duration	Main result
STEP 1 [1]	1,961 adults, BMI ≥30 (or ≥27 with a weight-related condition), no diabetes	Subcutaneous, once weekly	2.4 mg	68 weeks	−14.9% vs −2.4% body weight
SUSTAIN-6 [2]	3,297 adults with type 2 diabetes at high CV risk	Subcutaneous, once weekly	0.5 mg or 1.0 mg	104 weeks	MACE 6.6% vs 8.9%
SELECT [3]	17,604 adults ≥45 with CVD, BMI ≥27, no diabetes	Subcutaneous, once weekly	2.4 mg	Mean exposure 34.2 months	MACE 6.5% vs 8.0%

For an approved drug, dosing is set by the prescriber under the FDA label [4]. The trial doses above are listed only so readers can understand the studies.

Part 7Safety & adverse events

Gastrointestinal effects: nausea and diarrhea were the most common adverse events in STEP 1, usually transient and mild to moderate. 4.5% stopped because of GI events, versus 0.8% on placebo [1].
In SELECT, adverse events led to permanent discontinuation in 16.6% on semaglutide versus 8.2% on placebo [3].
In SUSTAIN-6, diabetic retinopathy complications were more frequent with semaglutide (hazard ratio 1.76) [2].
The FDA label lists serious risks including thyroid C-cell tumors (in rodents), acute pancreatitis, acute gallbladder disease, hypoglycemia, acute kidney injury, hypersensitivity, diabetic retinopathy complications, heart-rate increase, and suicidal behavior and ideation [4].

Report side effectsSuspected side effects can be reported to FDA MedWatch.

Part 8What is unknown

The FDA label says it is unknown whether semaglutide causes thyroid C-cell tumors in humans, because the human relevance of the rodent findings has not been determined [4].
The trial results apply to the trial populations and to the approved product. They do not tell you about products bought outside the regulated supply chain, which FDA has targeted with warning letters in 2026 [5].

Part 9Community discussion

Semaglutide will have its own moderated category when our forum opens. Personal experiences there are labeled as anecdotes, and claims about research must link a source.

Join the forum waitlist

Part 10References

Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384(11):989-1002. PubMed 33567185 · doi:10.1056/NEJMoa2032183
Marso SP, et al. Semaglutide and Cardiovascular Outcomes in Patients with Type 2 Diabetes (SUSTAIN-6). N Engl J Med. 2016;375(19):1834-1844. PubMed 27633186 · doi:10.1056/NEJMoa1607141
Lincoff AM, et al. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes (SELECT). N Engl J Med. 2023;389(24):2221-2232. PubMed 37952131 · doi:10.1056/NEJMoa2307563
U.S. FDA. Wegovy (semaglutide) prescribing information and Drugs@FDA record, NDA 215256. Drugs@FDA
ArentFox Schiff. RUO-ined: Five Peptide Vendors Learn “Research Use Only” Is Not a Legal Strategy. 18 Sep 2026. afslaw.com

Educational information onlyThis profile summarizes published research. It is not medical advice and does not recommend using Semaglutide. Full medical disclaimer.