Semaglutide: research, legal status and who sells it

What it is

Semaglutide is a glucagon-like peptide-1 (GLP-1) receptor agonist with an extended half-life of about one week [18]. It is the active ingredient in three FDA-approved prescription medicines: Ozempic, Rybelsus and Wegovy [1][2][3].

Research status

Semaglutide is backed by large randomized trials. In STEP 1, adults with overweight or obesity and no diabetes who took semaglutide alongside a lifestyle program lost an average of 14.9% of body weight over 68 weeks, compared with 2.4% on placebo [19]. In SELECT, which enrolled 17,604 people with cardiovascular disease and overweight or obesity but no diabetes, semaglutide lowered the rate of cardiovascular death, heart attack or stroke from 8.0% to 6.5% over roughly 40 months [20]. In type 2 diabetes, the SUSTAIN-6 trial also found fewer major cardiovascular events, but significantly more diabetic eye (retinopathy) complications [18]. Nausea and diarrhea are the most common side effects [19]. In a head-to-head obesity trial, tirzepatide produced more weight loss than semaglutide [21].

Regulatory status

Semaglutide is a prescription medicine in every market we track [1][5][6][9][13]. The FDA approved Ozempic in 2017, Rybelsus in 2019, Wegovy injection in 2021 and Wegovy tablets in December 2025 [1][2][3][4]. The EU authorized Ozempic in 2018, Rybelsus in 2020 and Wegovy in 2022 [6][7][8]. In Canada, a generic semaglutide injection has been marketed since May 2026 [12]. Semaglutide is not named on WADA’s 2026 Prohibited List [17].

Quality and testing considerations

Unapproved semaglutide has a documented quality problem. The FDA warns that unapproved versions do not undergo its review for safety, effectiveness or quality [22], and it has issued warning letters to websites selling semaglutide labeled “research use only” while promoting it for human use [23]. In a 2024 test-purchase study of illegal online sellers, every vial that arrived contained endotoxin, and measured purity was far below the 99% printed on the labels [24]. Counterfeit Ozempic pens have also reached the legitimate US supply chain, most recently in late 2025 [25]. The 2024 study’s method is a useful benchmark for what a credible test covers: content and purity by liquid chromatography–mass spectrometry, plus sterility and endotoxin testing [24].

Where it’s sold

Semaglutide is legally sold only as prescription medicines; the tables below track unapproved “research” listings and their prices.