Important: this page is educational. Semaglutide is a prescription drug and requires a clinician evaluation.
What is semaglutide?
Semaglutide is a long-acting GLP-1 receptor agonist sold as Ozempic (for type 2 diabetes), Wegovy (for chronic weight management), and Rybelsus (an oral once-daily tablet). It mimics glucagon-like peptide-1, a gut hormone released after eating, and its half-life of roughly seven days allows once-weekly dosing.
How does semaglutide work?
Three mechanisms drive the effect. It binds GLP-1 receptors in the hypothalamus to reduce appetite and food-seeking behavior. It slows gastric emptying so meals feel larger and last longer. It enhances glucose-dependent insulin release while suppressing glucagon, which improves post-meal glucose curves. For most men the appetite shift is the most noticeable change in the first month.
For a broader overview of this drug class, read the GLP-1 101 guide.
How is semaglutide dosed?
The label titration for weight management starts at 0.25 mg weekly for four weeks, then 0.5 mg, 1 mg, 1.7 mg, and finally 2.4 mg. The slow ramp exists to manage nausea, not to delay results.
How long until semaglutide works?
Appetite usually shifts within the first week. Measurable weight loss appears by week four. Peak effect on body composition takes six to twelve months at full dose. Hemoglobin A1c reductions are visible by week eight.
Side effects of semaglutide
The most common side effects are nausea, constipation or diarrhea, reflux, and fatigue in the first month. Most resolve as the dose stabilizes or with slower titration. Less common issues include gallbladder events, dehydration, and muscle loss if protein intake is low. Pancreatitis is rare but documented.
Who should not take semaglutide?
Semaglutide is contraindicated in patients with a personal or family history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2. It is not recommended in active pancreatitis, severe gastroparesis, pregnancy, or breastfeeding. Caution is warranted in patients with a history of gallstones, kidney impairment, or eating disorders.
Semaglutide vs the alternatives
Tirzepatide is a dual GLP-1 and GIP agonist with greater weight loss in head-to-head trials but a similar side-effect profile. The choice depends on goals, tolerance, insurance, and supply.
Brand differences
Ozempic and Wegovy are the same molecule at different label doses. Ozempic is indicated for diabetes and tops out at 2 mg weekly. Wegovy is indicated for weight management and titrates to 2.4 mg weekly. Rybelsus is an oral version taken daily on an empty stomach with a small sip of water; absorption is lower so equivalent effect requires higher dosing.