Ozempic belongs to a class of medications called GLP-1 receptor agonists (glucagon-like peptide-1 receptor agonists). Its active ingredient is semaglutide, and it works by mimicking a natural hormone your gut produces after you eat. The drug is FDA-approved for type 2 diabetes, not weight loss, though it’s widely prescribed off-label for that purpose.
How GLP-1 Receptor Agonists Work
Your intestines naturally release a hormone called GLP-1 every time you eat. This hormone signals your pancreas to produce insulin, tells your liver to stop releasing stored sugar, and slows down how fast food leaves your stomach. The problem is that natural GLP-1 breaks down within minutes, destroyed by an enzyme in your bloodstream.
GLP-1 receptor agonists like Ozempic are engineered versions of that hormone, built to resist that breakdown. A single weekly injection keeps the drug active in your body for days, continuously triggering the same receptors that natural GLP-1 would. The result is lower blood sugar after meals, reduced appetite, and slower digestion that helps you feel full longer. Importantly, the insulin-boosting effect only kicks in when blood sugar is elevated, which lowers the risk of dangerously low blood sugar compared to some other diabetes medications.
Other Drugs in the Same Class
Ozempic is one of several GLP-1 receptor agonists on the U.S. market. Others include dulaglutide (Trulicity), liraglutide (Victoza), exenatide (Byetta and Bydureon), and lixisenatide (Adlyxin). These all target the same receptor but differ in how often you take them, how they’re delivered, and what they’re approved to treat.
There’s also a newer related class called dual GLP-1/GIP receptor agonists, which activate two gut hormone receptors instead of one. Tirzepatide (Mounjaro) is currently the only drug in that category.
Three Brand Names, One Active Ingredient
Semaglutide is sold under three different brand names, each with a distinct purpose and format:
- Ozempic is a once-weekly injection approved for type 2 diabetes management. It is not FDA-approved for weight loss.
- Wegovy is also a once-weekly semaglutide injection, but it’s FDA-approved specifically for weight management in adults and children aged 12 and older. It uses higher doses than Ozempic.
- Rybelsus is a daily oral tablet of semaglutide, approved for type 2 diabetes. It must be taken on an empty stomach with only a sip of water, and you need to wait 30 minutes before eating, drinking, or taking other medications.
The distinction matters because Ozempic is frequently prescribed off-label for weight loss, even though it lacks formal FDA approval for that use. When people talk about “taking Ozempic to lose weight,” they’re using a diabetes drug for a purpose the FDA hasn’t reviewed it for, even though the same molecule at a different dose (Wegovy) does have that approval.
What Ozempic Is Approved to Treat
The FDA has approved Ozempic for three specific uses, all tied to type 2 diabetes. First, it’s approved alongside diet and exercise to improve blood sugar control. Second, it’s approved to reduce the risk of major cardiovascular events (heart attack, stroke, or cardiovascular death) in adults with type 2 diabetes who already have heart disease. Third, it’s approved to slow kidney disease progression and reduce cardiovascular death risk in adults with type 2 diabetes and chronic kidney disease.
The cardiovascular benefits are substantial. In the SELECT trial, which enrolled over 17,600 participants with obesity and established heart disease, semaglutide reduced major adverse cardiovascular events by 20% compared to placebo. Participants also lost an average of 8.5 percentage points more body weight than those on placebo.
How the Dosing Works
Ozempic is given as a once-weekly injection under the skin, typically in the abdomen, thigh, or upper arm. You start at a low dose for the first four weeks to let your body adjust. That starting dose isn’t strong enough to control blood sugar on its own; it’s purely to minimize side effects like nausea. After four weeks, the dose increases, and if blood sugar still isn’t well controlled after another four weeks, your doctor can raise it again to the maximum weekly dose.
Key Safety Considerations
Ozempic carries an FDA black box warning, the most serious type of safety alert, regarding thyroid tumors. In animal studies, semaglutide caused thyroid C-cell tumors at doses relevant to human use. Whether this happens in humans remains unknown, but people with a personal or family history of medullary thyroid carcinoma or a condition called Multiple Endocrine Neoplasia syndrome type 2 should not take the drug.
The FDA has also raised concerns about compounded and counterfeit versions of semaglutide. Compounded drugs, which are mixed by specialty pharmacies rather than manufactured by the original drugmaker, do not undergo FDA review for safety, effectiveness, or quality. The agency has received reports of adverse events potentially linked to compounded semaglutide products, including cases where doses exceeded what the approved label recommends. Counterfeit Ozempic products have also appeared in the U.S. market, and these may contain incorrect ingredients or wrong amounts of the active drug.