GLP-1 Drugs Explained: Types, Benefits, Risks and Weight Loss

GLP-1 drugs are medicines that copy a gut hormone called glucagon-like peptide-1. They lower blood sugar, slow digestion and quiet hunger, which is why they're used for type 2 diabetes and, at higher doses, for weight loss. The best-known are semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). In 2026 the class also includes daily pills: the Wegovy pill and Foundayo.

This guide covers the main types, how they work, how much weight people lose, the common risks, and how to tell them apart.

Tirzepatide also activates a second hormone receptor, GIP, so it's technically a dual agonist. Next in line is retatrutide, which adds a third (glucagon); it isn't approved yet.

Natural GLP-1 lasts a couple of minutes in the blood. The drugs are modified to last about a week (injections) or a day (pills). That's why they have such strong, steady effects. For how Wegovy specifically works, see Wegovy vs Ozempic.

The most common side effects are nausea, diarrhea, vomiting and constipation, mostly while the dose is going up. Less common but serious risks include pancreatitis, gallbladder problems, kidney injury from dehydration and low blood sugar when combined with insulin or sulfonylureas. Most injectables carry a warning about thyroid C-cell tumors seen in rodents and shouldn't be used by people with a personal or family history of medullary thyroid cancer or MEN 2. Muscle can be lost along with fat, so protein and strength training matter. See our side-effects guide.

The right drug depends on your diagnosis, how much weight you need to lose, whether you prefer a pill or an injection, and what your insurance covers. People with type 2 diabetes usually start on Ozempic or Mounjaro; people without diabetes on Wegovy or Zepbound. Our which GLP-1 is best guide compares them in detail, and our cost guide covers prices.

Be cautious with compounded or "research" versions sold online: they aren't FDA-approved and dosing errors have caused hospitalizations. See microdosing and compounded GLP-1s.

If you want the organ-by-organ version for one drug, our guide to what Wegovy does follows semaglutide from the brain to the stomach, pancreas, heart and liver.

GLP-1 drugs mimic a natural gut hormone to reduce appetite and improve blood sugar. The approved options now range from weekly injections producing about 15% to 21% weight loss to daily pills producing about 11% to 14%. They work only while you take them, so they're long-term treatments; see what happens when you stop.