What Is a GLP-1 Drug?

GLP-1 receptor agonists (RAs), also known as simply GLP-1 agonists, help reduce blood sugar levels and encourage weight loss. Agonist drugs work by imitating natural hormones to trigger the hormones’ effects. GLP-1 agonists:

• Prompt the pancreas to release insulin
• Prevent glucose from entering the bloodstream
• Slow down digestion to reduce glucose
• Increase feelings of fullness after eating

The effects of GLP-1 receptor agonists on insulin and glucose can help manage type 2 diabetes. These effects can also promote weight loss. Multiple GLP-1 drugs are currently on the market. They include:

• Dulaglutide (Trulicity®)
• Exenatide (Byetta®)
• Exenatide extended-release (Bydureon®)
• Liraglutide (Saxenda® and Victoza®)
• Lixisenatide (Adlyxin®)
• Semaglutide (Ozempic®, Rybelsus® and Wegovy®)

Likewise available are medications known as dual GLP-1/GIP receptor agonists, which are more powerful than pure GLP-1 RAs because they bind to both GLP-1 receptors and GIP (gastric inhibitory polypeptide) receptors. GIP is an amino acid hormone that gets released into the circulation after being stimulated by the presence of nutrients in the body. Tirzepatide, available as Mounjaro® and Zepbound®, was the only GLP-1/GIP receptor agonist on the market as of February 2025.

All GLP-1 drugs can help people shed pounds, but only certain medications are approved by the U.S. Food and Drug Administration (FDA) for weight loss. For example, Ozempic is approved to control type 2 diabetes, while Wegovy is approved for weight loss, even though the two drugs have the same active ingredient: semaglutide.

To receive FDA approval for a drug, the manufacturer must submit clinical information to the FDA showing that the medication is safe and effective for specific diseases and conditions. After a drug receives FDA approval, doctors can prescribe it for unapproved uses if they believe it’s medically suitable for a patient. A doctor might do this if there’s no approved medication to treat the patient’s condition or the patient has tried all other approved drugs without their condition improving.

How do GLP-1 drugs work?

GLP-1 drugs work by stimulating the pancreas to produce insulin and lowering blood sugar. They also slow digestion and reduce appetite to aid in weight loss. Glucose-dependent insulinotropic polypeptide, otherwise known as gastric inhibitory polypeptide or GIP, helps people lose weight by regulating blood sugar, reducing fat and keeping fat from accumulating.

GLP-1/GIP combination medications like Mounjaro and Zepbound — a tirzepatide drug — control appetite, regulate how the body utilizes fat and potentially lower the risk of type 2 diabetes as well as heart, kidney and fatty liver disease.

How do GLP-1 RAs differ from other diabetes medicines?

GLP-1 agonists differ from other diabetes medications in several important ways. While diabetes medications known as sodium-glucose cotransporter-2 (SGLT2) inhibitors reduce glucose by utilizing a protein to stop the kidneys from reabsorbing glucose, GLP-1 agonists mimic a natural hormone to help control blood sugar levels.

Research shows that while some type 2 diabetes medications can lead to weight gain, GLP-1s lower blood sugar levels and may help patients lose weight. Although GLP-1 medications could be a better option for those who want to control blood sugar and lose weight, SGLT2 inhibitors may be a safer choice for diabetics with heart or kidney problems.

What companies produce GLP-1 drugs?

Companies developing and producing GLP-1 drugs include Novo Nordisk and Eli Lilly. Novo Nordisk is the manufacturer of semaglutide medications Ozempic, Rybelsus and Wegovy, and liraglutide drugs Saxenda and Victoza. Eli Lilly manufactures tirzepatide medications Mounjaro and Zepbound, and dulaglutide drug Trulicity.

The GLP-1 drugs are medically approved to treat several conditions. Ozempic (active ingredient semaglutide) and Mounjaro (active ingredient tirzepatide) are FDA-approved to treat type 2 diabetes. The FDA has approved Wegovy (active ingredient semaglutide) and Zepbound (active ingredient tirzepatide) to help people lose weight. In 2024, Wegovy was also approved to treat heart disease in obese patients. The GLP-1 medication Saxenda (active ingredient liraglutide) is approved to treat obesity.

Research indicates that GLP-1 drugs help people lose weight by slowing stomach emptying and making people feel fuller after eating. Studies show that people taking GLP-1s may tend to have fewer cravings for dairy, starchy, salty and spicy foods, and they generally eat less.

However, taking certain GLP-1 drugs off-label for weight loss poses some risks since not all of these medications haven’t gone through the FDA’s review for safety and effectiveness for weight loss. The GLP-1 drugs approved for weight loss are approved for obese individuals, meaning those with a body mass index (BMI) of 30 or higher, or those with a related health condition like hypertension. Prescribing them off-label to those who don’t meet these criteria may create health risks.

Common side effects of GLP-1 drugs include gastrointestinal conditions like diarrhea, nausea, vomiting and reduced appetite. Severe complications, including pancreatitis and thyroid cancer, have also been linked to GLP-1 drugs.

Bear in mind that not all medications with the same active ingredient include the same side effects on their label. For example, although Ozempic and Wegovy are both semaglutide medications, the Wegovy Warnings and Precautions label lists “Heart Rate Increase” and “Suicidal Behavior and Ideation” while the Ozempic label doesn’t.

The FDA has issued warnings about the risks associated with using GLP-1 medications. The agency recently updated the labeling on several GLP-1 drugs, including all the approved GLP-1 drugs for weight loss, to include a warning about the risk for “pulmonary aspiration during general anesthesia or deep sedation.” The drugs required to carry the warning include:

• Liraglutide (Saxenda and Victoza)
• Semaglutide (Ozempic, Rybelsus and Wegovy)
• Tirzepatide (Mounjaro and Zepbound)

Ongoing legal action involving the side effects of GLP-1 drugs is also pending.

People are filing lawsuits against Novo Nordisk and Eli Lilly related to GLP-1 drugs. The lawsuits allege harm related to specific, unlisted side effects of these medications.

These side effects may include:

• Non-arteritic anterior ischemic optic neuropathy (NAION)
• Severe gastrointestinal issues, such as ileus and gastroparesis
• Deep vein thrombosis (DVT)
• Necrotizing pancreatitis
• Pulmonary embolisms

Our medical attorneys have represented thousands of patients seriously hurt by dangerous prescription medications, including GLP-1 drugs. If you believe a GLP-1 RA medication made you sick or harmed you, our medical drug attorneys have the resources needed to thoroughly investigate your potential claim and review your legal options.

Read more about our medical drug experience.

Do not stop taking a prescribed medication without first consulting your doctor. Discontinuing a prescribed medication without your doctor’s advice can result in injury or death. Adlyxin, Bydureon, Byetta, Mounjaro, Ozempic, Rybelsus, Saxenda, Trulicity, Victoza, Wegovy, and Zepound remain approved by the U.S. Food and Drug Administration.