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What is GLP-1? GLP-1, short for glucagon-like peptide-1, is a hormone that cells in your gut release after you eat. It tells the pancreas to release insulin when blood sugar is high, holds back glucagon, slows how fast the stomach empties and signals fullness to the brain. Natural GLP-1 lasts only a minute or two in the blood. GLP-1 medications, such as Ozempic, Wegovy, Mounjaro and Zepbound, are built to act on the same receptor for far longer. This guide explains the hormone, how GLP-1 receptor agonists work, and lists every FDA-approved GLP-1 medicine as of September 2026.
Peptide Labs does not sell any GLP-1 medication or any prescription drug. This article is general information, not medical advice. All GLP-1 medicines are prescription-only in the United States.
Key Takeaways
- GLP-1 is a gut hormone made mainly by L-cells in the lower small intestine and colon.
- The body breaks natural GLP-1 down within about 1 to 2 minutes, mostly through the enzyme DPP-4.
- GLP-1 receptor agonists are modified to resist that breakdown, so they last hours to about a week.
- FDA-approved GLP-1 medicines range from exenatide (2005) to the small-molecule pill orforglipron (2026).
- "GLP-1" supplements sold over the counter are not GLP-1 drugs and contain no GLP-1 agonist.
What is GLP-1 in the body?
GLP-1 is one of several hormones cut from a larger precursor protein called preproglucagon. According to a 2019 review in Molecular Metabolism, the precursor is made in three places: enteroendocrine L-cells spread through the gut, most densely in the last part of the small intestine (the ileum) and the colon; the pancreas, where it is mainly turned into glucagon; and a small group of nerve cells in the brainstem that are the brain’s main source of GLP-1. When food reaches the gut, L-cells release GLP-1 into the bloodstream.
Its main effects, as described in that review, are:
- Insulin release that depends on glucose. GLP-1 boosts insulin secretion when blood sugar is raised, which is why it causes little low blood sugar on its own.
- Less glucagon. It suppresses glucagon, a hormone that raises blood sugar.
- Slower stomach emptying. Food leaves the stomach more gradually.
- Fullness. It reduces food intake through signals to the brain.
The incretin effect
Scientists noticed decades ago that sugar taken by mouth triggers a much bigger insulin response than the same sugar given into a vein. This is called the incretin effect, and the gut hormones behind it are called incretins. GLP-1 is one; the other is GIP, glucose-dependent insulinotropic polypeptide. The incretin effect can be weaker in people with type 2 diabetes, which is part of why researchers turned GLP-1 into a drug target.
Why natural GLP-1 cannot be used as a medicine
Natural GLP-1 has a half-life of roughly 1 to 2 minutes. An enzyme called dipeptidyl peptidase-4 (DPP-4) clips it almost as soon as it is released, and the kidneys clear the rest. Two drug classes came from this discovery. DPP-4 inhibitors, such as sitagliptin, block the enzyme so the body’s own GLP-1 lasts a little longer. GLP-1 receptor agonists go further: they are engineered molecules that switch on the GLP-1 receptor directly and resist breakdown.
What is a GLP-1 agonist?
A GLP-1 agonist, or GLP-1 receptor agonist (GLP-1 RA), is a medicine that binds to and activates the GLP-1 receptor, producing the hormone’s effects for hours or days instead of minutes. Most are peptides, short chains of amino acids; our guide to what peptides are explains the term. The first, exenatide, is a synthetic version of exendin-4, a peptide found in the saliva of the Gila monster that shares about half its sequence with human GLP-1. Later drugs such as liraglutide and semaglutide are based on human GLP-1 with changes that protect them from DPP-4 and help them bind to albumin in the blood, which is why semaglutide can be given once a week.
Two newer approaches widen the class. Tirzepatide (Mounjaro, Zepbound) is a dual agonist that activates both the GIP and GLP-1 receptors. Orforglipron (Foundayo) activates the GLP-1 receptor but is a small molecule rather than a peptide, so it can be absorbed from an ordinary tablet. For how the two leading drugs compare, see semaglutide vs tirzepatide.
FDA-approved GLP-1 medicines at a glance (September 2026)
The table lists every GLP-1-based medicine the FDA has approved, with the year of first approval for that product and its main approved uses on the current label. T2D means type 2 diabetes; CV means cardiovascular. Availability of individual brands changes, so check with a pharmacist.
| Medicine (brand) | Active ingredient | Form | First approved | Main approved uses | Status |
|---|---|---|---|---|---|
| Byetta | Exenatide | Twice-daily injection | 2005 | Blood sugar control in adults with T2D | Brand discontinued October 2024; generic exenatide approved November 2024 |
| Bydureon, Bydureon BCise | Exenatide extended-release | Weekly injection | 2012 | Blood sugar control in T2D | Discontinued; BCise ended October 2024 |
| Victoza | Liraglutide | Daily injection | 2010 | Blood sugar control in T2D, ages 10 and up | Generic liraglutide approved December 2024 |
| Saxenda | Liraglutide | Daily injection | 2014 | Weight management in adults and ages 12 to 17 | First generic approved August 2025 |
| Tanzeum | Albiglutide | Weekly injection | 2014 | Blood sugar control in T2D | Discontinued; GSK announced the decision in 2017 |
| Trulicity | Dulaglutide | Weekly injection | 2014 | Blood sugar control in T2D; CV risk reduction in T2D | Available |
| Adlyxin | Lixisenatide | Daily injection | 2016 | Blood sugar control in T2D | Discontinued in the U.S. January 2023 |
| Soliqua; Xultophy | Insulin glargine + lixisenatide; insulin degludec + liraglutide | Daily injection | 2016 | Blood sugar control in T2D | Insulin combinations |
| Ozempic (injection) | Semaglutide | Weekly injection | 2017 | Blood sugar control in T2D; CV risk reduction; kidney risk reduction in T2D with chronic kidney disease | Available |
| Rybelsus | Semaglutide | Daily tablet | 2019 | Blood sugar control in T2D; CV risk reduction | Being replaced by Ozempic tablets |
| Ozempic tablets | Semaglutide (new formulation) | Daily tablet | 2026 (name approved February) | Blood sugar control in T2D; CV risk reduction | On sale since May 2026 |
| Wegovy (injection) | Semaglutide | Weekly injection | 2021 | Weight management, adults and ages 12+; CV risk reduction; MASH liver disease with fibrosis | Available |
| Wegovy (tablets) | Semaglutide | Daily tablet | 2025 (December) | Weight management in adults; CV risk reduction | On sale since January 2026 |
| Mounjaro | Tirzepatide (dual GIP and GLP-1) | Weekly injection | 2022 | Blood sugar control in T2D, ages 10+; CV risk reduction in T2D | Available |
| Zepbound | Tirzepatide (dual GIP and GLP-1) | Weekly injection | 2023 | Weight management in adults; moderate to severe obstructive sleep apnea with obesity | Available |
| Foundayo | Orforglipron (small molecule) | Daily tablet | 2026 (April) | Weight management in adults | Available |
A few details the table cannot hold. Liraglutide became the first GLP-1 drug with generic versions for both diabetes and weight management. Mounjaro added children 10 and older in December 2025 and a cardiovascular indication in August 2026, based on the SURPASS-CVOT trial against dulaglutide. Ozempic tablets are a newer, better-absorbed semaglutide tablet that the FDA approved under the Ozempic name in February 2026; our Ozempic pill guide explains the change. Our profiles of semaglutide, tirzepatide and liraglutide cover each molecule.
Same molecule, different brands
Several GLP-1 medications share an active ingredient but differ in approved use, strength and device, which is a common source of confusion. Ozempic and Wegovy are both semaglutide; Mounjaro and Zepbound are both tirzepatide. Each product is only FDA-approved for the uses on its own label, and the labels say not to combine products that contain the same drug or two GLP-1 receptor agonists. We compare them in Wegovy vs Ozempic and Mounjaro vs Zepbound. For oral options, see the Wegovy pill, Foundayo and why there is no tirzepatide pill.
Investigational GLP-1 drugs
Several newer drugs that act on the GLP-1 receptor, alone or with other hormone receptors, are still investigational as of September 2026, which means they are not approved and are available only in clinical trials:
- CagriSema (Novo Nordisk), a weekly combination of semaglutide and the amylin analog cagrilintide. Novo Nordisk submitted it to the FDA in December 2025.
- Retatrutide (Eli Lilly), which acts on GIP, GLP-1 and glucagon receptors. Lilly said in August 2026 that it plans to file with the FDA in early 2027.
- Orforglipron for type 2 diabetes. It is approved for weight management as Foundayo, and Lilly has submitted it in the U.S. for diabetes.
- Other candidates in trials include survodutide and mazdutide, both GLP-1 and glucagon dual agonists.
Common side effects and warnings across GLP-1 medications
Because they act on the same receptor, GLP-1 medications share much of their safety information. The most common side effects are digestive: nausea, diarrhea, vomiting and constipation, mostly while the dose is being raised. Labels warn about pancreatitis, gallbladder disease, kidney injury from dehydration, low blood sugar when combined with insulin or a sulfonylurea, serious allergic reactions and the risk of inhaling stomach contents during anesthesia. Most longer-acting GLP-1 medicines carry a boxed warning about thyroid C-cell tumors seen in rodents. Details differ by product; our guides to semaglutide side effects and tirzepatide side effects go through the labels.
GLP-1 supplements are not GLP-1 medications
Search for GLP-1 and you will also find over-the-counter products labeled “GLP-1 support” or “GLP-1 booster”. These are dietary supplements, usually built on fiber, probiotics or berberine. They contain no GLP-1 receptor agonist, are not reviewed by the FDA before sale, and cannot legally claim to act like a prescription drug. Our guide to what GLP-1 support supplements are explains what those labels mean. Products sold online as semaglutide or tirzepatide “for research use only” are not approved for use in people, and the FDA has warned consumers about them. For the wider picture, see peptides for weight loss.
Frequently Asked Questions
What is GLP-1 in simple terms?
GLP-1 is a hormone your gut releases after eating. It helps the pancreas release insulin when blood sugar is high, lowers glucagon, slows stomach emptying and makes you feel full.
What is a GLP-1 agonist?
A drug that activates the GLP-1 receptor for much longer than the natural hormone. Examples include exenatide, liraglutide, dulaglutide and semaglutide. Tirzepatide also activates the GIP receptor.
What are the GLP-1 medications for weight loss?
FDA-approved GLP-1 medicines for weight management are Wegovy (injection and tablets), Zepbound, Saxenda and its generics, and Foundayo. Ozempic, Rybelsus, Trulicity and Mounjaro are approved for type 2 diabetes, not weight management.
Is Mounjaro a GLP-1?
Mounjaro contains tirzepatide, which activates the GLP-1 receptor and also the GIP receptor, so it is usually called a dual GIP and GLP-1 receptor agonist.
Is there a GLP-1 pill?
Yes. Rybelsus, Ozempic tablets and Wegovy tablets are oral semaglutide, and Foundayo (orforglipron) is a small-molecule GLP-1 pill for weight management. There is no approved tirzepatide pill.
Are GLP-1 supplements the same as GLP-1 drugs?
No. Supplements marketed for GLP-1 support contain ingredients such as fiber or berberine, not a GLP-1 receptor agonist, and are not FDA-approved drugs.
Is a DPP-4 inhibitor the same as a GLP-1 agonist?
No. DPP-4 inhibitors such as sitagliptin slow the breakdown of the body’s own GLP-1, while GLP-1 receptor agonists activate the receptor directly and have stronger effects.
This article is general information, not medical advice. Peptide Labs does not sell prescription drugs, including any product named here. Read the Medication Guide that comes with a prescription, and ask a pharmacist or prescriber how this information applies to you.
Last reviewed September 2026.
Related guides: GLP-1 Pills: Every FDA-Approved Oral GLP-1 Compared (2026), GLP-1 Patches: What They Contain and Do They Work?, Microdosing GLP-1: What It Is, the Evidence and the Risks, GLP-1 Diet: What Experts Recommend While on GLP-1 Medicines, Liraglutide vs Semaglutide: Daily vs Weekly GLP-1 Drugs Compared, GLP-1 Side Effects: What Every GLP-1 Drug Label Warns About, Trulicity vs Ozempic: Dulaglutide and Semaglutide Compared, Hunger Hormones: How Ghrelin, Leptin and Satiety Signals Work, GLP-1 Alzheimer’s Research: What the EVOKE Trials Found, GLP-1 Drugs List: Every FDA-Approved Option in 2026.