Definition
A GLP-1 receptor agonist is a medicine that switches on the same receptor as your own GLP-1 hormone, but for much longer. The result is lower appetite, lower blood sugar after meals and a slower stomach.
An agonist is a substance that activates a receptor. GLP-1 receptor agonists bind to the GLP-1 receptor in the pancreas, the gut and the brain and turn it on, the way the natural hormone does. In US pharmacies the class includes semaglutide (Ozempic, Wegovy, Rybelsus, Wegovy tablets), liraglutide (Saxenda) and orforglipron (Foundayo). Tirzepatide (Mounjaro, Zepbound) also activates the GIP receptor, so it is called a dual GIP/GLP-1 agonist.
The big difference from your own GLP-1 is time. The natural hormone lasts minutes. Liraglutide has a half-life of about 13 hours, so it is a daily shot. Semaglutide lasts about a week, so it is a weekly shot or a daily tablet. Orforglipron, a daily pill, has a half-life of about 29 to 49 hours. The labels share the same core warnings across the class: a boxed warning about thyroid C-cell tumors seen in rodents, acute pancreatitis, gallbladder disease and severe stomach and bowel side effects.
The labels also say not to combine two GLP-1 receptor agonists, or a GLP-1 with another product that contains the same drug. Stomach and bowel effects are the most common side effects for every medicine in the class, which is why GLP-1 SOS built the Lab around them.
In the Lab
- Is the GLP-1 pill worse for nausea or constipation than the shot?
- How long before a GLP-1 starts working (appetite and weight)
- Why did my GLP-1 stop working?
- Taking a GLP-1 with metformin, blood pressure or thyroid medicines
From the people behind the Lab
You do not have to figure this out alone.
GLP-1 SOS is the daily companion made for life on a GLP-1. Plain answers like this one, a support team that replies to real questions from real people, and daily formulas like GLP-1 SOS Daily Gut Relief, designed around the side effects that come with the medication. The GLP-1 Lab is our free education arm: no login, no paywall, no hype. Side effects are part of the road. Suffering through them is not.
Sources (4)
- Wegovy (semaglutide) injection and tablets, Prescribing Information. Novo Nordisk / FDA, revised June 2026.
- Saxenda (liraglutide) injection, Prescribing Information. Novo Nordisk, revised February 2026.
- Foundayo (orforglipron) tablets, Prescribing Information. Eli Lilly, revised July 2026.
- Mechanisms of Action and Therapeutic Application of Glucagon-like Peptide-1. Cell Metabolism, 2018.
Reviewed by the GLP-1 SOS editorial team · Education, not medical advice · Talk to your prescriber about your dose and your symptoms.
