By Ann Czarnik, M.D., FACEP, Board-Certified Emergency Medicine Physician, Trio Concierge Medicine
One question I hear almost every week: is tirzepatide a GLP-1? The short answer is yes, and then some. The more useful answer is how it differs from semaglutide, and how to tell which one fits you.
The Short Answer
Yes. Tirzepatide works on GLP-1, the same hormone as semaglutide. It also works on a second one, called GIP. That makes it a dual-action medication, and that second pathway is the main reason the two drugs perform differently.
At a Glance
| Tirzepatide | Semaglutide | |
|---|---|---|
| How it works | Two hormones: GIP and GLP-1 | One hormone: GLP-1 |
| Brand names | Mounjaro, Zepbound | Ozempic, Wegovy, Rybelsus |
| How it is taken | Weekly injection | Weekly injection (Rybelsus is a daily pill) |
| Weight loss, side by side | About 20% | About 14% |
| Proven heart benefit | Still being studied | Yes, FDA-approved for it |
| Common side effects | Nausea, fullness, constipation, reflux | Nausea, fullness, constipation, reflux |
What These Medications Do
After you eat, your gut releases hormones that tell your body it has had enough. GLP-1 is one of them. It slows how fast your stomach empties, helps you feel full sooner and helps control blood sugar. GIP also helps with blood sugar and appears to affect how the body handles fat.
Semaglutide copies GLP-1. Tirzepatide copies both. Both are usually taken as a shot once a week.
Tirzepatide is sold as Mounjaro for type 2 diabetes and Zepbound for weight loss. Zepbound is also approved for sleep apnea in adults with obesity.5 Semaglutide is sold as Ozempic for type 2 diabetes and Wegovy for weight loss. It has been around longer, and for some patients that longer track record matters.
Which Works Better?
For weight loss, tirzepatide has the edge. In the largest study that compared the two directly, people on tirzepatide lost about 20% of their body weight over about a year and a half. People on semaglutide lost about 14%.1 For someone who weighs 220 pounds, that is roughly 44 pounds compared with 30.
For blood sugar, both work well. In people with type 2 diabetes, tirzepatide lowered blood sugar a bit more.2
For the heart, semaglutide has the stronger record. In a large study of people with heart disease and extra weight, semaglutide lowered the risk of heart attack, stroke or death from heart disease by 20%.3 The FDA has approved Wegovy for that purpose.6 Tirzepatide’s heart research is newer. So far it has matched an older GLP-1 medication, but it has not yet been shown to do better.4
What to Expect
The side effects are the same for both: nausea, feeling full quickly, constipation, diarrhea and reflux. They are usually worst in the first few weeks and after each dose increase, and they usually ease. In the side-by-side study, slightly fewer people stopped tirzepatide because of stomach trouble than stopped semaglutide.1
What I tell every patient: do not push through serious side effects to hit a number on the scale. If you cannot eat or stay hydrated, we slow down or pause. The schedule is a guide, not a contract.
A few things are worth knowing up front:
- Fast weight loss can cause gallstones.
- Severe belly pain that moves to your back can be pancreatitis and needs to be checked right away.
- Neither medication is for anyone with a personal or family history of medullary thyroid cancer or MEN 2.7
- Losing weight quickly can cost muscle too, so protein and strength training are part of the plan from day one.
Which One Is Right for You?
Stronger is not the same as right for you. Your history decides that.
Tirzepatide is often the better fit when the goal is more weight loss, when diabetes is not under control, or when semaglutide did not do enough.
Semaglutide is often the better fit when heart disease is already part of the picture, or when a patient has done well on it before.
Either can be a good start for someone trying medication for the first time. Then the choice comes down to cost, access and how your body handles it.
Not sure which one fits you? Book a visit with a Trio physician and we will go through it with you.
Wherever you start, where the medication comes from matters. If a compounded version is right for you, it should come from a state-licensed pharmacy with a prescription in your name, not a website that skips the doctor.
How We Handle It at Trio
As an emergency physician, I learned to look at the whole person before reaching for a prescription. At Trio, a board-certified physician sees you at home or by secure video, goes over your history, medications and labs, and decides with you whether a medication makes sense and which one. We start low, adjust with you and follow up. If it is not right for you, we will say so.
That is what concierge medicine is supposed to mean: a physician who knows you and is still there after the prescription. We see patients across Austin and Dallas-Fort Worth.
Common Questions
Is tirzepatide a GLP-1?
Yes. It works on GLP-1 and on a second hormone, GIP, which makes it a dual-action medication. Semaglutide works on GLP-1 alone.
Is tirzepatide stronger than semaglutide?
For weight loss, yes. In the largest side-by-side study, people lost about 20% of their body weight on tirzepatide and about 14% on semaglutide. Stronger does not always mean better for you. Your health history decides that.
What is the difference between Mounjaro and Zepbound?
Both are tirzepatide. Mounjaro is approved for type 2 diabetes. Zepbound is approved for weight loss and for sleep apnea in adults with obesity.
Does semaglutide help the heart?
Yes. In people with heart disease and extra weight, it lowered the risk of heart attack, stroke or death from heart disease by 20%. The FDA has approved Wegovy for that use.
Can I switch from semaglutide to tirzepatide?
Many people do, usually because semaglutide did not do enough or was hard to tolerate. Plan the switch with your physician, including the starting dose.
The Bottom Line
Tirzepatide is a GLP-1 medication with a second hormone added. It usually leads to more weight loss. Semaglutide has the longer record and a proven heart benefit. Both work. The real question is which one fits you, and that is a good question to bring to a physician. I would be glad to take it.
This article is general information, not medical advice for your situation. Talk with your physician before starting or stopping any treatment.
Where These Numbers Come From
- SURMOUNT-5. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity. New England Journal of Medicine, 2025. nejm.org
- SURPASS-2. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes. New England Journal of Medicine, 2021. nejm.org
- SELECT. Semaglutide and Cardiovascular Outcomes in Obesity without Diabetes. New England Journal of Medicine, 2023. nejm.org
- SURPASS-CVOT. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes. New England Journal of Medicine, 2025. nejm.org
- U.S. Food and Drug Administration. FDA Approves First Medication for Obstructive Sleep Apnea. December 20, 2024. fda.gov
- U.S. Food and Drug Administration. FDA Approves First Treatment to Reduce Risk of Serious Heart Problems Specifically in Adults with Obesity or Overweight. March 8, 2024. fda.gov
- Zepbound (tirzepatide) prescribing information, boxed warning. U.S. Food and Drug Administration. accessdata.fda.gov
Related Reading
- Medical Weight Loss in Austin and Dallas-Fort Worth
- FDA Peptides in 2026: What the July Vote Changed, and What It Did Not
- Our Services in Austin and Dallas-Fort Worth
- All Trio Articles
Ann Czarnik, M.D., FACEP is a board-certified Emergency Medicine physician and the founder of Trio Concierge Medicine, based in Austin. Trio physicians see patients in their homes and by secure video across Austin and Dallas-Fort Worth.