Peptide Science Desk

Is Zepbound a GLP-1? What GLP-1 really means

Zepbound is FDA approved

For weight in some adults, and for sleep apnea in adults with obesity. Prescription only.

By the Peptide Science Desk Editorial TeamFact-checked against FDA and official sources · Not yet reviewed by a licensed clinician. How we check facts

Short answer: Yes. Zepbound (tirzepatide) is a GLP-1 drug, and more. Its FDA label calls it a GIP and GLP-1 receptor agonist, so it turns on 2 gut-hormone switches. But GLP-1 is not the same as Zepbound. GLP-1 is a hormone and a group of drugs. Zepbound is one brand in that group.

GLP-1 guide: how it works, the full drugs list and side effects

Aerial view of the large brick NIH Clinical Center hospital buildings in Bethesda
The NIH Clinical Center in Bethesda, Maryland, a research hospital where many clinical trials take place.Photo: National Institutes of Health, public domain

Is Zepbound a GLP-1?

  • Yes. The Zepbound label says tirzepatide is a "GIP receptor and GLP-1 receptor agonist."
  • An agonist turns on a switch in the body. Tirzepatide turns on 2 switches: GLP-1 and GIP.
  • The label says GLP-1 helps control hunger and how much you eat. GIP is a second gut hormone. Animal and lab studies suggest it may add to that effect.
  • That is why people call Zepbound a "dual" GLP-1 drug.

Is GLP-1 the same as Zepbound?

  • No. GLP-1 is short for glucagon-like peptide-1. It is a hormone your gut makes after you eat.
  • "GLP-1 drugs" are a group of medicines that copy it. Zepbound is one brand in that group.
  • Other FDA-approved GLP-1 drugs include Wegovy and Ozempic (semaglutide), Saxenda and Victoza (liraglutide), Trulicity (dulaglutide), Byetta (exenatide) and the pill Foundayo (orforglipron).

Is Zepbound a peptide?

  • Yes. Tirzepatide is a peptide, a short chain of protein building blocks. Its label says it is built on the chain of the GIP hormone, with a few changes.
  • It has a fatty part that sticks to a protein in your blood (albumin). This makes it last longer, so it is a once-a-week shot.
  • Even the name GLP-1 has "peptide" in it.

What is Zepbound approved for?

  • To lose extra weight and keep it off, with a lower-calorie diet and more exercise. This is for adults with obesity, or adults with overweight and at least 1 weight-related health problem.
  • To treat moderate to severe obstructive sleep apnea in adults with obesity.
  • It is a prescription shot. We found no tirzepatide pill in the FDA label database (checked October 22, 2026).

How does Zepbound compare with Ozempic and Wegovy?

  • Ozempic and Wegovy contain semaglutide. It turns on only the GLP-1 switch.
  • In a 72-week head-to-head trial (SURMOUNT-5) of 751 adults with obesity, people on tirzepatide lost 20.2% of their weight, vs 13.7% on semaglutide.
  • People in that trial knew which drug they got, and the maker of tirzepatide paid for it.

What are the side effects of Zepbound?

  • The label lists nausea, diarrhea, throwing up, constipation, belly pain, upset stomach, shot-site reactions, feeling tired, allergic reactions, burping, hair loss and acid reflux as most common.
  • The label has a boxed warning: tirzepatide caused thyroid C-cell tumors in rats. It is not known if it does this in people.
  • People with a personal or family history of a thyroid cancer called MTC, or a condition called MEN 2, should not use it.
  • The label says not to use it with other tirzepatide products or any other GLP-1 drug.

Is compounded tirzepatide the same as Zepbound?

  • No. Compounded tirzepatide is mixed by a pharmacy. It is not FDA approved.
  • The FDA does not check compounded drugs for safety, quality or strength before they are sold.
  • "Not FDA approved" is not always illegal. It depends on who makes it and how it is sold. Products labeled "for research" are not medicine for people.

The numbers in charts

Head to head: tirzepatide vs semaglutide

% of starting body weight lost after 72 weeks, in the same trial

This IS a head-to-head trial: same study, same kind of people, 751 adults picked at random for one drug or the other.

Show the numbers as a table
Head to head: tirzepatide vs semaglutide: % of starting body weight lost after 72 weeks, in the same trial
DrugWeight lost
Tirzepatide (Zepbound)
Highest dose each person could take (10 or 15 mg)		−20.2%
Semaglutide (Wegovy)
Highest dose each person could take (1.7 or 2.4 mg)		−13.7%
SURMOUNT-5: 751 adults with obesity and no diabetes, 72 weeks. The trial was paid for by Eli Lilly, which makes tirzepatide. There was no placebo group. Sources: Aronne et al., NEJM 2025 (SURMOUNT-5) (PMID 40353578).

Weight loss in big obesity drug trials

% of starting body weight lost, drug vs placebo (fake shot)

Different trials, different people: not a head-to-head comparison.

Show the numbers as a table
Weight loss in big obesity drug trials: % of starting body weight lost, drug vs placebo (fake shot)
TrialDrugPlacebo
Tirzepatide 15 mg (Zepbound)
SURMOUNT-1 · 2,539 adults · 72 weeks		−20.9%−3.1%
Semaglutide 2.4 mg (Wegovy)
STEP 1 · 1,961 adults · 68 weeks		−14.9%−2.4%
Liraglutide 3.0 mg (Saxenda)
SCALE · 3,731 adults · 56 weeks		−7.4%−3.0%
Mean % change in body weight at each trial's main endpoint. The liraglutide percentages come from the Saxenda FDA label (Table 4, Study 1); the trial paper gives the number of adults and the length. Sources: Jastreboff et al., NEJM 2022 (SURMOUNT-1) (PMID 35658024); Wilding et al., NEJM 2021 (STEP 1) (PMID 33567185); Pi-Sunyer et al., NEJM 2015 (SCALE) (PMID 26132939); Saxenda FDA label, Table 4, Study 1 (DailyMed).

More charts: Peptides by the numbers

Studies in people

Big trials of tirzepatide. Both were paid for by its maker.

Study typePeopleMain findingLimits
Randomized trial: tirzepatide vs placebo (SURMOUNT-1), 20222,539 adults with obesity or overweightWeight went down 15% to 21% (by dose) vs 3.1% on placebo in 72 weeksStomach side effects were common, mostly early
Head-to-head trial: tirzepatide vs semaglutide (SURMOUNT-5), 2025751 adults with obesityWeight went down 20.2% vs 13.7% in 72 weeksPeople knew which drug they got

GLP-1 drugs at a glance

Hormone switchesPeptide?FormFDA status
Zepbound, Mounjaro (tirzepatide)GLP-1 + GIPYesWeekly shotApproved
Wegovy, Ozempic (semaglutide)GLP-1YesWeekly shot or daily pillApproved
Saxenda, Victoza (liraglutide)GLP-1YesDaily shotApproved
Foundayo (orforglipron)GLP-1No (small chemical)Daily pillApproved
RetatrutideGLP-1 + GIP + glucagonYesWeekly shot (in trials)Not approved; in testing
Check any peptide in 1 secondFree FDA Status Checker: approved, being tested, or not proven.

FAQ

Is Mounjaro a GLP-1 too?

Yes. Mounjaro is also tirzepatide, the same drug as Zepbound. Mounjaro is approved for type 2 diabetes, not for weight loss.

Is Zepbound insulin?

No. It is not insulin. The Mounjaro label says tirzepatide helps the body release more insulin when blood sugar is high.

Can I switch from Ozempic to Zepbound?

Only with your doctor. Labels say not to use 2 GLP-1 drugs together, so your doctor plans the switch.

Is there a "GLP-3" drug?

No approved one. "GLP-3" is a social media nickname for retatrutide, which turns on 3 switches and is still in testing.

Is GLP-1 the same as Zepbound?

No. GLP-1 is a hormone and a drug group; Zepbound (tirzepatide) is one brand in it that also acts on GIP.

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Sources

Not medical advice. Medical disclaimer.