Peptide Science Desk

GLP-1: what it is, how it works, and the full drugs list

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: GLP-1 is a hormone your gut makes after you eat. It tells your brain you are full and helps control blood sugar. GLP-1 drugs, like Ozempic, Wegovy and Zepbound, copy this hormone. They are FDA approved for type 2 diabetes, weight loss and some other uses, with a prescription.

What is GLP-1?

GLP-1 stands for glucagon-like peptide-1. It is a hormone. Your gut makes it after you eat a meal.

When people say "GLP-1" today, they often mean the GLP-1 drugs: medicines like Ozempic, Wegovy, Mounjaro and Zepbound. These drugs copy the natural hormone, but they last much longer in your body.

The first GLP-1 drug was approved in 2005 for type 2 diabetes. Today, some are also approved for weight loss.

How does GLP-1 work?

You eat. Your gut sends out GLP-1. It does 3 main jobs:

  1. 1. Brain: "I'm full"It tells your brain you have had enough, so you feel less hungry.
  2. 2. Pancreas: more insulinIt tells your pancreas to let out insulin, which helps sugar leave your blood.
  3. 3. Stomach: slow downIt slows how fast food leaves your stomach, so you stay full longer.

Your own GLP-1 is gone in about 1 to 2 minutes, because the body breaks it down fast. GLP-1 drugs are built to last much longer, so many are taken only once a week.

Semaglutide (Ozempic, Wegovy) is about 94% the same as your own GLP-1, says its FDA label. Tirzepatide (Mounjaro, Zepbound) also acts on a 2nd gut hormone, called GIP. Read Is Zepbound a GLP-1?

Is GLP-1 a peptide?

Yes. Natural GLP-1 is a peptide: a short chain of about 30 amino acids. Most GLP-1 drugs are peptides too, like semaglutide, tirzepatide, liraglutide and dulaglutide.

But not every peptide is a GLP-1. BPC-157, TB-500 and other "wellness" peptides do not work like GLP-1 drugs. And one new GLP-1 drug, Foundayo (orforglipron), is not a peptide. It is a small chemical pill.

More: Peptides vs GLP-1: what's the difference? and What are peptides?

GLP-1 drugs list: brand names and FDA status

We rate FDA status, proof and safety data on their own. They answer different questions.

GLP-1 drugHow takenFDA approved forOur ratings
Ozempic, Wegovy, RybelsussemaglutideWeekly shot or daily pillType 2 diabetes (Ozempic, Rybelsus). Weight loss, lowering heart attack and stroke risk, and a liver disease called MASH (Wegovy).FDA: ApprovedProof: StrongSafety data: Well studied
Mounjaro, ZepboundtirzepatideWeekly shotType 2 diabetes (Mounjaro). Weight loss and sleep apnea in adults with obesity (Zepbound). Also acts on a 2nd hormone, GIP.FDA: ApprovedProof: StrongSafety data: Well studied
Victoza, SaxendaliraglutideDaily shotType 2 diabetes (Victoza). Weight loss (Saxenda). Generic copies are FDA approved too.FDA: ApprovedProof: StrongSafety data: Well studied
TrulicitydulaglutideWeekly shotType 2 diabetes. Also lowers heart risk in some adults with diabetes.FDA: ApprovedProof: StrongSafety data: Well studied
ByettaexenatideShotType 2 diabetes. The first GLP-1 drug, approved in 2005.FDA: ApprovedProof: StrongSafety data: Well studied
Foundayoorforglipron · not a peptideDaily pillWeight loss. It acts on GLP-1 but is NOT a peptide. It is a small lab-made chemical.FDA: ApprovedProof: StrongSafety data: Well studied

The FDA also lists Adlyxin (lixisenatide) and 2 GLP-1 + insulin combos, Soliqua and Xultophy, for type 2 diabetes.

GLP-1 drugs still in testing (not FDA approved)

DrugWhat it isOur ratings
RetatrutideEli Lilly shot that acts on GLP-1, GIP and glucagon. Some people online call it "GLP-3."FDA: In testingProof: StrongSafety data: Limited
SurvodutideActs on GLP-1 and glucagon. From Boehringer Ingelheim and Zealand Pharma.FDA: In testingProof: StrongSafety data: Limited
MazdutideActs on GLP-1 and glucagon. Sold in China, not approved in the US.FDA: In testingProof: SomeSafety data: Limited
CagriSema (cagrilintide + semaglutide)A mix of semaglutide and an amylin drug. The maker sent it to the FDA in December 2025.FDA: In testingProof: StrongSafety data: Limited

Not approved does not mean these drugs fail. It means the FDA has not finished checking them. Today, you can only get them legally in a clinical trial. Check any name with our FDA status checker.

GLP-1 drugs: approval timeline

  1. 2005Byetta (exenatide): the first GLP-1 drug, for type 2 diabetes
  2. 2010Victoza (liraglutide), for type 2 diabetes
  3. 2014Trulicity (dulaglutide) for diabetes, and Saxenda (liraglutide), the first GLP-1 for weight loss
  4. 2016Adlyxin (lixisenatide), plus 2 GLP-1 + insulin combos: Soliqua and Xultophy
  5. 2017Ozempic (semaglutide) and Bydureon BCise (exenatide), both weekly shots
  6. 2019Rybelsus (semaglutide): the first GLP-1 pill
  7. 2021Wegovy (semaglutide) for weight loss
  8. 2022Mounjaro (tirzepatide): the first drug to act on GLP-1 and GIP
  9. 2023Zepbound (tirzepatide) for weight loss
  10. 2026Foundayo (orforglipron): a daily GLP-1 pill that is not a peptide (April 1)

Years from the FDA's own table of approved GLP-1 drugs and its April 1, 2026 Foundayo announcement.

Do GLP-1 drugs work?

Yes, for their approved uses. They were tested in big trials with a placebo (fake medicine) group.

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).

In the only big head-to-head test, people on tirzepatide lost about 20% of their weight vs about 14% on semaglutide. See Semaglutide vs tirzepatide.

Some GLP-1 drugs also help the heart, not just weight:

Fewer heart attacks, strokes and heart deaths

% of people who had one of these, drug vs placebo, in 2 big heart trials

Different trials and different people. Lower is better.

Show the numbers as a table
Fewer heart attacks, strokes and heart deaths: % of people who had one of these, drug vs placebo, in 2 big heart trials
TrialDrugPlacebo
Semaglutide 2.4 mg (Wegovy)
SELECT · 17,604 adults with heart disease and extra weight, no diabetes · about 40 months		6.5%8.0%
Dulaglutide (Trulicity)
REWIND · 9,901 adults with type 2 diabetes		12.0%13.4%
Main result of each trial: heart attack, stroke, or death from heart causes. In SELECT, 20% fewer people had one (hazard ratio 0.80). Sources: Lincoff et al., NEJM 2023 (SELECT) (PMID 37952131); Gerstein et al., Lancet 2019 (REWIND) (PMID 31189511).
  • Zepbound is approved to treat moderate to severe sleep apnea in adults with obesity.
  • Wegovy is approved for a liver disease called MASH with liver scarring.
  • Results are averages. Some people lose more, some less.

GLP-1 side effects

The most common side effects are stomach problems: feeling sick (nausea), diarrhea, throwing up and constipation. The Zepbound and Foundayo labels say they happened most while the dose was going up.

How many people felt sick (nausea) on GLP-1 drugs

% of adults with nausea in the weight-loss trials, drug vs placebo (fake medicine)

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

Show the numbers as a table
How many people felt sick (nausea) on GLP-1 drugs: % of adults with nausea in the weight-loss trials, drug vs placebo (fake medicine)
TrialDrugPlacebo
Wegovy shot (semaglutide 2.4 mg)
3 trials · 2,116 adults on the drug · up to 68 weeks		44%16%
Foundayo pill (orforglipron 17.2 mg)
2 trials · 1,049 adults on this dose · not a peptide		35%10%
Zepbound shot (tirzepatide 15 mg)
2 trials · 941 adults on this dose · up to 72 weeks		28%8%
Numbers are from each drug's FDA label. The Zepbound and Foundayo labels say stomach side effects happened most while the dose was going up. Sources: Wegovy FDA label, section 6.1, Table 3 (DailyMed); Foundayo FDA label, section 6.1, Table 1 (DailyMed); Zepbound FDA label, section 6.1, Table 1 (DailyMed).

Serious but less common: pancreatitis (bad belly pain that can go to your back), gallbladder problems, kidney problems from losing fluids, low blood sugar (mostly with insulin or other diabetes drugs), and allergic reactions. The labels also warn that the drug may make you more likely to breathe in food or liquid during surgery with anesthesia, so tell your surgeon you take it.

Some GLP-1 labels have a boxed warning: they caused thyroid tumors in rats and mice. No one knows if this happens in people.

Hair loss happened in about 3 to 5 in 100 people on Wegovy or Zepbound in trials. Read GLP-1 side effects: full list, GLP-1 hair loss, or check one drug in our side effects checker.

What happens if you stop a GLP-1?

For many people, weight comes back. In one trial, people stopped semaglutide after 68 weeks and were checked again 1 year later:

What happened after people stopped semaglutide

% of starting weight lost: at the end of treatment, and 1 year after stopping

Most of the lost weight came back within a year of stopping.

Show the numbers as a table
What happened after people stopped semaglutide: % of starting weight lost: at the end of treatment, and 1 year after stopping
TrialSemaglutide groupPlacebo group
Week 68: end of treatment
STEP 1 extension · 327 adults		−17.3%−2.0%
Week 120: 1 year after stopping
Same 327 adults · no drug, no diet program		−5.6%−0.1%
People in the semaglutide group regained about 11.6 of the 17.3 percentage points they had lost. Diet and exercise coaching also stopped at week 68. Blood pressure and sugar gains mostly went back toward the start, too. Sources: Wilding et al., Diabetes Obes Metab 2022 (STEP 1 extension) (PMID 35441470).

Do not stop or change your dose on your own. Talk with your doctor about a plan.

How much do GLP-1 drugs cost?

  • Insurance may pay if your plan lists the drug. Many plans have rules, like prior approval.
  • Medicare has a GLP-1 Bridge from July 1, 2026 to December 31, 2027: $50 a month for Wegovy, Foundayo or the Zepbound KwikPen, if you qualify.
  • Makers post cash prices. On October 23, 2026, Zepbound vials were $299 to $449 a month from Lilly, and the Wegovy pill and Foundayo started at $149 a month.

Check your path with Will insurance cover my GLP-1? and read Does insurance cover peptides?

Compounded GLP-1 vs FDA approved, and recalls

A compounded drug is mixed by a pharmacy. Compounded semaglutide and tirzepatide are not FDA approved. The FDA does not check them for safety, strength or quality before they are sold. That does not by itself make them illegal: pharmacies may compound only under certain rules.

  • As of May 31, 2026, the FDA had 990 reports of bad reactions with compounded semaglutide and more than 730 with compounded tirzepatide. The FDA says the real number is likely higher.
  • The FDA warns about dosing mistakes with multi-dose vials, fake pharmacy labels, and "salt forms" of semaglutide.
  • Retatrutide and cagrilintide cannot be used in compounding under federal law.
  • "Research use only" GLP-1 vials are not medicine. The FDA has warned sellers of these.

Our recall checker lists 25 compounded semaglutide or tirzepatide products from 5 pharmacies in FDA recall records (checked October 21, 2026). Check your lot number.

More: Is compounded semaglutide safe? and Compounded tirzepatide vs Zepbound.

Who should not take a GLP-1?

  • People who have had, or have family who had, a thyroid cancer called medullary thyroid cancer (MTC).
  • People with MEN 2, a rare gene problem that causes tumors.
  • People who had a serious allergic reaction to the drug.
  • Pregnant women. MedlinePlus says GLP-1 drugs are not recommended in pregnancy. Tell your doctor if you plan to get pregnant.
  • Tell your doctor if you have had pancreatitis, gallbladder, kidney or eye problems from diabetes.

Print our doctor questions sheet before your visit.

Read more about GLP-1

Start here

Side effects and safety

Compounded GLP-1 and recalls

Cost, pills and new drugs

GLP-1 FAQ

What does GLP-1 stand for?

Glucagon-like peptide-1. "Glucagon-like" means it looks a bit like glucagon, another hormone. "Peptide" means it is a short chain of amino acids.

Is Ozempic the same as Wegovy?

They have the same drug inside: semaglutide. Ozempic is approved for type 2 diabetes. Wegovy is approved for weight loss and other uses, at its own doses. Your doctor picks which one fits.

Can I buy GLP-1 over the counter?

No. Every FDA-approved GLP-1 drug needs a prescription. Pills or drops sold as "GLP-1 boosters" without a prescription are not GLP-1 drugs.

What is GLP-3?

It is a nickname people use online for retatrutide. It is not an official name, and retatrutide is not FDA approved.

Is BPC-157 a GLP-1?

No. BPC-157 does not work like GLP-1 drugs, is not FDA approved, and has very few studies in people.

Do I have to take a GLP-1 forever?

Many people do, because weight often comes back after stopping. Talk with your doctor before you stop or change your dose.

We never share doses or tell you where to buy. Always ask your doctor.

Sources

Not medical advice. Medical disclaimer.