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GLP-1 Medicines: Semaglutide, Tirzepatide and Liraglutide

A plain-language class overview of prescription GLP-1 medicines (semaglutide, tirzepatide, liraglutide, dulaglutide): US label uses, trial results, boxed warning and safety.

Content last updated . This page has not been medically reviewed.

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What this page covers

GLP-1 medicines are prescription peptide drugs that copy a gut hormone called glucagon-like peptide-1. This page is an overview of the class. It sorts out which molecule is sold under which brand, what each US label says it is approved for, what the main trials found, and what the labels warn about. It gives no amounts, no sourcing and no advice to start, stop, switch or combine medicines. Questions about your own treatment belong with your prescriber.

How these medicines work

Each of these drugs is a lab-made version of, or close relative of, a natural gut hormone. The semaglutide label calls it a GLP-1 analogue with 94% sequence similarity to human GLP-1 that activates the GLP-1 receptor, a natural regulator of appetite and calorie intake. [1] Liraglutide is described as 97% similar to a natural form of human GLP-1. [2] Dulaglutide is 90% similar. [3] Tirzepatide is different: it activates both the GIP receptor and the GLP-1 receptor, and a fatty-acid side chain lets it bind albumin, which lengthens its half-life. [4] The NHS describes the effect in plain terms as reduced appetite and slower digestion. [5]

Molecule, brand and use are not the same thing

One molecule can be sold under several brands with different approved uses. The table shows what the US labels said on the dates read.
Active ingredientUS brand (form)Uses stated in the US label
SemaglutideOzempic (injection)Type 2 diabetes blood sugar control; lowering heart-event risk in type 2 diabetes with established heart disease; lowering kidney and heart risks in type 2 diabetes with chronic kidney disease [6]
SemaglutideRybelsus and Ozempic tablets (oral)Type 2 diabetes blood sugar control; lowering heart-event risk in high-risk adults with type 2 diabetes [7]
SemaglutideWegovy (injection and tablets)Weight reduction and maintenance in obesity or overweight with a related condition (injection from age 12 for obesity); lowering heart-event risk with established heart disease; liver scarring (MASH) stages F2 to F3 in adults, under accelerated approval [1]
TirzepatideMounjaroType 2 diabetes (adults and children 10 and older); lowering heart-event risk in high-risk adults with type 2 diabetes [8]
TirzepatideZepboundWeight reduction and maintenance in adults with obesity or overweight with a related condition; moderate to severe obstructive sleep apnea in adults with obesity [4]
LiraglutideVictozaType 2 diabetes (adults and children 10 and older); lowering heart-event risk in type 2 diabetes with established heart disease [2]
LiraglutideSaxendaWeight reduction and maintenance in adults and in children 12 and older (over 60 kg) with obesity, or adults with overweight plus a related condition [9]
DulaglutideTrulicityType 2 diabetes (adults and children 10 and older); lowering heart-event risk in adults with type 2 diabetes [3]

The labels also say that using one of these products together with another product that contains the same molecule, or with any other GLP-1 receptor agonist, is not recommended. [1][9]

The same molecule can be labeled differently elsewhere

The EMA lists tirzepatide as Mounjaro for both type 2 diabetes (adults, adolescents and children aged 10 and over) and weight management in adults. [10] In the US the two uses carry separate brand names. The EMA lists Wegovy for weight management in adults and adolescents from age 12 as pens, and as tablets for adults only, while its Ozempic page covers type 2 diabetes in adults. [11][12] In the UK the NHS names Wegovy for obesity and Ozempic and Rybelsus for type 2 diabetes, Mounjaro for tirzepatide, and Saxenda for obesity with Diavic and Zegluxen for diabetes in the case of liraglutide. [5][13][14]

What the main trials showed

These are published results for the products named, with the amounts and settings the trials used. They do not predict any one person's result.
5 findings · 5 limited or unclearThe colour follows the evidence label on each card.

  1. STEP 1 (semaglutide, weight)

    Average weight change -14.9% vs -2.4% on placebo; 4.5% vs 0.8% stopped for stomach and gut events [15]

    Who and how long: 1,961 adults with overweight or obesity, no diabetes; 68 weeks plus lifestyle supportFunder: Novo Nordisk

  2. SURMOUNT-1 (tirzepatide, weight)

    -15.0% to -20.9% across three study strengths vs -3.1% on placebo [16]

    Who and how long: 2,539 adults, no diabetes; 72 weeksFunder: Eli Lilly

  3. SCALE (liraglutide, weight)

    Average loss 8.4 kg vs 2.8 kg; serious events 6.2% vs 5.0% [17]

    Who and how long: 3,731 adults, no type 2 diabetes; 56 weeksFunder: Novo Nordisk

  4. SELECT (semaglutide, heart outcomes)

    Major heart event 6.5% vs 8.0% (hazard ratio 0.80); permanent stopping for adverse events 16.6% vs 8.2% [18]

    Who and how long: 17,604 adults 45 or older with heart disease and overweight or obesity, no diabetes; mean follow-up about 40 monthsFunder: Novo Nordisk

  5. SURPASS-2 (tirzepatide vs semaglutide, type 2 diabetes)

    HbA1c fell more with tirzepatide at all three study strengths than with the semaglutide comparator [19]

    Who and how long: 1,879 adults; 40 weeks, open-labelFunder: Eli Lilly

Evidence label: established for short- to medium-term weight reduction and, for semaglutide in SELECT, fewer major heart events in the populations studied. The trials were run or paid for by the manufacturers, ran for months to a few years, and report averages. SURPASS-2 compared blood sugar and weight changes, which are measured outcomes, not a head-to-head comparison of long-term health results. The trials cannot say what happens after stopping or over many years.

Professional-care context

These are prescription medicines started and followed by a clinician. The labels describe checking for conditions that raise risk (for example thyroid cancer history, diabetic eye disease and kidney problems), and say routine calcitonin blood tests or thyroid ultrasound are of uncertain value for catching thyroid tumors early. [1] For goals, eligibility and follow-up, see weight-loss medications and medical care.

Questions this page does not settle

Compounded or unapproved semaglutide and tirzepatide products are not covered by the approvals above; see compounded and unapproved GLP-1 products. Long-term outcomes after stopping, and uses outside the labeled ones, are not established by the sources read here.

Related guides

Individual medicine guides: semaglutide, tirzepatide, liraglutide and dulaglutide. For comparisons and background see semaglutide vs tirzepatide, GLP-1 and GIP biology, metabolic and diabetes peptide medicines, what peptides are, weight safety and when to get help and medication interactions.

Frequently asked questions

Are GLP-1 drugs peptides?

Yes. They are prescription peptide medicines built on a natural gut hormone. [1][4]

Is Ozempic the same as Wegovy?

Both contain semaglutide, but they are different products with different US label uses: Ozempic is labeled for type 2 diabetes, and Wegovy for weight and related conditions. [6][1]

How much weight did people lose in the trials?

Averages were about 15% with semaglutide over 68 weeks, 15% to 21% with tirzepatide over 72 weeks, and about 8 kg with liraglutide over 56 weeks, compared with smaller changes on placebo. Individual results vary. [15][16][17]

What is the boxed warning about?

It concerns thyroid C-cell tumors seen in rodents; the labels say it is unknown whether humans are affected. [1]

Can I stop or change my medicine based on this page?

No. This is education only. Ask your prescriber before any change.

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

How to read the evidence labels

Labels used on this page: approved medicine means the regulator named has approved that product for the indication named. Established means large, well-run trials agree on a result. Label statements were read from the US FDA labels on DailyMed, the European Medicines Agency (EMA) pages and NHS pages on 2026-10-22. Other countries were not checked. Rules and labels change.

Safety information from the labels
  • Boxed warning (the FDA's strongest label warning). Semaglutide, tirzepatide, liraglutide and dulaglutide carry a warning about thyroid C-cell tumors. In rodents these drugs caused such tumors; the labels say it is unknown whether they do in humans. They are contraindicated with a personal or family history of medullary thyroid carcinoma or with multiple endocrine neoplasia type 2. [1][4][9][3]
  • Other contraindication. A prior serious allergic reaction to the drug or its ingredients. [1][2]
  • Warnings and precautions listed include acute pancreatitis, gallbladder disease, severe stomach and gut reactions, kidney injury from dehydration, hypersensitivity reactions, worsening of diabetic eye disease (in people with type 2 diabetes), and low blood sugar when combined with insulin or sulfonylureas. [1][8]
  • Anesthesia. Because these drugs delay stomach emptying, the label describes rare reports of food or fluid entering the lungs during anesthesia or deep sedation despite fasting, so tell the surgical team about the medicine. [4]
  • Common effects. In Wegovy weight trials in adults, nausea was reported by 44% on the drug vs 16% on placebo, diarrhea 30% vs 16%, vomiting 24% vs 6% and constipation 24% vs 11%. [1] The NHS lists nausea, vomiting, constipation, diarrhea and tiredness as common, with hair loss listed for semaglutide and tirzepatide. [5][13]
  • Other medicines. The Zepbound label says tirzepatide delays stomach emptying, which may change how oral medicines are absorbed, and it tells prescribers to advise people using oral hormonal contraceptives about switching to a non-oral method or adding a barrier method around starting and each dose increase. [4] Ask the prescriber about this.
  • Pregnancy and breastfeeding. The Zepbound label says weight loss offers no benefit in pregnancy and may cause fetal harm. [4] The NHS says there is not enough information to say these medicines are safe in pregnancy and that semaglutide is not used while breastfeeding. [5] Anyone pregnant or planning pregnancy should speak with a prescriber.
  • Fake products. The NHS warns that some websites sell fake weight-loss medicines and says to get these medicines from a registered pharmacy. [5]

Seek urgent medical help for severe, persistent stomach pain, swelling of the throat or tongue, or trouble breathing. [5]

References
  1. U.S. National Library of Medicine, DailyMed. Wegovy (semaglutide) injection and tablets, label effective 2026-06-18 (FDA prescribing information). Read 2026-10-22.
  2. U.S. National Library of Medicine, DailyMed. Victoza (liraglutide), label effective 2025-10-14 (FDA prescribing information). Read 2026-10-22.
  3. U.S. National Library of Medicine, DailyMed. Trulicity (dulaglutide), label effective 2026-06-16 (FDA prescribing information). Read 2026-10-22.
  4. U.S. National Library of Medicine, DailyMed. Zepbound (tirzepatide), label effective 2026-08-28 (FDA prescribing information). Read 2026-10-22.
  5. NHS. Semaglutide. Read 2026-10-22.
  6. U.S. National Library of Medicine, DailyMed. Ozempic (semaglutide) injection, label effective 2026-06-01 (FDA prescribing information). Read 2026-10-22.
  7. U.S. National Library of Medicine, DailyMed. Rybelsus and Ozempic (oral semaglutide) tablets, label effective 2026-01-30 (FDA prescribing information). Read 2026-10-22.
  8. U.S. National Library of Medicine, DailyMed. Mounjaro (tirzepatide), label effective 2026-08-27 (FDA prescribing information). Read 2026-10-22.
  9. U.S. National Library of Medicine, DailyMed. Saxenda (liraglutide), label effective 2026-02-25 (FDA prescribing information). Read 2026-10-22.
  10. European Medicines Agency. Mounjaro (tirzepatide): EPAR overview. Read 2026-10-22.
  11. European Medicines Agency. Wegovy (semaglutide): EPAR overview. Read 2026-10-22.
  12. European Medicines Agency. Ozempic (semaglutide): EPAR overview. Read 2026-10-22.
  13. NHS. Tirzepatide. Read 2026-10-22.
  14. NHS. Liraglutide. Read 2026-10-22.
  15. Wilding JPH et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med 2021. PubMed. Read 2026-10-22.
  16. Jastreboff AM et al. Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1). N Engl J Med 2022. PubMed. Read 2026-10-22.
  17. Pi-Sunyer X et al. A randomized, controlled trial of 3.0 mg of liraglutide in weight management (SCALE). N Engl J Med 2015. PubMed. Read 2026-10-22.
  18. Lincoff AM et al. Semaglutide and cardiovascular outcomes in obesity without diabetes (SELECT). N Engl J Med 2023. PubMed. Read 2026-10-22.
  19. Frias JP et al. Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2). N Engl J Med 2021. PubMed. Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.