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What is Tirzepatide?

Tirzepatide is a modified peptide, built on the sequence of the gut hormone GIP, that activates the receptors for two gut hormones, GIP and GLP-1, and has a half-life of about 5 days.8812 It is the active ingredient in two prescription medicines: Mounjaro, approved in 2022 for type 2 diabetes, and Zepbound, approved in 2023 for chronic weight management.345

This page summarizes published sources for information only. It is not medical advice and does not tell anyone to use a product. Questions about your own health belong with a licensed clinician. For questions about an order or a product, contact us.

Key facts

ClassDual GIP receptor and GLP-1 receptor agonist; MedlinePlus groups it with the incretin mimetics67
Also known asLY3298176 (research code); Mounjaro and Zepbound (brand names); TRZ GLP2 (the supplier's and this store's name for its research vial)891012
Approved forms (not sold here)Ready-to-use prescription solution in single-dose pens, single-dose vials, multi-dose vials and KwikPens119
Form sold hereResearch-labeled vial of freeze-dried tirzepatide, 5 mg, 20 mg, 30 mg12
Regulatory statusFDA-approved as Mounjaro (May 13, 2022) and Zepbound (November 8, 2023); research-labeled products have no approved FDA application31314
Half-lifeAbout 5 days; 5 to 6 days in people with overweight or obesity215
WADA statusNot on the Prohibited List: in 2026 WADA said GLP-1 receptor agonists, including tirzepatide, keep their status for 2027, as evidence does not yet show they meet its criteria for listing93

What sources report

Tirzepatide was developed by Eli Lilly under the research code LY3298176.89 It is a 39-amino-acid peptide built on the sequence of GIP, with a C20 fatty diacid that binds albumin.16881 That binding stretches its half-life to about 5 days, long enough for once-weekly dosing.12 A 2018 paper described its discovery and first clinical tests.16

How it works

  • Two receptors: it activates the receptors for GIP and GLP-1, hormones released by the intestine.117
  • Insulin and glucagon: it increases insulin release and lowers glucagon, both only when glucose is raised.18
  • Stomach emptying: it slows stomach emptying, most strongly after the first dose, and the effect fades over time.19
  • Appetite: it lowers calorie intake, likely by acting on appetite.20 GIP and GLP-1 receptors sit in brain areas that control appetite, and animal studies show tirzepatide reaches and activates neurons there.21
  • Balance between receptors (cell studies): a 2020 laboratory analysis estimated that, at clinically effective doses, it engages the GIP receptor more than the GLP-1 receptor, which the authors called an imbalanced mechanism.22

In the body

  • Absorption: about 80% of an injected dose reaches the blood, with similar exposure from the abdomen, thigh or upper arm.23
  • Steady state: blood levels level off after 4 weeks of once-weekly doses.24
  • Antibodies: 51% of people in the diabetes trials and 64.5% in the main weight-reduction trials formed antibodies to tirzepatide.2526 No clinically significant effect on drug levels or effectiveness was found, but adults with antibodies had more allergic reactions (4.1% vs 3.0%) and injection site reactions (4.6% vs 0.7%).27

What the trials found

Phase 3 trials enrolled from a few hundred to 13,299 adults each.2829 In type 2 diabetes, HbA1c fell about 1.9 to 2.3 percentage points over 40 weeks.3031 In adults with obesity or overweight who did not have diabetes, average weight fell 15.0% to 20.9% at 72 weeks, versus 3.1% on placebo.3233 Sleep apnea severity fell in two 52-week trials.3435 In a withdrawal trial, stopping treatment led to substantial weight regain.3637 Trials in heart failure with preserved ejection fraction and in fatty liver disease (MASH) also reported results, but neither is an approved use.3839440

Full summary with evidence levels: Tirzepatide benefits and uses. By goal: Tirzepatide and weight loss and Tirzepatide and blood sugar.

How it compares

  • Semaglutide: semaglutide is a selective GLP-1 receptor agonist.41 In head-to-head trials, tirzepatide lowered HbA1c more in type 2 diabetes (1,879 adults, 40 weeks).4231 It also lowered weight more in obesity: 20.2% versus 13.7% over 72 weeks in 751 adults.4344 See the semaglutide profile.
  • Retatrutide: retatrutide acts on three receptors, GIP, GLP-1 and glucagon, one more than tirzepatide.451 We found no head-to-head trial of the two. See the retatrutide profile.
  • Dulaglutide: in a heart outcomes trial of 13,299 adults with type 2 diabetes, major cardiovascular events occurred in 12.2% on tirzepatide and 13.1% on dulaglutide.46 Tirzepatide was noninferior, but not shown to be superior.4647

Each brand's label has its own page: Mounjaro and Zepbound.

Side effects

Stomach and bowel effects are the most common: in the weight-reduction trials, 56% of people on tirzepatide had them versus 30% on placebo, and nausea alone affected 25% to 29%.4849 In SURMOUNT-1, most were mild to moderate and occurred mainly while the dose was being raised.50 The labels carry a boxed warning about thyroid C-cell tumors seen in rats.51 They also list serious risks such as pancreatitis, gallbladder disease and kidney injury after dehydration.525354 Full list: Tirzepatide side effects.

Dosage information

Label dosing exists only for Mounjaro and Zepbound, and the prescriber sets each dose.910 Both labels start at 2.5 mg under the skin once weekly.5556 Any increase comes in 2.5 mg steps after at least 4 weeks on the current dose, up to 15 mg weekly in adults; the Mounjaro maximum for children is 10 mg.55575859 Zepbound uses 2.5 mg only to start; its maintenance doses are 5, 10 or 15 mg for weight and 10 or 15 mg for sleep apnea.5660 No dose is established for research-labeled vials.14 Full detail: Tirzepatide dosage.

Reconstitution and storage

The approved medicines need no mixing: they come as a clear, colorless to slightly yellow solution in pens and vials.11 The label says to store them in a refrigerator at 2°C to 8°C.61 Single-dose pens and vials may be kept unrefrigerated, at up to 30°C, for a total of 21 days.62 D2C Peptides sells tirzepatide only as a research-labeled vial of freeze-dried peptide, which has no FDA-reviewed mixing or storage directions.1214 Lab steps, supplies and concentration math: How to reconstitute Tirzepatide. Vial sizes and specifications: Buy Tirzepatide.

Regulatory status

  • Mounjaro: FDA first approved tirzepatide as Mounjaro on May 13, 2022, as a new molecular entity.3 Mounjaro is approved to improve blood sugar control in adults and children 10 and older with type 2 diabetes.4 It is also approved to lower the risk of major cardiovascular events in high-risk adults with type 2 diabetes.63 The pediatric use was added in December 2025 and the heart indication in August 2026.64
  • Zepbound: approved on November 8, 2023, for chronic weight management, and on December 20, 2024, for moderate to severe obstructive sleep apnea in adults with obesity.565 Both brands are prescription drugs.910
  • European Union: Mounjaro was authorised on 15 September 2022.66 It is used for type 2 diabetes in adults and in children aged 10 and older, and for weight management in adults, by prescription only.676869
  • Shortage: tirzepatide injection was in shortage from 2022 until FDA declared it resolved in October 2024, a decision FDA confirmed in December 2024.707172
  • Compounding: compounded tirzepatide is not FDA-approved.73 Since the shortage ended, pharmacies may not regularly compound essentially copies of the approved drug.74 FDA has said it does not intend to act when a compounder fills four or fewer such prescriptions in a calendar month.75 On April 30, 2026, FDA proposed excluding tirzepatide from the 503B bulks list used by outsourcing facilities, with comments due by June 29, 2026.7677
  • Research-labeled products: FDA has warned companies that sold tirzepatide falsely labeled "for research purposes" or "not for human consumption" to consumers with dosing instructions.7879 It urges consumers to avoid these products, which it calls of unknown quality.79 Warning letters dated December 2024, March 2026 and August 2026 called research-labeled tirzepatide an unapproved new drug.808182

More on Tirzepatide

  • Tirzepatide side effects

    Side effects of Tirzepatide as reported in labels, trials and published studies, with links to the full profile. Reviewed by a qualified reviewer.

  • Tirzepatide dosage

    Published dosing information for Tirzepatide from labels and studies, with its source, and why it is not advice for you.

  • Tirzepatide benefits and uses

    What published sources report about Tirzepatide and its uses, with the evidence level of each finding. No promises.

  • How to reconstitute Tirzepatide

    How Tirzepatide is reconstituted, the supplies used, and the calculator, step by step. Sourced and reviewed.

Tirzepatide in the store

Tirzepatide for sale: strengths, stock and shipping are on the product page.

For research use only. Not for human or veterinary use. Read the research use policy.

Related reading

Related profiles

Comparisons

Tirzepatide and research goals

Frequently asked questions

Is there still a shortage of tirzepatide?

No. Tirzepatide injection had been in shortage since 2022.70 FDA declared the shortage resolved on October 2, 2024, re-evaluated that decision, and confirmed it on December 19, 2024.7172 As of FDA's April 1, 2026 update, tirzepatide is not on the drug shortage list.83 FDA's temporary leniency for compounders, which depended on the shortage listing, ended in March 2025.8485

Is tirzepatide the same as Ozempic?

No. Ozempic's active ingredient is semaglutide, which the authors of a head-to-head trial describe as a selective GLP-1 receptor agonist.8641 Tirzepatide is a different molecule that activates both the GIP and GLP-1 receptors.1 In that 40-week trial of 1,879 adults with type 2 diabetes, every tirzepatide dose lowered HbA1c more than semaglutide 1 mg.4231 More detail: Ozempic vs Tirzepatide.

Is tirzepatide peptide the same as Mounjaro?

Mounjaro is Eli Lilly's FDA-approved tirzepatide, a ready-to-use solution listed as a prescription drug.911 Tirzepatide sold online as a research peptide is a different product. FDA has called research-labeled tirzepatide an unapproved new drug with no approved application, and describes such products as of unknown quality.811479 More detail: Mounjaro vs Tirzepatide.

What class of medication does tirzepatide belong to?

FDA's pharmacologic class terms describe tirzepatide as both a GIP receptor agonist and a GLP-1 receptor agonist.6 MedlinePlus places it among the incretin mimetics, medicines that help the pancreas release the right amount of insulin when blood sugar is high.7 So it is a GLP-1 medicine, but not only one: a 2020 lab study estimated that it engages the GIP receptor more than the GLP-1 receptor.22

Is tirzepatide legal?

Yes, as a prescription medicine. In the US it is marketed as Mounjaro and Zepbound, which FDA lists as prescription drugs.910 In the EU, Mounjaro can only be obtained with a prescription.69 FDA has sent warning letters to sellers of research-use-only tirzepatide, saying those labels did not stop the products from being unapproved new drugs when the sellers' websites showed they were meant for human use.8782

Is tirzepatide a peptide, and what is its structure?

Yes. Tirzepatide is a linear peptide of 39 amino acids based on the GIP hormone sequence.1688 It has aminoisobutyric acid at positions 2 and 13, an amidated C-terminal end, and a C20 fatty diacid attached through a linker to the lysine at position 20.88 Its formula is C225H348N48O68 and its molecular weight is 4813.53 Da.89

Do I need to see a doctor to get tirzepatide?

For the approved medicines, yes. FDA lists Mounjaro and Zepbound as prescription drugs.910 FDA advises patients to get a prescription from their doctor and fill it at a state-licensed pharmacy, and warns that illegally marketed GLP-1 drugs may be counterfeit or contain the wrong ingredients.9091 FDA's 2023 approval of Zepbound covered adults with a BMI of 30 or more, or 27 or more with at least one weight-related condition.92

Written by D2C Peptides Editorial Team.

Pending qualified review.

Updated .

Sources

  1. MOUNJARO Prescribing Information, revised 08/2026: Mechanism of action. U.S. Food and Drug Administration (label for Eli Lilly and Company), 2026.
  2. Same source as 1: Elimination.
  3. Drugs@FDA: NDA 215866 (MOUNJARO), original approval. U.S. Food and Drug Administration, 2026.
  4. Same source as 1: MOUNJARO (tirzepatide) US Prescribing Information, revised 08/2026: Indications (type 2 diabetes).
  5. FDA Approves New Medication for Chronic Weight Management (news release). U.S. Food and Drug Administration, 2023.
  6. Tirzepatide, CID 156588324: Names and Identifiers (FDA Pharm Classes description). PubChem, NIH National Library of Medicine, 2026.
  7. Tirzepatide Injection (drug information, revised 02/15/2026): drug class. MedlinePlus, NIH National Library of Medicine, 2026.
  8. Tirzepatide is an imbalanced and biased dual GIP and GLP-1 receptor agonist (Willard et al.), PubMed record PMID 32730231. JCI Insight (via NLM PubMed E-utilities), 2020.
  9. Same source as 3: sponsor and marketing status.
  10. Drugs@FDA: NDA 217806 (ZEPBOUND), marketing status. U.S. Food and Drug Administration, 2026.
  11. Same source as 1: Dosage forms.
  12. Supplier product specification.
  13. Same source as 10: original approval.
  14. FDA Warning Letter: Gram Peptides, March 31, 2026 (no approved application). U.S. Food and Drug Administration, CDER, 2026.
  15. ZEPBOUND Prescribing Information, revised 08/2026: Elimination half-life. U.S. Food and Drug Administration (label for Eli Lilly and Company), 2026.
  16. LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept (Coskun et al.). Molecular Metabolism, 2018.
  17. Same source as 5: mechanism.
  18. Same source as 1: Insulin and glucagon.
  19. Same source as 1: Gastric emptying.
  20. Same source as 15: Pharmacodynamics (body composition, calorie intake).
  21. Same source as 15: Mechanism of action (appetite).
  22. Same source as 8: Willard et al. 2020, receptor occupancy finding (PMID 32730231).
  23. Same source as 1: Absorption.
  24. Same source as 1: Steady state.
  25. Same source as 1: Immunogenicity (incidence).
  26. Same source as 15: Immunogenicity.
  27. Same source as 1: Immunogenicity (effects).
  28. Same source as 15: Obstructive sleep apnea studies.
  29. Same source as 1: SURPASS-CVOT design.
  30. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in patients with type 2 diabetes (SURPASS-1), PMID 34186022. The Lancet (via NLM PubMed E-utilities), 2021.
  31. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2), PMID 34170647. New England Journal of Medicine (via NLM PubMed E-utilities), 2021.
  32. SURMOUNT-1 abstract: weight change at 5 mg and 10 mg (PMID 35658024). New England Journal of Medicine (via NLM PubMed E-utilities), 2022.
  33. Same source as 32: weight change at 15 mg and placebo (PMID 35658024).
  34. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA), PMID 38912654: trial 1. New England Journal of Medicine (via NLM PubMed E-utilities), 2024.
  35. Same source as 34: SURMOUNT-OSA abstract: trial 2 (PMID 38912654).
  36. SURMOUNT-4 abstract: randomized withdrawal results (PMID 38078870). JAMA (via NLM PubMed E-utilities), 2024.
  37. Same source as 36: conclusions (PMID 38078870).
  38. SUMMIT abstract: primary outcome (PMID 39555826). New England Journal of Medicine (via NLM PubMed E-utilities), 2025.
  39. Tirzepatide for Metabolic Dysfunction-Associated Steatohepatitis with Liver Fibrosis (SYNERGY-NASH), PMID 38856224: MASH resolution. New England Journal of Medicine (via NLM PubMed E-utilities), 2024.
  40. Same source as 15: ZEPBOUND (tirzepatide) US Prescribing Information, revised 08/2026: Indications (weight).
  41. Same source as 31: SURPASS-2 abstract: background (PMID 34170647).
  42. Same source as 1: SURPASS-2 design.
  43. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5), PMID 40353578: weight. New England Journal of Medicine (via NLM PubMed E-utilities), 2025.
  44. Same source as 43: SURMOUNT-5 abstract: methods (PMID 40353578).
  45. Triple-Hormone-Receptor Agonist Retatrutide for Obesity: A Phase 2 Trial, PMID 37366315: background. New England Journal of Medicine (via NLM PubMed E-utilities), 2023.
  46. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes (SURPASS-CVOT), PMID 41406444. New England Journal of Medicine (via NLM PubMed E-utilities), 2025.
  47. Same source as 1: SURPASS-CVOT results.
  48. Same source as 15: Gastrointestinal adverse reactions.
  49. Same source as 15: Table 1, weight-reduction trials (placebo, 5 mg, 10 mg, 15 mg; %).
  50. Same source as 32: cardiometabolic measures and adverse events (PMID 35658024).
  51. Same source as 1: Boxed warning.
  52. Same source as 1: Acute pancreatitis.
  53. Same source as 1: Acute gallbladder disease.
  54. Same source as 1: Acute kidney injury.
  55. Same source as 1: Recommended dosage.
  56. Same source as 15: Starting dosage.
  57. Same source as 15: Dose escalation.
  58. Same source as 1: Maximum dosage.
  59. Same source as 15: Maximum dosage.
  60. Same source as 15: Maintenance dosage.
  61. Same source as 15: Storage (refrigeration).
  62. Same source as 15: Storage (room temperature).
  63. Same source as 1: Indications (cardiovascular risk).
  64. Same source as 1: Recent Major Changes.
  65. FDA Approves First Medication for Obstructive Sleep Apnea (news release). U.S. Food and Drug Administration, 2024.
  66. Mounjaro: EPAR (authorisation). European Medicines Agency, 2026.
  67. Same source as 66: EPAR overview (type 2 diabetes).
  68. Same source as 66: EPAR overview (weight).
  69. Same source as 66: EPAR (how it is used).
  70. FDA clarifies policies for compounders: shortage history. U.S. Food and Drug Administration, 2026.
  71. Same source as 70: FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize (October 2, 2024 entry).
  72. Same source as 70: FDA clarifies policies for compounders (December 19, 2024 entry).
  73. Same source as 70: approval status of compounded drugs.
  74. Same source as 70: section 503A conditions.
  75. Same source as 70: four-prescription policy.
  76. FDA Proposes to Exclude Semaglutide, Tirzepatide, and Liraglutide on 503B Bulks List (news release). U.S. Food and Drug Administration, 2026.
  77. Same source as 76: comment period.
  78. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss: research-labeled products. U.S. Food and Drug Administration, 2026.
  79. Same source as 78: consumer warning.
  80. FDA Warning Letter: Summit Research Peptides (MARCS-CMS 695607), December 10, 2024. U.S. Food and Drug Administration, CDER, 2024.
  81. Same source as 14: Gram Peptides (MARCS-CMS 721806), March 31, 2026.
  82. FDA Warning Letter: Royal Peptides LLC (MARCS-CMS 734884), August 24, 2026. U.S. Food and Drug Administration, CDER, 2026.
  83. Same source as 70: FDA clarifies policies for compounders (April 1, 2026 entry).
  84. Same source as 70: FDA clarifies policies for compounders (March 10, 2025 entry, 503A).
  85. Same source as 70: FDA clarifies policies for compounders (March 10, 2025 entry, 503B).
  86. Drugs@FDA: NDA 209637 (OZEMPIC), active ingredient. U.S. Food and Drug Administration, 2026.
  87. Same source as 14: 2026 (research use only labeling).
  88. Same source as 1: Description (structure).
  89. Same source as 1: Description (formula).
  90. Same source as 78: recommendations.
  91. Same source as 78: illegally marketed versions.
  92. Same source as 5: eligible adults.
  93. WADA publishes 2027 Prohibited List. World Anti-Doping Agency (WADA), 2026.