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D2C Peptides

Brand-name medicine

What is Zepbound?

Zepbound is Eli Lilly's brand of tirzepatide, a once-weekly prescription injection that activates GIP and GLP-1 receptors.12 FDA approved it in November 2023 for chronic weight management in adults with obesity, or overweight with a weight-related condition.3 In December 2024 it was approved for moderate to severe obstructive sleep apnea in adults with obesity.4

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

Active ingredientTirzepatide5
ClassDual GIP receptor and GLP-1 receptor agonist2
Also known asZepbound single-dose pen, Zepbound vial, Zepbound KwikPen; studied under the code LY329817656
MakerEli Lilly and Company; marketed in the US by Lilly USA, LLC, of Indianapolis, Indiana17
FormsSingle-dose pen, single-dose vial, multi-dose vial and KwikPen, in six strengths from 2.5 mg to 15 mg per weekly dose5
Sold hereNo. Zepbound is a prescription medicine and is not sold here.1
Approved usesReducing excess body weight and keeping it off in adults with obesity, or overweight with a weight-related condition; moderate to severe obstructive sleep apnea in adults with obesity8
Regulatory statusFDA-approved, prescription only, NDA 217806, first approved November 8, 202313
Boxed warningRisk of thyroid C-cell tumors, seen in rats9

What sources report

Zepbound is the name Eli Lilly uses for tirzepatide when it is prescribed for weight reduction or obstructive sleep apnea (OSA).8 It is injected under the skin once a week, from a prefilled pen or a vial, as a ready-to-use solution.205 The same molecule is marketed as Mounjaro for type 2 diabetes.10 The compound itself, its chemistry and its wider research record are covered in What is Tirzepatide?.

How tirzepatide works

Tirzepatide switches on two hormone receptors, the GIP receptor and the GLP-1 receptor.2 Its targets include receptors in brain areas that regulate appetite.2 According to the label, it lowers calorie intake, probably by acting on appetite, and the weight lost is more fat mass than lean mass.2 It also slows stomach emptying, most strongly after the first dose.2

The molecule is a 39-amino-acid peptide built on the sequence of the GIP hormone.215 It carries aminoisobutyric acid at positions 2 and 13, and a C20 fatty diacid attached at lysine 20.5 That fatty chain binds albumin in the blood, which lengthens the half-life to about 5 days.222 The molecular weight is 4813.53 Da and the formula is C225H348N48O68.5

What the trials found

In Study 1 of the label, 2,539 adults with obesity, or overweight plus a weight-related condition, and no type 2 diabetes were treated for 72 weeks.23 Mean weight loss by dose was 15.0% (5 mg), 19.5% (10 mg) and 20.9% (15 mg), compared with 3.1% for placebo.23 Two 52-week trials, Studies 5 and 6, enrolled 469 adults with obesity and moderate to severe OSA.13 Their apnea-hypopnea index fell by 25.3 and 29.3 events per hour, against 5.3 and 5.5 on placebo.13 In Study 4, people switched to placebo after 36 weeks on Zepbound saw their weight rise 14.0% over the next 52 weeks, while those who stayed on it lost a further 5.5%.24 Full summary with evidence levels: Zepbound benefits and uses.

Side effects

Digestive effects lead the list: in the 72-week weight trials, nausea affected 25% to 29% of patients and diarrhea 19% to 23%, against 8% each on placebo.25 The boxed warning covers thyroid C-cell tumors seen in rats.9 Zepbound must not be used by people with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2).26 Other label warnings include pancreatitis, gallbladder disease, kidney injury from dehydration and serious allergic reactions.27 Full list: Zepbound side effects.

Dosage information

Under the label, treatment starts at 2.5 mg once a week for 4 weeks, then rises to 5 mg; the 2.5 mg dose is only for starting and is not a maintenance dose.14 Any later increase is 2.5 mg and comes no sooner than 4 weeks after the last one.14 For weight reduction the maintenance options are 5, 10 or 15 mg a week; for sleep apnea they are 10 or 15 mg, and 15 mg a week is the maximum.14 The prescriber sets the dose, weighing response and tolerability.14 Full schedule: Zepbound dosage.

How it is used

Zepbound is injected under the skin once a week, at any time of day, with or without meals.20 It is meant to go with a reduced-calorie diet and more physical activity.20 Before the first dose, a healthcare provider should train the patient or caregiver on the exact presentation prescribed, and train them again if it changes.20

Pens and vials

The label lists four presentations, all ready-to-use solutions.5

Presentation What it holds How each dose is given
Single-dose pen One weekly dose of 2.5 mg to 15 mg in 0.5 mL; 4 pens per carton5 One injection per pen, started with a button28
Single-dose vial One dose of 2.5 mg to 15 mg in 0.5 mL5 Drawn up with a new syringe and needle19
Multi-dose vial 2.4 mL holding four weekly doses of 0.6 mL5 A new syringe and needle for each dose19
KwikPen 2.4 mL holding four fixed weekly doses5 A new pen needle and a priming step before each dose29

Giving the injection

The Instructions for Use describe these steps for prescribed patients:

  • Site. The stomach area or thigh, or the back of the upper arm when someone else gives the injection, but never a muscle or vein.207
  • Rotation. A different spot every week, though the same body area can be reused.207 Skin that is bruised, scarred, thickened, tender, scaly or hard is avoided, and rotating lowers the risk of lipodystrophy and localized cutaneous amyloidosis.19
  • Liquid check. It should be clear and colorless to slightly yellow, and it is not used if it has particles or looks discolored.20
  • Single-dose pen. The gray base cap comes off, the clear base sits flat on the skin, and the lock ring is turned.28 The purple button is then pressed and held for up to 10 seconds.28 The first click means the injection has started; the second means it is complete.28
  • Single-dose vial. A new syringe and needle draw up 0.5 mL, and the needle stays in the skin for at least 5 seconds.19 The opened vial is thrown away after one use, even if liquid remains.19
  • Multi-dose vial. Each weekly dose is 0.6 mL, drawn up with a new syringe and needle, and one vial gives 4 doses.2019
  • KwikPen. A new pen needle goes on, and the pen is primed before every dose.29 The dose knob is turned until it stops, then pushed in and held for a slow count of 5.28 After 4 doses the pen is thrown away, even if medicine remains, and the medicine is never moved into a syringe.29
  • No sharing. A KwikPen is never shared, even with a new needle, because of the risk of passing on blood-borne infections.2729
  • Disposal. Used needles and syringes go straight into an FDA-cleared sharps disposal container.2919

General technique for prescribed under-the-skin injections is covered in How subcutaneous injections are given.

Storage

  • Pens and vials are kept in the refrigerator at 2°C to 8°C (36°F to 46°F), in the original carton to protect them from light, and away from heat.307 Zepbound is never frozen, and product that has frozen is not used.30
  • A single-dose pen or single-dose vial can stay unrefrigerated, at up to 30°C (86°F), for a total of 21 days, and is then thrown away.307 In April 2026, FDA approved a stability study showing that single-dose tirzepatide presentations keep acceptable quality when moved in and out of the refrigerator during that 21-day period.31
  • Unopened multi-dose vials and KwikPens keep in the refrigerator until the expiration date, or for 30 days at room temperature up to 30°C.30
  • Once opened, multi-dose vials and KwikPens can stay in the refrigerator or at up to 30°C.30 They are thrown away 30 days after first use, after 30 days in total at room temperature, or after 4 weekly doses, even if medicine is left.307
  • A KwikPen is stored with its cap on and no needle attached, which prevents leaks, blocked needles and air in the pen.29
  • Zepbound, needles and syringes are kept out of the reach of children.719

Regulatory status

Zepbound is approved under NDA 217806, held by Eli Lilly, and FDA lists it as a prescription drug.1 Its active ingredient was first approved in the US in 2022, as Mounjaro.38

  • November 8, 2023. Approved for chronic weight management in adults with a BMI of 30 or more, or 27 or more with a weight-related condition.3 Use is alongside a reduced-calorie diet and more activity.3
  • December 20, 2024. Approved for moderate to severe OSA in adults with obesity.4
  • January 20, 2026. FDA approved the KwikPen, a single-patient-use pen holding 4 fixed weekly doses, in six strengths from 2.5 mg to 15 mg.325
  • February 25, 2026. A safety labeling change removed the suicidal behavior and ideation warning.33 It also added intestinal obstruction and severe constipation, including fecal impaction, to the postmarketing reports.33
  • August 26, 2026. A label update tied to SURPASS-CVOT, a trial of tirzepatide against dulaglutide in adults with type 2 diabetes and established cardiovascular disease, revised the diabetic retinopathy warning.34 Zepbound's two approved uses stayed the same.348

In the European Union, tirzepatide is authorized under the Mounjaro name, first on September 15, 2022, and its uses there include weight management in adults.35

Compounded and research-labeled tirzepatide

FDA says compounded drugs are not FDA approved and are not reviewed by FDA for safety, effectiveness or quality before they are marketed.17 It declared the tirzepatide injection shortage resolved on December 19, 2024.36 As of May 31, 2026, FDA had received more than 730 reports of adverse events associated with compounded tirzepatide.37 FDA has also warned companies that illegally sold unapproved tirzepatide, falsely labeled 'for research purposes' or 'not for human consumption', to consumers with dosing instructions.18 It describes these products as of unknown quality.18 None of them is Zepbound, which is the FDA-approved, prescription-only brand from Eli Lilly.1

More on Zepbound

  • Zepbound side effects

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

  • Zepbound dosage

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

  • Zepbound benefits and uses

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

Related reading

Related profiles

Frequently asked questions

Is Zepbound the same as Mounjaro?

They contain the same medicine: both are tirzepatide from Eli Lilly, made in the same six dose strengths.510 Mounjaro is approved for blood sugar control in type 2 diabetes, in adults and children 10 and older.10 It is also approved to lower the risk of major cardiovascular events in high-risk adults with type 2 diabetes.11 Zepbound is approved for weight reduction and obstructive sleep apnea, and its label advises against combining it with other tirzepatide products or any GLP-1 receptor agonist.8

Do I need a prescription for Zepbound?

Yes. Drugs@FDA lists Zepbound's marketing status as prescription, under Eli Lilly's application NDA 217806.1 Lilly says the prescription can be filled through LillyDirect or at a retail pharmacy.12 The weight use covers adults with a BMI of 30 or more, or 27 or more with at least one weight-related condition.3 The sleep apnea use covers adults with obesity and moderate to severe obstructive sleep apnea.8

Which company is the manufacturer of Zepbound?

Eli Lilly and Company makes Zepbound and holds its FDA application, NDA 217806.1 In the US it is marketed by Lilly USA, LLC, of Indianapolis, Indiana.7 Lilly also makes Mounjaro, which contains the same active ingredient and was approved first, in 2022, for type 2 diabetes.38

Is Zepbound used for sleep apnea?

Yes. On December 20, 2024, FDA approved Zepbound to treat moderate to severe obstructive sleep apnea in adults with obesity, together with a reduced-calorie diet and more physical activity.4 FDA called it the first drug treatment option for certain patients with the condition.4 The supporting trials ran for 52 weeks in 469 adults, and the label's maintenance dose for this use is 10 mg or 15 mg once weekly.1314

What diseases does Zepbound treat?

Zepbound has two FDA-approved uses.8 The first is reducing excess body weight and keeping it off long term in adults with obesity, or adults with overweight and at least one weight-related condition.8 The second is moderate to severe obstructive sleep apnea in adults with obesity.8 It is not approved for blood sugar control in type 2 diabetes, which is a Mounjaro use, or for heart failure, or for anyone under 18.10815

When will Zepbound be approved for teens?

No approval date is known, and the August 2026 label says safety and effectiveness have not been established in pediatric patients.15 Lilly's phase 3 SURMOUNT-ADOLESCENTS trial enrolled 160 teens aged 12 to 17.6 It reached primary completion on June 2, 2026, and had no posted results at its June 29, 2026 registry update.6 A second teen trial, SURMOUNT-ADOLESCENTS-2, was recruiting, with primary completion expected in October 2027.16

Is Zepbound legit?

Yes. Zepbound is an FDA-approved, prescription-only medicine from Eli Lilly, first approved on November 8, 2023.31 Compounded tirzepatide, which FDA has warned about, is not FDA approved.17 Unapproved tirzepatide falsely labeled 'for research purposes' and sold to consumers with dosing instructions is, according to FDA, of unknown quality.18

Does Zepbound need to be mixed before use?

No. Every Zepbound presentation holds a clear, colorless to slightly yellow solution that is ready to inject.5 For vials, the instructions only cover drawing the dose into a syringe: 0.5 mL from a single-dose vial or 0.6 mL from a multi-dose vial.19 They also say not to mix Zepbound with any other medicine.19 The label contains no reconstitution step.5

Written by D2C Peptides Editorial Team.

Pending qualified review.

Updated .

Sources

  1. Drugs@FDA: NDA 217806, Zepbound (tirzepatide) application overview. U.S. Food and Drug Administration, 2026.
  2. Zepbound Prescribing Information, revised 08/2026: Sections 12.1 Mechanism of Action and 12.2 Pharmacodynamics. Eli Lilly and Company; posted by U.S. Food and Drug Administration, 2026.
  3. FDA Approves New Medication for Chronic Weight Management (news release, November 8, 2023). U.S. Food and Drug Administration, 2023.
  4. FDA Approves First Medication for Obstructive Sleep Apnea (news release, December 20, 2024). U.S. Food and Drug Administration, 2024.
  5. Same source as 2: Sections 3 Dosage Forms and Strengths, 11 Description, 16.1 How Supplied.
  6. ClinicalTrials.gov NCT06075667: A Study of Tirzepatide (LY3298176) Once Weekly in Adolescent Participants Who Have Obesity or Overweight (SURMOUNT-ADOLESCENTS). U.S. National Library of Medicine (ClinicalTrials.gov), 2026.
  7. Same source as 2: Zepbound Medication Guide, revised 04/2026 (in the 08/2026 label file).
  8. Same source as 2: revised 08/2026 (NDA 217806/S-041): Section 1 Indications and Usage.
  9. Same source as 2: Boxed Warning, Risk of Thyroid C-Cell Tumors.
  10. Mounjaro Prescribing Information, revised 08/2026 (NDA 215866/S-044, S-045): Indications, glycemic control. Eli Lilly and Company; posted by U.S. Food and Drug Administration, 2026.
  11. Same source as 10: Indications, cardiovascular risk reduction.
  12. Zepbound official site (home page). Lilly USA, LLC, 2026.
  13. Same source as 2: Section 14.2 Obstructive Sleep Apnea Studies 5 and 6 (Tables 8 and 9).
  14. Same source as 2: Sections 2.1 and 2.2 Dose Escalation, Maintenance and Maximum Dosage.
  15. Same source as 2: Section 8 Use in Specific Populations (pregnancy, lactation, pediatric, geriatric, renal, hepatic).
  16. ClinicalTrials.gov registry query results listing NCT06439277 (SURMOUNT-ADOLESCENTS-2). U.S. National Library of Medicine (ClinicalTrials.gov), 2026.
  17. FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss: compounded drugs. U.S. Food and Drug Administration, 2026.
  18. Same source as 17: FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss (content current as of 10/01/2026): research-labeled products.
  19. Same source as 2: Zepbound multi-dose vial and single-dose vial Instructions for Use, revised January and April 2026 (in the 08/2026 label file).
  20. Same source as 2: Section 2.4 Important Administration Instructions.
  21. 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.
  22. Same source as 2: Section 10 Overdosage and Section 12.3 Pharmacokinetics.
  23. Same source as 2: Section 14.1 Weight Reduction Studies 1, 2 and 3 (Tables 2 to 5).
  24. Same source as 2: Section 14.1 Randomized Withdrawal Study 4 (Table 6).
  25. Same source as 2: Section 6.1 Clinical Trials Experience (Table 1 and text).
  26. Same source as 2: Section 4 Contraindications and Section 5.1.
  27. Same source as 2: Sections 5.2 to 5.10 Warnings and Precautions.
  28. DailyMed: ZEPBOUND and ZEPBOUND KWIKPEN (tirzepatide injection) label, updated August 28, 2026, Instructions for Use. U.S. National Library of Medicine (DailyMed), 2026.
  29. Same source as 2: Zepbound KwikPen Instructions for Use, issued January 2026 (in the 08/2026 label file).
  30. Same source as 2: Section 16.2 Storage and Handling.
  31. FDA approval letter, NDA 215866/S-052 (Mounjaro) and NDA 217806/S-050 (Zepbound), in-use temperature cycling, signed April 22, 2026. U.S. Food and Drug Administration, 2026.
  32. FDA supplement approval letter, NDA 217806/S-002 (Zepbound KwikPen), signed January 20, 2026. U.S. Food and Drug Administration, 2026.
  33. FDA supplement approval letter, NDA 217806/S-042 (safety labeling changes), signed February 25, 2026. U.S. Food and Drug Administration, 2026.
  34. FDA corrected supplement approval letter, NDA 217806/S-041 (SURPASS-CVOT labeling), action date August 26, 2026. U.S. Food and Drug Administration, 2026.
  35. Mounjaro (tirzepatide) EPAR overview, page last updated 08/10/2026. European Medicines Agency, 2026.
  36. FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize (update of December 19, 2024). U.S. Food and Drug Administration, 2026.
  37. Same source as 17: adverse event reports.