Status checked on October 6, 2026 dailymed.nlm.nih.gov
Tirzepatide (Zepbound, Mounjaro): how the dual GIP/GLP-1 agonist works, approved uses, SURMOUNT and SURPASS results, side effects and compounded versions.
Fact-checked against FDA labels and official sources; not yet reviewed by a licensed clinician. This page is education, not medical advice. Talk to your doctor before starting, stopping or changing any treatment.
Brands with this active ingredient
| Brand | Route | How often | Approved uses | Status | Manufacturer |
|---|---|---|---|---|---|
| Mounjaro (tirzepatide): approved uses and how it differs from Zepbound | Injection | Weekly | Improve glycemic control, as an adjunct to diet and exercise; Improve glycemic control, as an adjunct to diet and exercise; Reduce the risk of major adverse cardiovascular events (CV death, nonfatal heart attack, nonfatal stroke) | FDA approved for another usePrescriptionInjection | Eli Lilly |
| Mounjaro Side Effects: what the label lists, by dose, and when to get help | FDA approved for another usePrescriptionInjection | Eli Lilly | |||
| Zepbound (tirzepatide): uses, side effects, cost and FDA status | Injection | Weekly | Reduce excess body weight and maintain weight reduction long term (with reduced-calorie diet and increased physical activity); Moderate to severe obstructive sleep apnea (with reduced-calorie diet and increased physical activity) | FDA approved for weight managementPrescriptionInjection | Eli Lilly |
| Zepbound Side Effects: common, serious and how they compare | FDA approved for weight managementPrescriptionInjection | Eli Lilly |
Key takeaways
- Tirzepatide is sold as Zepbound (weight management and sleep apnea in adults with obesity) and Mounjaro (type 2 diabetes); only Zepbound is approved for weight.[1]
- In SURMOUNT-1, adults lost 15.0% to 20.9% of body weight on average over 72 weeks, versus 3.1% on placebo.[6]
- In SURMOUNT-5, average weight change was -20.2% with tirzepatide and -13.7% with semaglutide over 72 weeks.[9]
- After stopping in SURMOUNT-4, people regained 14.0% of body weight over a year, while those who continued kept losing.[7]
In short: Tirzepatide is a once-weekly injectable medicine from Eli Lilly that activates two gut-hormone receptors, GIP and GLP-1. It is sold as Zepbound, FDA approved for chronic weight management and for moderate to severe obstructive sleep apnea in adults with obesity, and as Mounjaro, FDA approved for type 2 diabetes. In the SURMOUNT-1 trial, adults without diabetes lost 15% to 21% of their body weight on average over 72 weeks, depending on dose (labels checked on 2026-10-06).
This page covers the molecule across both brands: how a dual agonist works, what the SURMOUNT and SURPASS trials found, the side effects the labels share, and the difference between approved and compounded tirzepatide.
Tirzepatide brands at a glance
| Brand | Approved for (label, checked 2026-10-06) | First approved | Weight indication |
|---|---|---|---|
| Zepbound | Weight reduction and maintenance in adults with obesity, or overweight with a weight-related condition; moderate to severe obstructive sleep apnea in adults with obesity | November 8, 2023 | Yes |
| Mounjaro | Blood sugar control in adults and children 10+ with type 2 diabetes; cardiovascular risk reduction in high-risk adults with type 2 diabetes | May 13, 2022 | No |
Both come as single-dose pens and vials and as a multi-dose KwikPen. The labels say tirzepatide should not be combined with other tirzepatide products or with any GLP-1 receptor agonist.
How a dual GIP/GLP-1 agonist works
After a meal, the gut releases two “incretin” hormones: GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). Both prompt the pancreas to release insulin when blood sugar rises. GLP-1 also slows stomach emptying and signals fullness to the brain. Tirzepatide is a single molecule that activates both receptors and lasts long enough for weekly dosing. In practice this means smaller appetite, earlier fullness and better blood sugar control. Researchers are still working out how much the GIP part adds on its own; what is measured is the overall effect in trials. Our GLP-1 medications guide puts tirzepatide in the context of the whole class, including semaglutide and the newer pills.
What the trials showed
Weight (SURMOUNT). In SURMOUNT-1, 2,539 adults with obesity or overweight and no diabetes took weekly tirzepatide or placebo for 72 weeks. Average weight change was -15.0% at 5 mg, -19.5% at 10 mg and -20.9% at 15 mg, versus -3.1% with placebo. SURMOUNT-4 tested stopping: after a 36-week lead-in with an average loss of 20.9%, people switched to placebo regained 14.0% over the next year, while those who continued lost another 5.5%.
Sleep apnea (SURMOUNT-OSA). In adults with obesity and moderate to severe sleep apnea, the number of breathing interruptions per hour fell by about 25 to 29 with tirzepatide over 52 weeks, compared with about 5 with placebo.
Head to head with semaglutide. In SURPASS-2, in type 2 diabetes, tirzepatide lowered HbA1c and weight more than semaglutide 1 mg over 40 weeks. In SURMOUNT-5, in 751 adults with obesity but no diabetes, average weight change at 72 weeks was -20.2% with tirzepatide and -13.7% with semaglutide at the highest doses people could tolerate. Both trials were open label. The semaglutide vs tirzepatide comparison explains what that does and does not mean for any one person.
Heart (SURPASS-CVOT). In 13,165 adults with type 2 diabetes and atherosclerotic cardiovascular disease, major cardiovascular events occurred in 12.2% on tirzepatide and 13.1% on dulaglutide, meeting the test for noninferiority but not superiority.
Side effects shared across brands
Both labels list digestive effects as the most common: nausea, diarrhea, vomiting, constipation, abdominal pain and indigestion, mostly during dose increases. In the Zepbound weight trials, nausea affected 25% to 29% of people (8% on placebo); in the Mounjaro diabetes trials, 12% to 18% (4%). Both carry a boxed warning about thyroid C-cell tumors seen in rats and are not used with a personal or family history of medullary thyroid carcinoma or MEN 2. Shared warnings include pancreatitis, gallbladder disease, low blood sugar with insulin or sulfonylureas, kidney injury from dehydration, severe digestive reactions, allergic reactions, diabetic eye complications and aspiration during anesthesia. Both labels also advise people on birth-control pills to use a non-oral or added barrier method for four weeks after starting and after each dose increase. See GLP-1 side effects.
Compounded tirzepatide vs approved tirzepatide
While tirzepatide was on the FDA drug shortage list, compounding was allowed under certain conditions. The FDA first removed it from the shortage list on October 2, 2024 and, after a court-ordered review, confirmed the shortage was resolved on December 19, 2024, giving outsourcing facilities until March 19, 2025 to stop. In 2026 the FDA proposed excluding tirzepatide from the list of bulk substances outsourcing facilities may use. Compounded products are not FDA approved, and the FDA reports adverse events linked to them. Details are in compounded GLP-1s.
Cost
On 2026-10-06, Lilly listed Zepbound KwikPen self-pay prices from $299 a month for the starting dose to $449 a month for the higher doses with on-time refills, and a $25 savings-card price for people whose commercial insurance covers it. See Zepbound cost and the GLP-1 cost comparison. Lifestyle remains part of every label’s instructions; our strength training guide helps protect muscle while weight comes down.
FDA status and approved uses
| Indication | Labeled population | For weight | Approved | Source |
|---|---|---|---|---|
| Chronic weight management (Zepbound) | Adults with obesity, or overweight with at least one weight-related comorbid condition | Yes | November 8, 2023 | Source |
| Moderate to severe obstructive sleep apnea (Zepbound) | Adults with obesity | No | December 20, 2024 | Source |
| Glycemic control in type 2 diabetes (Mounjaro) | Adults; pediatric patients 10+ since 2025-12-19 | No | May 13, 2022 | Source |
From the FDA label. Who a medicine is labeled for is not the same as whether it fits you; only a clinician can decide that.
How it is taken (in general)
Once weekly under the skin. Both labels describe a starting dose for 4 weeks, then increases at least 4 weeks apart to a maintenance dose. Doses and maximums depend on the brand and the condition; follow your prescriber.
This is what the label describes in general, never a personal dose or schedule. Follow your prescriber.
What studies showed
| Trial | Population | Duration | Outcome as reported |
|---|---|---|---|
| SURMOUNT-1 NCT04184622 | 2,539 adults with obesity or overweight, no diabetes | 72 weeks | -15.0%, -19.5%, -20.9% (5, 10, 15 mg) vs -3.1% placebo.[6] |
| SURMOUNT-4 NCT04660643 | 670 adults after a 36-week lead-in | 52 weeks after randomization | Continued -5.5% vs +14.0% after switching to placebo.[7] |
| SURMOUNT-OSA NCT05412004 | Adults with obesity and moderate to severe sleep apnea | 52 weeks | AHI -25.3 and -29.3 vs -5.3 and -5.5 events per hour.[8] |
| SURMOUNT-5 NCT05822830 | 751 adults with obesity, no type 2 diabetes | 72 weeks | -20.2% tirzepatide vs -13.7% semaglutide (open label).[9] |
| SURPASS-2 NCT03987919 | 1,879 adults with type 2 diabetes | 40 weeks | Superior HbA1c reduction vs semaglutide 1 mg; extra weight loss 1.9 to 5.5 kg by dose.[10] |
| SURPASS-CVOT NCT04255433 | 13,165 adults with type 2 diabetes and atherosclerotic cardiovascular disease | Event-driven | MACE 12.2% vs 13.1% with dulaglutide (hazard ratio 0.92), noninferior.[11] |
Average results from trials; individual results vary. Results from different trials cannot be compared directly.
Side effects
| Common side effect | How often (label) |
|---|---|
| Nausea | 25% to 29% vs 8% (Zepbound); 12% to 18% vs 4% (Mounjaro) |
| Diarrhea | 19% to 23% vs 8% (Zepbound); 12% to 17% vs 9% (Mounjaro) |
| Vomiting | 8% to 13% vs 2% (Zepbound); 5% to 9% vs 2% (Mounjaro) |
| Constipation | 11% to 17% vs 5% (Zepbound); 6% to 7% vs 1% (Mounjaro) |
Serious risks
- Thyroid C-cell tumors (boxed warning, rats)
- Acute pancreatitis
- Acute gallbladder disease
- Hypoglycemia with insulin or sulfonylureas
- Acute kidney injury
- Severe gastrointestinal reactions
- Diabetic retinopathy complications
- Pulmonary aspiration during anesthesia or deep sedation
Warnings and who should not use it
Boxed warning
Both tirzepatide products carry a boxed warning: tirzepatide causes thyroid C-cell tumors in rats; it is unknown whether it causes thyroid C-cell tumors, including medullary thyroid carcinoma (MTC), in humans. Contraindicated with a personal or family history of MTC or with MEN 2.
Who should not use it (per the label)
- Personal or family history of medullary thyroid carcinoma (MTC) or MEN 2
- Known serious hypersensitivity to tirzepatide or excipients
Interactions, pregnancy and breastfeeding
| Drug or class | What the label says |
|---|---|
| Oral hormonal contraceptives | Use a non-oral or added barrier method for 4 weeks after starting and after each dose increase (both labels). |
Stopping and keeping results
Trials show that weight often returns after these medicines are stopped. Plan any change with your prescriber. Stopping a GLP-1: what trials show and how people keep results
Compounded and counterfeit versions
Compounded semaglutide and tirzepatide are not FDA approved: the FDA does not review them for safety, quality or effectiveness. Counterfeit pens and "research peptides" sold online have caused harm. Buy only from a licensed pharmacy with a prescription.
Same class
FDA approved for weight managementPrescriptionInjectionZepbound (tirzepatide): uses, side effects, cost and FDA statusTirzepatide: how the dual GIP/GLP-1 drug works (Zepbound, Mounjaro) · Injection · Weekly
FDA approved for another usePrescriptionInjectionMounjaro (tirzepatide): approved uses and how it differs from ZepboundTirzepatide: how the dual GIP/GLP-1 drug works (Zepbound, Mounjaro) · Injection · WeeklyCompare with
Non-drug approaches
FDA approved for weight managementPrescriptionInjectionSemaglutide: one ingredient, several brandsInjection · Daily, Weekly
FDA approved for weight managementPrescriptionPillOrforglipron: the small-molecule GLP-1 pill and its current statusPill (tablet) · Daily
FDA approved for weight managementPrescriptionInjectionLiraglutide: the daily GLP-1 (Saxenda, Victoza) and genericsInjection · Daily
How to Lose Weight: every proven approach in one placeHow to lose weight: the calorie deficit, food, activity, sleep and habits with the best evidence,…Research mentioning it
Related guides
GLP-1 Medications: how they work and which are approved for weightGLP-1 medications explained: what GLP-1 is, how the drugs work, which brands are FDA approved for…
Compounded Semaglutide and Tirzepatide: what FDA says and the risksCompounded semaglutide and tirzepatide explained: not FDA approved, the dated shortage history, FDA safety reports, counterfeit…
GLP-1 Side Effects: common, serious and how they are managedGLP-1 side effects from the FDA labels: common digestive effects by brand, serious risks, the thyroid…Tools for this topic
Questions to ask your doctor or pharmacist
- Does the condition we are treating match Zepbound, Mounjaro or neither?
- How do the expected benefits compare with semaglutide or a pill for someone with my history?
- What side effects should I watch for during dose increases, and when should I call?
- What should I do about contraception and my other medicines?
- How long might I need to take it, and what happens to my weight if I stop?
Frequently asked questions
What is the difference between tirzepatide and semaglutide?
Semaglutide acts on the GLP-1 receptor; tirzepatide acts on both GIP and GLP-1 receptors. In the SURMOUNT-5 head-to-head trial in adults with obesity, average weight loss was larger with tirzepatide. Side effects are similar in kind.
Is tirzepatide available as a generic?
As of 2026-10-06 we found no FDA-approved generic tirzepatide; the approved products are Zepbound and Mounjaro. Compounded tirzepatide is not a generic and is not FDA approved.
Is there a tirzepatide pill?
No tirzepatide pill is approved. Lilly's approved weight pill is Foundayo, which contains a different molecule, orforglipron.
Can tirzepatide affect birth control?
Yes, it may make oral contraceptives less reliable while doses increase. Both labels advise a non-oral or added barrier method for 4 weeks after starting and after each increase.
Official sources
References
- ZEPBOUND (tirzepatide) injection: prescribing information. Eli Lilly and Company, via DailyMed, 2026. (accessed October 7, 2026) Drug label
- MOUNJARO (tirzepatide) injection: prescribing information. Eli Lilly and Company, via DailyMed, 2026. (accessed October 7, 2026) Drug label
- Drugs@FDA: Zepbound, NDA 217806. U.S. Food and Drug Administration. (accessed October 7, 2026) Government page
- Drugs@FDA: Mounjaro, NDA 215866, approval history. U.S. Food and Drug Administration. (accessed October 6, 2026) Government page
- FDA Approves First Medication for Obstructive Sleep Apnea. U.S. Food and Drug Administration, 2024. (accessed October 7, 2026) Government page
- Jastreboff AM, Aronne LJ, Ahmad NN, et al.. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). New England Journal of Medicine, 2022. doi:10.1056/NEJMoa2206038 · PMID 35658024 · NCT04184622 (accessed October 7, 2026) Randomized trial
- Aronne LJ, Sattar N, Horn DB, et al.. Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial. JAMA, 2024. doi:10.1001/jama.2023.24945 · PMID 38078870 · NCT04660643 (accessed October 7, 2026) Randomized trial
- Malhotra A, Grunstein RR, Fietze I, et al.. Tirzepatide for the Treatment of Obstructive Sleep Apnea and Obesity (SURMOUNT-OSA). New England Journal of Medicine, 2024. doi:10.1056/NEJMoa2404881 · PMID 38912654 · NCT05412004 (accessed October 6, 2026) Randomized trial
- Aronne LJ, Horn DB, le Roux CW, et al.. Tirzepatide as Compared with Semaglutide for the Treatment of Obesity (SURMOUNT-5). New England Journal of Medicine, 2025. doi:10.1056/NEJMoa2416394 · PMID 40353578 · NCT05822830 (accessed October 6, 2026) Randomized trial
- Frias JP, Davies MJ, Rosenstock J, et al.. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). New England Journal of Medicine, 2021. doi:10.1056/NEJMoa2107519 · PMID 34170647 · NCT03987919 (accessed October 7, 2026) Randomized trial
- Nicholls SJ, Pavo I, Bhatt DL, et al.. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes (SURPASS-CVOT). New England Journal of Medicine, 2025. doi:10.1056/NEJMoa2505928 · PMID 41406444 · NCT04255433 (accessed October 6, 2026) Randomized trial
- Resolution of tirzepatide injection product shortage (decision memorandum). U.S. Food and Drug Administration, 2024. (accessed October 6, 2026) Government page
- FDA proposes to exclude semaglutide, tirzepatide and liraglutide from 503B bulks list. U.S. Food and Drug Administration, 2026. (accessed October 6, 2026) Government page
- Zepbound coverage and savings. Eli Lilly and Company. (accessed October 6, 2026) Other
Facts checked on October 6, 2026
Educational information, not medical advice. Talk with a qualified healthcare professional about your own situation. In an emergency call 911.