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The Peptide Effect
approvedWeight Loss & Diabetes

Tirzepatide

Also known as: Mounjaro, Zepbound, LY3298176

Tirzepatide is a first-in-class dual GIP/GLP-1 receptor agonist approved by the FDA for type 2 diabetes (as Mounjaro) and chronic weight management (as Zepbound). In landmark clinical trials, it demonstrated weight loss of up to 20-25% of body weight, making it one of the most effective anti-obesity medications ever developed.

Key Facts

Mechanism
Tirzepatide simultaneously activates both the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptors. This dual agonism enhances glucose-dependent insulin secretion from pancreatic beta cells, suppresses glucagon release from alpha cells, slows gastric emptying to promote satiety, and reduces appetite through hypothalamic signaling. The GIP component may also enhance fat metabolism and improve the tolerability of GLP-1-mediated effects.
Research Status
approved
Half-Life
~5 days
Molecular Formula
C₂₂₅H₃₄₈N₄₈O₆₈
Primary Use
Weight Loss & Diabetes
Table of Contents

Benefits

  • Significant weight loss of 20-25% body weight in clinical trials (SURMOUNT program)strong
  • Superior glycemic control with HbA1c reductions of 2.0-2.6% in type 2 diabetesstrong
  • Improved insulin sensitivity and beta-cell functionstrong
  • Reduced cardiovascular risk markers including triglycerides and blood pressuremoderate
  • Potential reduction in liver fat content (MASH/NAFLD improvement)moderate
  • Improvements in obstructive sleep apnea severity (SURMOUNT-OSA)moderate

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection (Mounjaro)2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mgOnce weeklyStart at 2.5 mg for 4 weeks, then escalate by 2.5 mg every 4 weeks as tolerated. For type 2 diabetes.
Subcutaneous injection (Zepbound)2.5 mg → 5 mg → 7.5 mg → 10 mg → 12.5 mg → 15 mgOnce weeklySame escalation schedule as Mounjaro. FDA approved specifically for chronic weight management in adults with BMI ≥30 or ≥27 with comorbidity.
Subcutaneous injection (maintenance)5 mg, 10 mg, or 15 mgOnce weeklyMaintenance dose determined by individual tolerability and treatment response. Can be injected in abdomen, thigh, or upper arm.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Nausea, especially during dose escalation periodscommon
  • Diarrhea and loose stoolscommon
  • Vomiting, typically decreasing over timecommon
  • Injection site reactions (redness, itching, pain)common
  • Decreased appetite and early satietycommon
  • Pancreatitis (acute inflammation of the pancreas)serious
  • Thyroid C-cell tumors observed in rodent studies — contraindicated in patients with personal or family history of medullary thyroid carcinoma or MEN 2serious
  • Gallbladder-related events including cholelithiasisrare

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Frequently Asked Questions

How much does tirzepatide (Mounjaro/Zepbound) cost without insurance?
Without insurance, Mounjaro and Zepbound cost approximately $1,000-$1,200 per month at retail pharmacies. Manufacturer savings cards may reduce the cost for commercially insured patients. Compounded versions have been available at lower cost, though the FDA and Eli Lilly have taken steps to limit compounding. Always consult a licensed healthcare provider before starting any medication.
How does tirzepatide compare to semaglutide (Ozempic/Wegovy)?
Tirzepatide is a dual GIP/GLP-1 agonist while semaglutide targets only GLP-1. In head-to-head trials (SURPASS-2), tirzepatide at 15 mg produced greater weight loss (~12.4 kg vs ~6.2 kg) and HbA1c reduction compared to semaglutide 1 mg. However, individual responses vary, and the best medication depends on your specific medical situation. Consult your physician for personalized guidance.
How long do I need to take tirzepatide?
Current evidence suggests tirzepatide is intended as a long-term or indefinite treatment. The SURMOUNT-4 trial showed that patients who discontinued tirzepatide after 36 weeks regained approximately two-thirds of their lost weight within one year. Your healthcare provider can help determine the appropriate treatment duration based on your individual goals and health status.
Does insurance cover tirzepatide for weight loss?
Insurance coverage varies significantly. Most commercial plans cover Mounjaro for type 2 diabetes but many do not cover Zepbound for weight loss alone. Medicare Part D does not currently cover anti-obesity medications. Some employer-sponsored plans and state Medicaid programs have begun adding coverage. Check with your specific insurance plan and discuss prior authorization options with your prescriber.
Are compounded versions of tirzepatide safe and legal?
Compounded tirzepatide exists in a complex legal and regulatory space. The FDA placed tirzepatide on and then removed it from the drug shortage list, which affects compounding pharmacies' ability to produce it. Compounded medications are not FDA-approved and may vary in potency, sterility, and quality. If considering a compounded version, only use a 503A or 503B registered compounding pharmacy. This is not medical advice — consult your healthcare provider.

References

  1. 1
    Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1)(2022)PubMed ↗
  2. 2
    Tirzepatide versus semaglutide once weekly in patients with type 2 diabetes (SURPASS-2)(2021)PubMed ↗
  3. 3
    Tirzepatide once weekly for the treatment of type 2 diabetes (SURPASS-1)(2021)PubMed ↗
  4. 4
    Effect of tirzepatide on body weight after treatment discontinuation (SURMOUNT-4)(2023)PubMed ↗

Last updated: 2026-02-14