glp1versus

Byetta vs Mounjaro

exenatide (GLP-1 receptor agonist) vs tirzepatide (Dual GIP and GLP-1 receptor agonist) — a complete side-by-side comparison.

AstraZenecaEli Lilly

Byetta weight loss

2.8%

Mounjaro weight loss

22.5%

Byetta dosing

Twice daily (within 60 min before meals)

Mounjaro dosing

Once weekly

Reviewed by Dr. Elena Vance, DOLast reviewed 13 sources cited

Quick Summary

Byetta (exenatide) and Mounjaro (tirzepatide) are both incretin-based therapies. In clinical trials, Mounjaro showed greater weight loss (22.5% vs 2.8%).

See the comparison table below for detailed side-by-side data.

Byetta vs Mounjaro: Full Comparison

FeatureByetta(exenatide)Mounjaro(tirzepatide)
Active Ingredientexenatidetirzepatide
Drug ClassGLP-1 receptor agonistDual GIP and GLP-1 receptor agonist
ManufacturerAstraZenecaEli Lilly
FDA Approved2005-04-282022-05-13
Approved Indications
  • Type 2 diabetes mellitus (adjunct to diet and exercise)
  • Type 2 diabetes mellitus (adjunct to diet and exercise)
Routesubcutaneous injectionsubcutaneous injection
FrequencyTwice daily (within 60 min before meals)Once weekly
Starting Dose5 mcg twice daily2.5 mg weekly
Maintenance Dose10 mcg twice daily5 mg, 10 mg, or 15 mg weekly
Max Dose10 mcg twice daily15 mg weekly
Weight Loss (%)2.8%22.5%
A1C Reduction0.8%2.4%
Key TrialAC2993 Phase 3 (30 weeks)SURMOUNT-1 (72 weeks)
List Price$800-$900/month$1,023-$1,176/month
With Insurance$25-$100/month (varies by plan)$25-$150/month (varies by plan)
Savings CardLimited savings programs available$25/month (Lilly savings card, commercially insured)

Side Effects: Byetta vs Mounjaro

Side EffectByettaMounjaro
Nausea44%12-18%
Vomiting13%5-9%
Diarrhea13%12-17%
Headache9%Not reported
Dizziness9%Not reported
Dyspepsia6%5-8%
Jittery feeling4%Not reported
Pancreatitis (rare)<1%<0.5%
Decreased appetiteNot reported5-11%
ConstipationNot reported6-7%
Abdominal painNot reported5-6%
Injection site reactionNot reported3-5%

Severity scale: 1 (mild) to 5 (serious). Based on FDA prescribing information and clinical trial data.

Related Comparisons

Byetta vs OzempicMounjaro vs OzempicByetta vs WegovyMounjaro vs WegovyByetta vs ZepboundMounjaro vs ZepboundByetta vs RybelsusMounjaro vs Rybelsus

Frequently Asked Questions

Sources & References

FDA & Regulatory

  1. Byetta FDA Drugs@FDA approval record — FDA
  2. Mounjaro FDA Drugs@FDA approval record — FDA

Clinical Trial Records

  1. AC2993 Phase 3 clinical trial record — ClinicalTrials.gov
  2. SURMOUNT-1 clinical trial record — ClinicalTrials.gov

Peer-Reviewed Literature

  1. DeFronzo RA et al. Effects of Exenatide on Glycemic Control and Weight Over 30 Weeks in Metformin-Treated Patients with Type 2 Diabetes. Diabetes Care 2005;28:1092-1100 — Diabetes Care
  2. Jastreboff AM et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med 2022;387:205-216 — New England Journal of Medicine
  3. Rosenstock J et al. Efficacy and safety of a novel dual GIP and GLP-1 receptor agonist tirzepatide in people with type 2 diabetes (SURPASS-1). Lancet 2021;398:143-155 — The Lancet

Manufacturer Information

  1. Bydureon/Byetta patient website (AstraZeneca) — AstraZeneca
  2. Mounjaro patient and healthcare provider website — Eli Lilly
  3. Lilly press release: Zepbound superior weight loss over Wegovy in SURMOUNT-5 (May 11, 2025) — Eli Lilly Investor Relations

Professional Guidelines

  1. ADA Standards of Care in Diabetes (pharmacologic therapy section) — American Diabetes Association

Reference Entries

  1. Exenatide entry on Wikipedia — Wikipedia
  2. Tirzepatide entry on Wikipedia — Wikipedia

This content is for informational purposes only and is not medical advice. Always consult your healthcare provider before making medication decisions. See our full medical disclaimer.