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Tirzepatide vs Orforglipron

Last reviewed: September 2026Based on 2 clinical trials

A weekly injection versus a daily pill, both from Eli Lilly. Tirzepatide is Zepbound/Mounjaro. Orforglipron is Foundayo. Here is how they compare in clinical data.

Weight loss at maximum dose

Separate trials — no head-to-head data exists. Tirzepatide from a 72-week trial; orforglipron from a 72-week trial.

Zepbound / Mounjaro(tirzepatide)20.9%(~50 lbs)
Foundayo(orforglipron)12.4%(~30 lbs)
For a 240 lb person. Averages from separate studies. Individual results vary substantially.

Monthly cost self-pay

Self-pay prices are set by each manufacturer's own savings programme. With eligible commercial insurance, both drugs' savings cards price them at about $25/month.

Foundayo (lowest dose)(orforglipron)~$149/mo
Foundayo (highest dose)(orforglipron max)~$349/mo
Zepbound (lowest dose)(tirzepatide injection, via LillyDirect)~$299/mo
Zepbound (highest dose)(tirzepatide injection, via LillyDirect)~$449/mo
List prices and manufacturer self-pay programs. Insurance coverage varies.

No head-to-head trial exists. Tirzepatide data comes from a 72-week Eli Lilly trial. Orforglipron data comes from two separate Eli Lilly trials, each 72 weeks. The comparison above uses data from these separate studies, which is less definitive than a direct trial.

Side effects comparison

From each drug's own trial (SURMOUNT-1 for tirzepatide, ATTAIN-1 for orforglipron) — not a head-to-head comparison.

Nausea
Tirzepatide31%
Foundayo33%
Diarrhea
Tirzepatide23%
Foundayo15%
Vomiting
Tirzepatide18%
Foundayo19%
Constipation
Tirzepatide12%
Foundayo18%
Individual reactions vary. Side effects are typically reported during a trial's dose-escalation period and often fade with continued use.

Beyond weight loss

Form

  • Tirzepatide — Once-weekly subcutaneous injection — no food timing restrictions
  • Orforglipron — Once-daily pill — take anytime with or without food, no injection needed

How they work

  • Tirzepatide — dual agonist — Activates both GIP and GLP-1 receptors, two separate hunger-signaling pathways
  • Orforglipron — GLP-1 only — Activates GLP-1 only — same pathway as semaglutide and other GLP-1 drugs

Side effects

  • Nausea — tirzepatide (SURMOUNT-1)31%
  • Nausea — orforglipron (ATTAIN-1)33%
  • Typically peaks at weeks2–8

Usually fades by week 8–12 in both drugs

Key trade-off

In separate trials, participants on the highest dose of tirzepatide lost 20.9% of their body weight on average, and participants on the highest dose of orforglipron lost 12.4% — no trial has compared the two directly. Tirzepatide is a weekly injection; self-pay via LillyDirect is $299–$449/month depending on dose. Orforglipron is a daily pill; self-pay is $149–$349/month depending on dose. Neither is universally better — discuss with your doctor based on your needle comfort, budget, and weight loss goals.

Common questions

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Medical disclaimer: This website is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any treatment. Prices shown are United States self-pay or list prices and vary by insurance and country.