Tirzepatide vs Orforglipron

Quick read · 5 min

Last reviewed: June 2026Based on 2 clinical trialsEvery claim linked to source

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 68-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

Orforglipron is significantly cheaper than tirzepatide injection. With insurance, both are typically $25–50/month.

Foundayo (lowest dose)(orforglipron)~$149/mo
Foundayo (highest dose)(orforglipron max)~$349/mo
Zepbound(tirzepatide injection, via LillyDirect)~$1,086/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. The comparison above uses data from these separate studies, which is less definitive than a direct trial.

Side effects comparison

From each drug's main weight loss trial. Both cause similar stomach side effects during dose escalation.

Nausea
Tirzepatide31%
Foundayo33%
Diarrhea
Tirzepatide23%
Foundayo18%
Vomiting
Tirzepatide18%
Foundayo16%
Constipation
Tirzepatide12%
Foundayo10%
Quit due to side effects
Tirzepatide6%
Foundayo8%

Side effect profiles are remarkably similar. Tirzepatide has slightly more diarrhea; orforglipron has a slightly higher quit rate. Both peak in weeks 2–8 and usually fade.

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 — more appetite reduction than GLP-1 alone
Orforglipron — GLP-1 only
Activates GLP-1 only — same pathway as semaglutide and other GLP-1 drugs

Side effects

Nausea (both drugs)31–33%
Tirzepatide (slightly lower)~31%
Peaks at weeks2–8

Usually fades by week 8–12 in both drugs

Key trade-off

Tirzepatide offers higher weight loss through its dual-hormone mechanism but requires weekly injections and costs 6–7x more self-pay. Orforglipron is a convenient daily pill with much lower cost, but produces lower weight loss. Neither is universally better — discuss with your doctor based on your needle comfort, budget, and weight loss goals.

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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.