Orforglipron vs Zepbound: Daily Pill vs Weekly Shot for Weight Loss

By DoseGauge Editorial · Updated 2026-06-13 · 6 min read

Both orforglipron and tirzepatide are FDA-approved for chronic weight management, and both are made by Eli Lilly. Orforglipron (sold as Foundayo) is a once-daily oral pill. Zepbound (tirzepatide) is a once-weekly subcutaneous injection. In their respective phase 3 obesity trials, Zepbound produced a larger average weight loss than orforglipron at the doses studied. The trade-off is form factor: a daily pill with no injections versus a weekly shot that showed a larger average reduction in those trials. That is a factual comparison, not a recommendation. A clinician matches a drug and dose to an individual.

Form and routine

The most immediate difference is how each drug is taken. Orforglipron is swallowed as a tablet once a day. It is a non-peptide small molecule, so it survives digestion without needing an injection, and the Foundayo prescribing information does not require it to be taken with food or water restrictions. That means no fasting window, no injection site management, and no pen device to carry or refrigerate.

Zepbound is a once-weekly subcutaneous injection delivered by an auto-injector pen. It is injected under the skin of the abdomen, thigh, or upper arm, and the pen is typically refrigerated. The weekly cadence means fewer doses per year, but each dose is an injection.

For someone who cannot tolerate injections, or who wants a simpler daily-pill routine, orforglipron removes the injection entirely. For someone who prefers one dose per week over a daily reminder, Zepbound's cadence may fit better. Neither choice is universally better. The right choice depends on the individual.

Dosing

The approved label for orforglipron (Foundayo) starts at 0.8 mg daily and titrates through monthly steps to a maximum of 17.2 mg daily. For the full titration schedule and a dose conversion tool, see the orforglipron dosing schedule. The Zepbound label starts at 2.5 mg weekly and titrates in 2.5 mg increments to a maximum of 15 mg weekly.

The milligram scales are not comparable across the two drugs. A dose number from one cannot be applied to the other. Each drug has its own conversion arithmetic: for dose-to-volume calculations on either drug, use the drug's own calculator.

For the mechanism behind why orforglipron (a single GLP-1 agonist) and tirzepatide (a dual GIP and GLP-1 agonist) differ at the receptor level, see orforglipron vs tirzepatide.

What the trials showed

ATTAIN-1 was a phase 3, randomized, double-blind trial in 3,127 adults with obesity but without diabetes. It studied orforglipron at 6 mg, 12 mg, and 36 mg versus placebo over 72 weeks. The mean body-weight reduction was 11.2% at the 36 mg top dose (the treatment-regimen estimand, the primary analysis basis), versus 2.1% with placebo.

SURMOUNT-1 was a phase 3, randomized, double-blind trial studying tirzepatide at 5 mg, 10 mg, and 15 mg versus placebo over 72 weeks in adults with obesity or overweight plus at least one weight-related comorbidity (without diabetes). At the 15 mg dose, mean body-weight reduction was about 20.9% on the same treatment-regimen estimand basis.

Three caveats matter when reading those numbers side by side. First, these are entirely separate trials with different populations, protocols, and dose ranges. There is no head-to-head comparison between the two drugs. Second, the ATTAIN-1 doses (6 mg, 12 mg, 36 mg) differ from the approved Foundayo label doses (0.8 to 17.2 mg daily), so the 11.2% figure is not the result you would expect on the approved titration schedule. The same caveat applies to the Zepbound label: the trial dose of 15 mg does align with the label maximum, but individual results vary and the trial population had specific enrollment criteria. Third, trial averages do not predict any individual's outcome.

Side effects at a glance

Both drugs have a gastrointestinal-predominant side-effect profile. Nausea, diarrhea, and vomiting are the most commonly reported adverse events for each, and both are generally described as mild to moderate and occurring more often during dose escalation.

Both labels also carry the same class-level boxed warning: thyroid C-cell tumors were observed in rodent studies, and both drugs are contraindicated in people with a personal or family history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia type 2 (MEN 2). The human relevance of the rodent finding is described in both labels as not determined. For the full detail on warnings, refer to the respective prescribing information linked in the citations above.

FAQ

Which loses more weight, orforglipron or Zepbound?

In their respective phase 3 obesity trials, Zepbound (tirzepatide) showed a larger average weight loss: about 20.9% at 15 mg over 72 weeks in SURMOUNT-1, versus about 11.2% at the top trial dose (36 mg) of orforglipron over 72 weeks in ATTAIN-1. Both figures are treatment-regimen estimands and come from separate trials, not a direct comparison. The doses studied in each trial also differ from the approved label doses. A larger trial average does not mean every person on Zepbound will lose more weight than every person on orforglipron.

Is Zepbound a pill?

No. Zepbound (tirzepatide) is a subcutaneous injection delivered with an auto-injector pen, administered once weekly. Orforglipron (Foundayo) is the oral pill: a once-daily tablet that does not require an injection.

Are orforglipron and Zepbound both tirzepatide?

No. Zepbound is the brand name for tirzepatide, a dual GIP and GLP-1 receptor agonist. Orforglipron is a different molecule entirely: a non-peptide small molecule that is a single GLP-1 receptor agonist. They share the same manufacturer (Eli Lilly) and the same broad therapeutic goal, but they have different chemical structures, different receptor targets, and different approved dose ranges.

Can I switch from Zepbound to the orforglipron pill?

Switching between these treatments is a clinical decision. The two drugs are different molecules with different mechanisms, very different milligram scales, and different titration schedules. The approved labels do not provide a conversion or crossover regimen, and the doses are not interchangeable. Any change in treatment would involve re-titration under medical supervision. That conversation belongs with your prescriber.

Informational and educational only. Not medical advice. DoseGauge computes from the values you enter and does not recommend a dose. Talk to a licensed clinician before using any peptide or GLP-1 medication.