Adverse effect · Orforglipron

How common is GI side effects with Orforglipron?

A
Grade A — established in humansPhase 3 programme · effect size: moderate · adverse
Short answerEstablished in humans. Phase 3 programme point the same way: a moderate effect. The familiar incretin profile. In ATTAIN-1, adverse events caused 5.3–10.3% of participants to stop, against 2.7% on placebo. In ACHIEVE-4, gastrointestinal events were reported in 62.1% on orforglipron against 14.2% on insulin glargine.

What the studies show

The familiar incretin profile. In ATTAIN-1, adverse events caused 5.3–10.3% of participants to stop, against 2.7% on placebo. In ACHIEVE-4, gastrointestinal events were reported in 62.1% on orforglipron against 14.2% on insulin glargine.

“The most common adverse events with orforglipron were gastrointestinal effects, which were mostly mild to moderate.”

Verbatim, from the abstractWharton S, et al. Orforglipron, an oral small-molecule GLP-1 receptor agonist for obesity treatment (ATTAIN-1). N Engl J Med, 2025;393:1796–1806

Several well-run randomised trials in people, pointing the same way. You can plan around this. It still says nothing about whether the effect is worth the side effects for you.

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    Klein KR, et al. Cardiovascular safety of orforglipron versus insulin glargine in adults with type 2 diabetes at increased cardiovascular risk (ACHIEVE-4): a phase 3, event-driven, randomised, open-label, non-inferiority, active comparator trial.Lancet, 2026 (online 30 Sep)2,749 randomised, 317 sites, median follow-up 2 years; MACE-4 hazard ratio 0.84 (95% CI 0.59–1.20), non-inferiority margin 1.8. NCT05803421.

In context

Orforglipron (Foundayo) is a once-daily tablet that activates the GLP-1 receptor. It is not a peptide — it is a small molecule, which is why it survives digestion and needs no injection, refrigeration or food restriction. Its phase 3 programme is published: about 11% average weight loss over 72 weeks in obesity, and HbA1c reductions of roughly 1.5 points in early type 2 diabetes. The FDA approved it for weight management on 1 April 2026. The effect is smaller than injected tirzepatide or semaglutide; the delivery is far easier.

Orforglipron is approved (rx) — united states. Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is Orforglipron proven to cause GI side effects?
Yes, as far as human trials can show it: Phase 3 programme. LYO grades this outcome A.
What studies are behind the grade?
The familiar incretin profile. In ATTAIN-1, adverse events caused 5.3–10.3% of participants to stop, against 2.7% on placebo. In ACHIEVE-4, gastrointestinal events were reported in 62.1% on orforglipron against 14.2% on insulin glargine.
Is Orforglipron approved for this?
Orforglipron is an approved medicine (Approved (Rx) — United States); whether this particular outcome is a licensed indication is stated on the compound page's regulation section.

Other outcomes for Orforglipron

Written and maintained by LYO Research — how pages are written and checked. Reviewed 7 October 2026. Grades count human evidence only; see how LYO grades. Not medical advice. Correct this page →