Retatrutide vs Orforglipron: The Short Answer
Counted the same way, retatrutide 12 mg reduced weight by 25.0% over 80 weeks in its main Phase 3 trial, against 11.1% over 72 weeks for orforglipron 17.2 mg, the highest approved dose. The two have never been tested against each other, and the trials differed in length and participants.
They are different medicines from the same developer. Orforglipron, sold in the US as Foundayo, is a once-daily pill that acts on the GLP-1 receptor; the FDA approved it for weight management on April 1, 2026. Retatrutide is a once-weekly injection that acts on GIP, GLP-1 and glucagon receptors; it is investigational and not approved.
Weight Loss in the Phase 3 Trials
Comparing medicines from separate trials is only meaningful when the results are counted the same way. Both figures below use the treatment-regimen estimand, which counts everyone randomized, including people who stopped treatment, in adults with obesity or overweight and without diabetes.
On this basis, the highest dose of retatrutide reduced weight by about two and a quarter times as much as the highest approved dose of orforglipron. That ratio is a cross-trial comparison: TRIUMPH-1 lasted 80 weeks and ATTAIN-1 lasted 72, and the participants were not the same. Only a head-to-head trial could show the true difference.
The announcements for both medicines also use a second, larger figure that estimates the result if everyone had stayed on treatment: 28.3% for retatrutide 12 mg and 12.4% for orforglipron's highest dose. These two efficacy-estimand figures should be compared only with each other, not with the figures in the table.
In people with type 2 diabetes, the orforglipron label reports 9.6% weight loss with 17.2 mg over 72 weeks in a second trial, compared with 2.5% on placebo (counting everyone randomized). Its developer reports 20.8% for retatrutide 12 mg over 80 weeks in TRIUMPH-2, using the efficacy estimand, so these two are not on the same basis.
Pill vs Injection
Orforglipron is taken by mouth once a day, with or without food, according to its US label. Retatrutide is given as an injection under the skin once a week in its trials. Orforglipron is a small-molecule, non-peptide medicine, which is what allows it to be taken by mouth.
Side Effects
Both medicines mainly cause gastrointestinal side effects, which were generally more common at higher doses.
The figures come from different trials of different lengths, so they show the type of side effects rather than a reliable comparison of how often they occur. Retatrutide's trials also reported dysesthesia, an abnormal skin sensation, in 12.5% of people on 12 mg in TRIUMPH-1, compared with 0.9% on placebo. Orforglipron's label carries a boxed warning about the risk of thyroid C-cell tumors, the same boxed warning carried by other GLP-1-based medicines such as tirzepatide.
Is Orforglipron the Same as Retatrutide?
No. Foundayo, the brand name of orforglipron, is not retatrutide. Both come from the same developer and both are used or studied for weight loss, but they are different molecules with different targets. Orforglipron acts only on the GLP-1 receptor, like semaglutide. Retatrutide also acts on the GIP receptor, like tirzepatide, and on the glucagon receptor. Orforglipron is approved in the US; retatrutide is not approved anywhere.
What Is Still Unknown
- How the two compare in a head-to-head trial; none has been reported.
- Retatrutide's long-term safety and whether it will be approved. Lilly plans to submit it to the FDA in the first quarter of 2027.
- What retatrutide will cost. It has no price because it is not approved; orforglipron's self-pay prices are covered in how much retatrutide may cost.
- Whether either medicine reduces heart attacks and strokes; retatrutide is being studied in TRIUMPH-Outcomes.
Sources
- Jastreboff AM, Kaplan LM, Davies MJ, et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity. N Engl J Med. Published September 29, 2026. DOI: 10.1056/NEJMoa2604169. (TRIUMPH-1)
- Eli Lilly. US prescribing information for orforglipron tablets (Foundayo). 2026. (ATTAIN-1, ATTAIN-2, adverse reactions, boxed warning)
- U.S. Food and Drug Administration. FDA approves first new molecular entity under National Priority Voucher program. April 1, 2026. (orforglipron)
- Eli Lilly. Lilly's triple agonist, retatrutide, delivered substantial weight loss and A1C reduction, underscoring its potential promise for people with obesity and type 2 diabetes. September 29, 2026. (TRIUMPH-2)
- Eli Lilly. Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials, delivering significant improvements in weight and A1C. July 23, 2026.
Medical Disclaimer: This article compares published trial results for general information only and is not medical advice. Retatrutide is investigational and is not approved by the FDA for any use. It is not available by prescription, and products sold online under its name are not sold or supplied by Lilly. Orforglipron is a prescription medication. Nothing here is a recommendation to use, choose between, seek out or avoid any medication.
Frequently asked questions
In their separate Phase 3 trials, retatrutide did. Counting everyone randomized, retatrutide 12 mg reduced weight by 25.0% over 80 weeks in TRIUMPH-1, and orforglipron 17.2 mg by 11.1% over 72 weeks in ATTAIN-1. The two have not been compared head to head, and the trials differed.
No. Orforglipron, sold as Foundayo, is a once-daily pill that acts only on the GLP-1 receptor and was approved by the FDA on April 1, 2026. Retatrutide is a different, investigational weekly injection that acts on GIP, GLP-1 and glucagon receptors and is not approved. Both come from the same developer.
Yes. The FDA approved orforglipron on April 1, 2026, for adults with obesity, or with overweight and at least one weight-related condition, together with a reduced-calorie diet and more physical activity, to reduce excess body weight and maintain weight reduction long term. Retatrutide is not approved for any use.
Both mainly cause nausea, vomiting, diarrhea and constipation, generally more often at higher doses. At the highest doses, nausea was reported by 42.4% on retatrutide and 35% on orforglipron. Retatrutide's trials also reported dysesthesia, an abnormal skin sensation. Separate trials cannot show reliably which causes side effects more often.
