Retatrutide vs Orforglipron (Foundayo): Weight Loss, Side Effects and Status

Orforglipron, sold as Foundayo, is the Lilly drug you can get now, and retatrutide is the one that lost more weight in its trials. In the largest trial of each, counting everyone randomized, retatrutide 12 mg averaged 25.0% of body weight over 80 weeks, while the top Foundayo dose averaged 11.1% over 72 weeks. That is orforglipron vs retatrutide in one line: a daily pill with a US approval against a weekly injection that has no approved version yet.

No trial has put the two against each other, so every number below comes from separate trials, labeled as such. We start with the side-by-side, then take weight, side effects, dosing and access one at a time.

Orforglipron vs retatrutide at a glance

The first row of numbers deserves a caveat. The label reports the ATTAIN trials in tablet strengths, while the trial itself used capsules: Lilly Medical Information says the 36 mg capsule is bioequivalent to the 17.2 mg tablet, with comparable exposure. The NEJM paper's 36 mg figure, 11.2% against 2.1%, sits one tenth of a point from the label's 11.1%.

How much weight do people lose on orforglipron?

In ATTAIN-1, 3,127 adults with obesity and no diabetes took orforglipron or placebo for 72 weeks. The NEJM paper reports, counting everyone randomized, losses of 7.5% (6 mg), 8.4% (12 mg) and 11.2% (36 mg) against 2.1% on placebo. If you only count people who stayed on treatment, Lilly's April 1 release gives 12.4% on the top dose against 0.9% on placebo.

Now put those beside retatrutide on the same two yardsticks. In TRIUMPH-1, 2,339 adults without diabetes took retatrutide for 80 weeks. Counting everyone randomized, the NEJM paper gives 17.6% (4 mg), 23.7% (9 mg) and 25.0% (12 mg) against 3.9% on placebo. For people who stayed on treatment, Lilly's release gives 28.3% on 12 mg against 2.2%.

Subtract placebo and the gap holds. Retatrutide 12 mg beat placebo by 21.0 points in the NEJM paper, and Foundayo 17.2 mg beat it by 9.0 points in the label. On the stay-on-treatment yardstick it is 28.3 against 12.4.

In type 2 diabetes, where everyone loses less, the order stays the same. The Foundayo label gives 9.6% against 2.5% on placebo at 72 weeks in ATTAIN-2, which enrolled 1,613 adults. TRIUMPH-2, with 1,152 adults, gave 18.8% on retatrutide 12 mg against 5.1% on placebo at 80 weeks, 13.8 points better than placebo in The Lancet paper.

Our read: retatrutide's lead is large enough that the usual caveats, eight more weeks of treatment and slightly different people, are unlikely to erase it. Even so, "more weight lost" is not the same as "better for you". Ask whether you need that much, and whether you can get it.

For retatrutide's full numbers by dose and trial, see retatrutide weight loss results. For the other approved option from Lilly, see retatrutide vs tirzepatide.

Side effects and stopping rates

Both drugs cause the stomach effects you would expect from a GLP-1 drug, and both are worst while the dose goes up. The label's pooled table for Foundayo 17.2 mg against placebo, from the two trials the label reports, runs: nausea 35% vs 10%, diarrhea 25% vs 11%, vomiting 24% vs 4% and constipation 24% vs 9%. In TRIUMPH-1, retatrutide 12 mg against placebo ran: nausea 42.4% vs 14.8%, diarrhea 32.0% vs 13.5%, vomiting 25.3% vs 4.8% and constipation 26.1% vs 10.9%.

Retatrutide runs 7 points higher on both nausea and diarrhea (our subtraction), and vomiting and constipation are close. Two cautions apply. The Foundayo table pools a trial in people with diabetes with one in people without, while the retatrutide numbers come from a no-diabetes trial alone.

Stopping rates tell a similar story. On Foundayo, 8% of people overall stopped for side effects against 3% on placebo, climbing from 6% on 5.5 mg to 9% on 9 mg and 10% on 17.2 mg (label). The ATTAIN-1 paper gives 5.3% to 10.3% across doses against 2.7%. In TRIUMPH-1, 4.1%, 6.9% and 11.3% of people on 4, 9 and 12 mg stopped, against 4.9% on placebo. In TRIUMPH-2, which enrolled people with diabetes, the 12 mg figure was 7.7%.

Each drug also has side effects the other has less data on, so the lists differ. Retatrutide caused a burning or oversensitive skin feeling (dysesthesia) in 12.5% of people on 12 mg in TRIUMPH-1, against 0.9% on placebo. The Foundayo label reports a faster pulse, about 3 to 5 beats per minute higher at week 72 against 0.4 to 0.6 on placebo, and tachycardia in 3% against 0.9%. The Foundayo label also warns that it may make birth control pills less reliable, so people on them should use another method for 30 days after starting and after each dose increase.

Foundayo carries a boxed warning about thyroid C-cell tumors. The label says other GLP-1 drugs caused those tumors in animal tests, that orforglipron isn't active in the species used and so couldn't be tested the same way, and that the relevance to people hasn't been determined. Tirzepatide and semaglutide labels carry the same warning, and retatrutide has no label yet. If you have had medullary thyroid cancer or MEN 2, or a close relative has, the Foundayo label rules it out.

Dosing and daily life

Foundayo starts at 0.8 mg a day. After at least 30 days it goes to 2.5 mg, then at least 30 days later to 5.5 mg, and after at least 30 more days at each step a prescriber may move you to 9, 14.5 or 17.2 mg, the maximum. Miss 7 or more days in a row and the label says to restart at a lower dose. There is no fasting window, and you swallow the tablet whole.

Retatrutide in the trials was a weekly injection starting at 2 mg and rising every 4 weeks. The 12 mg arm in TRIUMPH-1 went 2, 4, 6, 9 and then 12 mg. That is a trial schedule, not a dosing recommendation, and no label exists yet.

The practical tradeoff is plain. The pill asks you to remember something every day and to pick it up from a pharmacy, while the shot asks you to inject once a week. If you want a pill, retatrutide isn't coming as one on any announced timeline. We cover that on oral retatrutide.

Which one can you actually get?

Foundayo, now. The FDA approved it for adults with obesity, or overweight with a weight-related condition, and Lilly's April 1, 2026 release said prescriptions were open through LillyDirect with shipping starting April 6. As of October 31, 2026, LillyDirect self-pay prices run from $149 for the 0.8 mg dose, $149 for 2.5 mg and $199 for 5.5 mg (the last two temporarily reduced through December 31, 2026), to $299 for 9 mg, and for 14.5 and 17.2 mg if refilled within 45 days. Lilly also lists a $50 a month price through the Medicare GLP-1 Bridge for eligible Part D members from July 1, 2026 to December 31, 2027, with prior authorization.

Retatrutide cannot be prescribed. Lilly last said, on September 29, 2026, that it plans to submit it to the FDA in the first quarter of 2027 as a Biologics License Application (BLA). On October 2, 2026, the FDA decided that retatrutide is a drug, not a biological product, so an application would need to be filed under section 505 of the Federal Food, Drug, and Cosmetic Act. Lilly's appeal on that question is pending in the Seventh Circuit, and we found no ruling as of October 31, 2026. Lilly has set no price, saying only that it will be "priced to reflect the overall value to the healthcare system". Our retatrutide release date page tracks the timeline.

Lilly says anyone selling retatrutide to consumers is breaking the law, so a vial for sale online isn't Lilly's product and isn't the same thing as the drug in these trials; our retatrutide for sale page explains what those listings are and what can go wrong. If you want what the trials describe, the legal routes are a clinical trial or, for a narrow group, Lilly's expanded access program.

Which Lilly drug to ask your doctor about

These are questions for a prescriber, not a verdict.

Do you want treatment now? Foundayo is the only one of the two that can be prescribed. Will a smaller loss do? Lilly's April 1 release puts the ATTAIN-1 average on the top dose at 25 pounds, and averages hide a wide spread between people. If you need much more, retatrutide's trial numbers are higher, but you can't act on them yet. Do you have a reason to avoid injections or daily pills? That narrows the choice before the numbers do.

Nobody has studied switching from one to the other, or using both. The Foundayo label says not to combine it with another GLP-1 receptor agonist, and retatrutide acts on that receptor too. For the rest of the pipeline, see new weight loss drugs, and for approved alternatives, the retatrutide alternatives hub.