The filing timeline
In its second-quarter results on August 5, Lilly said retatrutide’s “clinical data package is now complete to support global registrations for obesity, obstructive sleep apnea, and knee osteoarthritis pain,” with “plans to submit a Biologics License Application to the U.S. FDA in the first quarter of 2027.”[1] With no application filed this year, retatrutide will not be available by prescription in 2026. Retatrutide remains investigational, and products sold online as “retatrutide” are not approved drugs.
The expanded access program
Lilly registered a “Pre-approval Expanded Access of Retatrutide (LY3437943)” program on ClinicalTrials.gov (NCT07629401), first posted June 5 and listed as available.[2] It is single-patient access, and the bar is high. It is for adults with:[2]
- a BMI of 35 or more;
- at least two serious or life-threatening obesity-related complications;
- obesity that is refractory to the best approved therapy; and
- no ability to join an ongoing retatrutide trial or a trial of a comparable investigational drug.
Requests have to come from the treating physician, through the Lilly Answers Center (1-800-545-5979). The listing says patients and caregivers should go to their doctor rather than contacting Lilly, and that availability “will depend on geography, product supply, and detailed individual eligibility assessment.”[2] In practice, someone who has not already tried and failed approved drugs such as Zepbound or Wegovy will not qualify.
What the phase 3 trials showed
TRIUMPH-1, published in the New England Journal of Medicine, randomized 2,339 adults with obesity but without diabetes for 80 weeks. Mean weight change was −17.6% on 4 mg, −23.7% on 9 mg and −25.0% on 12 mg, against −3.9% on placebo. In participants with knee osteoarthritis or sleep apnea, retatrutide also improved knee pain scores and the apnea-hypopnea index more than placebo. The most common side effects were gastrointestinal.[3]
TRIUMPH-2, in The Lancet, enrolled 1,152 adults with obesity and type 2 diabetes. At 80 weeks, weight fell 11.9%, 16.8% and 18.8% on the three doses, against 5.1% on placebo. Diarrhea affected about a quarter to a third of people on retatrutide.[4]
For how retatrutide compares with current drugs, see our TRIUMPH phase 3 review and the retatrutide approval and access timeline. For the risks of buying it before approval, see our review of retatrutide sold online.