Claimed effect · Retatrutide

Does Retatrutide help with knee osteoarthritis pain?

B
Grade B — probable, not settled1 phase 3 RCT published (subgroup n=574); 1 phase 3 topline · effect size: moderate
Short answerProbable, not settled. Human data exist (1 phase 3 RCT published (subgroup n=574); 1 phase 3 topline) and mostly agree, showing a moderate effect — but too few, too small, or not yet peer-reviewed for a firm answer. TRIUMPH-1, now published, included 574 participants with knee osteoarthritis: WOMAC pain fell 3.9 points on 9 mg and 4.1 on 12 mg versus 2.5 on placebo, counting everyone randomised (differences −1.4 and −1.6; both P<0.001). TRIUMPH-4, still a press release, enrolled only adults with obesity and knee osteoarthritis: up to 4.5 points (75.8%) vs 2.4 (40.3%) on placebo. Weight loss likely explains much of it.

What the studies show

TRIUMPH-1, now published, included 574 participants with knee osteoarthritis: WOMAC pain fell 3.9 points on 9 mg and 4.1 on 12 mg versus 2.5 on placebo, counting everyone randomised (differences −1.4 and −1.6; both P<0.001). TRIUMPH-4, still a press release, enrolled only adults with obesity and knee osteoarthritis: up to 4.5 points (75.8%) vs 2.4 (40.3%) on placebo. Weight loss likely explains much of it.

“Among the participants with knee osteoarthritis, the corresponding changes in the pain score in the retatrutide groups for the hybrid estimand were -3.2, -3.5, and -3.6 versus -1.9 with placebo (differences, -1.6 and -1.8 points; both P<0.001); the corresponding changes for the ITT estimand were -3.4, -3.9, and -4.1 versus -2.5 with placebo (differences, -1.4 and -1.6 points; both P<0.001).”

Verbatim, from the abstractJastreboff AM, et al. Retatrutide, a triple hormone receptor agonist, for treatment of obesity (TRIUMPH-1). N Engl J Med, 2026 (online 29 Sep)

Human trials exist and mostly agree, but there are too few of them, they are too small, or one big one is still reading out. Expect the grade to move.

  1. 1
    Jastreboff AM, et al. Retatrutide, a triple hormone receptor agonist, for treatment of obesity (TRIUMPH-1).N Engl J Med, 2026 (online 29 Sep)2,339 randomised, 80 weeks; −25.0% on 12 mg vs −3.9% placebo by intention to treat. Subgroups with knee osteoarthritis (n=574) and obstructive sleep apnoea (n=243). NCT05929066.
  2. 2

In context

Retatrutide is an investigational once-weekly peptide that activates three receptors at once: GIP, GLP-1 and glucagon. In TRIUMPH-1, a 2,339-person phase 3 trial published in September 2026, adults with obesity lost 25.0% of body weight at 80 weeks on the top dose against 3.9% on placebo; in adults who also have type 2 diabetes the figure was 18.8% (TRIUMPH-2). A separate published trial cut HbA1c by up to 1.9 percentage points. It is not approved anywhere, and no legitimate supply exists outside clinical trials.

Retatrutide is investigational. Legal status differs by country — see the regulation section or the jurisdiction pages.

Questions

Is Retatrutide proven to help with knee osteoarthritis pain?
Not yet settled. 1 phase 3 RCT published (subgroup n=574); 1 phase 3 topline — LYO grades it B, meaning probable but liable to change as trials read out.
What studies are behind the grade?
TRIUMPH-1, now published, included 574 participants with knee osteoarthritis: WOMAC pain fell 3.9 points on 9 mg and 4.1 on 12 mg versus 2.5 on placebo, counting everyone randomised (differences −1.4 and −1.6; both P<0.001). TRIUMPH-4, still a press release, enrolled only adults with obesity and knee osteoarthritis: up to 4.5 points (75.8%) vs 2.4 (40.3%) on placebo. Weight loss likely explains much of it.
Is Retatrutide approved for this?
No. Retatrutide is investigational; it is not an approved medicine for any indication in the jurisdictions LYO covers.

Other outcomes for Retatrutide

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 →