Retatrutide: Phase 3 Evidence and What Users Report
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What is retatrutide?
Retatrutide is an investigational once-weekly injection from Eli Lilly that activates three hormone receptors: GIP, GLP-1 and glucagon. It is being studied for obesity and related conditions, including in people with knee osteoarthritis. It is not approved by the FDA or Health Canada. As of 11 November 2026 this hub lists 397 published reports. Those accounts cannot be assumed to use the same product studied in trials. This is not a dosing recommendation.
What the trials show
TRIUMPH-4, announced by Lilly in December 2025 and later presented with more complete figures, was a 68-week phase 3 trial in 445 adults with obesity or overweight and knee osteoarthritis, without diabetes. Participants were randomised to investigational 9 mg or 12 mg weekly retatrutide or placebo, plus lifestyle counselling. Those trial arms are how the company reported results, not a dosing guide.
On the treatment-regimen estimand (the average result including people who stopped), mean weight change was -20.0% at 9 mg and -23.7% at 12 mg, versus -4.6% on placebo. On the efficacy estimand (if everyone had adhered), the averages were -26.4% and -28.7% versus -2.1%. Knee pain on the WOMAC pain subscale also improved more than placebo on both estimands. Adverse-event discontinuation was 12.9% at 9 mg and 18.2% at 12 mg, versus 4.0% on placebo. Earlier, a 48-week phase 2 trial reported about 24% average loss at the highest dose studied. Last reviewed: November 11, 2026.
Phase 2 also found dose-related heart-rate increases. Gastrointestinal effects were the most common reason people stopped in TRIUMPH-4. The 2026 WADA Prohibited List does not name retatrutide as an example; that is not itself permission for athletes, and unapproved pharmacological substances can fall under S0. Athletes should check the current list with their anti-doping organisation.
What retatrutide confessions describe
Heart rate is the most distinctive theme. Writers describe resting heart rate climbing and staying high (#42), a frightening night-time episode (#69), and sleep disrupted when it kicks in (#175, #129).
Others report large losses with metabolic changes (#58), odd skin sensations alongside nausea (#39), or switching from tirzepatide after a stall (#394). Because these products have not been reviewed as approved medicines, writers cannot know how they compare with the trial drug. These are anonymous accounts, not evidence.
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Anonymous retatrutide reports
If you have used retatrutide, including side effects or stopping, submit the account.
Submit yoursCommunity Q&A
- Is retatrutide FDA approved?
- No. It is in phase 3 trials and is not approved by the FDA or Health Canada.
- How much weight loss did retatrutide show?
- In TRIUMPH-4, treatment-regimen average loss at 68 weeks was 20.0% and 23.7% at the two doses reported, versus 4.6% on placebo. The efficacy estimand averages were 26.4% and 28.7% versus 2.1%. Those trial arms are not a dosing guide. Individual results vary.
- Does retatrutide raise heart rate?
- Phase 2 found dose-related heart-rate increases, and it is a common theme in user reports here. New palpitations or chest symptoms need urgent medical care.
- What is retatrutide skin burning (dysesthesia)?
- The earlier TRIUMPH-4 summary used on this site described burning or unusual skin sensations in 9% to 21% of participants versus about 1% on placebo, mostly mild to moderate. Later detailed presentations have focused more on gastrointestinal effects and discontinuations.
- How many retatrutide reports are on this site?
- As of 11 November 2026, this hub lists 397 published reports. The heading count updates as new reports are published.
- Does this page give dosing or sourcing advice?
- No. This is not a dosing recommendation. The site does not name or recommend suppliers.
- Is retatrutide safe?
- Its long-term safety is not established; it is still investigational. Phase 2 side effects were mainly gastrointestinal, with dose-related heart-rate increases and some skin-sensation changes.
- Is retatrutide a metabolism booster?
- It also activates the glucagon receptor, which is thought to increase energy expenditure, but most of its weight loss appears to come from reduced appetite. It is not approved.
Sources
Anonymous first-hand reports plus sourced context — educational only, not medical advice. Editorial policy & corrections.