Question 1

What is Retatrutide?

Accepted Answer

Retatrutide (LY3437943) is an investigational once-weekly injectable peptide developed by Eli Lilly. It is a triple agonist of the GLP-1, GIP and glucagon receptors — the first triple agonist to reach late-stage clinical trials for obesity and type 2 diabetes. It is administered subcutaneously and remains investigational as of 2026; it is not yet approved by the FDA for any indication.

Question 2

Is Retatrutide FDA approved?

Accepted Answer

No. As of 2026, Retatrutide is still in Phase 3 clinical trials and has not received FDA approval. Eli Lilly's lead Phase 3 obesity trial (TRIUMPH-1) is ongoing, with regulatory submission expected after Phase 3 readouts. Until approval, Retatrutide is only available through clinical trials or as a research-grade peptide from research chemical suppliers, not as a prescription medication.

Question 3

When will Retatrutide be released?

Accepted Answer

Eli Lilly has guided that Retatrutide could file for FDA approval after the TRIUMPH Phase 3 readouts complete (expected 2026–2027), which would put the earliest possible commercial launch around 2027 if approved on first review.

Question 4

Retatrutide vs Tirzepatide — what is the difference?

Accepted Answer

Tirzepatide (Mounjaro / Zepbound) is a dual GLP-1 + GIP agonist already approved by the FDA. Retatrutide adds a third receptor — glucagon — to the same dual-agonist mechanism, which in Phase 2 produced a mean ~24% body-weight reduction at 48 weeks at the highest dose. Retatrutide is investigational; tirzepatide is FDA-approved.

Question 5

How much weight loss did Retatrutide produce in trials?

Accepted Answer

In the Phase 2 obesity trial published in NEJM (2023), Retatrutide produced a mean body-weight reduction of 17.5% at 24 weeks and 24.2% at 48 weeks at the 12 mg once-weekly dose, compared with placebo. Phase 3 TRIUMPH-1 results have not yet been released.

Question 6

Where can I buy Retatrutide?

Accepted Answer

Retatrutide is not available by prescription because it has not been approved by the FDA. It is sold only as a research-grade peptide for laboratory use by research chemical suppliers (typically as 4 mg, 8 mg, 12 mg or 20 mg lyophilized vials at $99–$300+). RetatrutideCompare maintains side-by-side pricing, purity, shipping origin and certificate-of-analysis status across our full directory of verified suppliers.

Question 7

What are the side effects of Retatrutide?

Accepted Answer

The Phase 2 trial reported gastrointestinal side effects (nausea, vomiting, diarrhea, constipation) as the most common, mostly mild-to-moderate and concentrated in the titration phase, similar to other incretin agonists. Heart-rate increases were also reported at higher doses. Retatrutide is investigational and not approved for clinical use.

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