Retatrutide (5mg)

Retatrutide binds three metabolic receptors at the same time: GLP-1, GIP, and glucagon.^[1] In trial and laboratory work, that combination is studied for insulin secretion, gastric emptying, hepatic fat oxidation, and energy expenditure.

The peptide is built around a GLP-1 backbone, the same peptide scaffold behind semaglutide and tirzepatide, modified so it also binds and activates the GIP receptor and the glucagon receptor.^[1] GLP-1 slows gastric emptying and drives glucose-dependent insulin release. GIP improves insulin sensitivity and fat-cell signaling. Glucagon pushes the liver toward fat oxidation and raises resting energy expenditure.

That third receptor, glucagon, is what separates retatrutide from GLP-1/GIP dual agonists like tirzepatide. Activating glucagon receptors alone tends to raise blood glucose, so the molecule has to lean on its GLP-1 and GIP activity to keep glycemic control intact while still getting the metabolic-rate boost that glucagon signaling provides.^[1] A 2023 Phase 2 trial reported an 86% reduction in liver fat content at the highest dose, a magnitude larger than what's typically reported for GLP-1-only or dual-agonist compounds, and mechanistically consistent with the added glucagon-receptor activity.^[2]

Labs studying triple-agonist pharmacology typically run retatrutide alongside a single-receptor GLP-1 comparator and a dual-agonist comparator such as tirzepatide, since isolating which effect comes from which receptor is most of the analytical work in this compound class.

Retatrutide and tirzepatide share the same GLP-1/GIP foundation. Retatrutide adds a third receptor, glucagon, on top of it. No published trial has tested the two head-to-head. What exists is cross-trial comparison: in retatrutide's Phase 3 TRIUMPH-1 trial, the 12 mg dose produced 28.3% mean weight loss at 80 weeks;^[3] tirzepatide's Phase 3 SURMOUNT-1 trial reported roughly 22.5% at 72 weeks in its highest-dose arm. Different trials, different populations, different durations, so that gap is suggestive, not conclusive.

Tirzepatide has the regulatory head start. It's FDA-approved under the brand names Mounjaro and Zepbound. Retatrutide has none of that: it remains investigational, still moving through Lilly's Phase 3 TRIUMPH program, with no marketing application publicly accepted as of this writing. A 2025 NEJM trial, SURMOUNT-5, did run tirzepatide against semaglutide head-to-head and found tirzepatide's weight-loss effect larger,^[4] which is the closest published data gets to ranking this drug class, and it still doesn't include retatrutide.

Semaglutide, sold under the brand names Ozempic and Wegovy, activates GLP-1 only. Retatrutide activates GLP-1, GIP, and glucagon. On paper that's a wider mechanism, and the trial numbers line up with that: semaglutide's Phase 3 STEP program topped out around 14.9% weight loss at 68 weeks, versus retatrutide's 28.3% at 80 weeks in TRIUMPH-1.^[3] Again, these are separate trials run years apart on different populations, not a controlled comparison in the same patients.

Semaglutide has the longer track record. It carries FDA approval, a cardiovascular-outcomes label from the SELECT trial, and years of real-world prescribing data behind it. Retatrutide has none of that yet. It's a data-rich investigational molecule, not an interchangeable substitute, and this page does not present it as one.

The Phase 2 trial that put retatrutide on the map, published in the New England Journal of Medicine in 2023, reported up to 24.2% weight loss at 48 weeks on the 12 mg dose, alongside the liver-fat and glycemic findings noted above.^[2] Lilly's Phase 3 TRIUMPH program has since reported two trials. TRIUMPH-1, the main obesity trial (n=2,339), found 80-week weight loss of 19.0%, 25.9%, and 28.3% across the 4 mg, 9 mg, and 12 mg arms, versus 2.2% on placebo; a prespecified extension in participants with baseline BMI ≥35 reached 30.3% at 104 weeks on the 12 mg dose.^[3] TRIUMPH-4, in adults with obesity and knee osteoarthritis, reported 28.7% weight loss at 68 weeks alongside a 4.5-point reduction in WOMAC pain score.^[5]

On the safety side, discontinuation due to adverse events in TRIUMPH-1 was lower at the 4 mg dose than at higher doses, and gastrointestinal events, nausea, diarrhea, constipation, are the most consistently reported side effects across every retatrutide trial published so far, matching the pattern seen with other incretin-receptor agonists.^[2][3] None of the published trials describe an at-home or self-administered dosing schedule for lay use. The dose-escalation schema used in TRIUMPH-1 started participants at a low dose and stepped up on a fixed schedule under clinical-trial supervision, which is a controlled research protocol, not a set of instructions for individual use.^[3]

Two more TRIUMPH trials, in type 2 diabetes and obstructive sleep apnea, have also reported topline results, and additional readouts are expected through 2026 as Lilly's Phase 3 program completes.^[6]

There is no FDA safety determination for retatrutide, because there is no FDA approval. The numbers that exist come from supervised clinical trials, not from informal use of research reagents.

In the 2023 Phase 2 NEJM trial, gastrointestinal events were the most common: nausea, diarrhea, vomiting, and constipation. Most of those events were mild to moderate, most of them happened during dose escalation, and they were the usual reason participants discontinued.^[2] Heart rate rose in a dose-dependent way, peaked around week 24, then declined.^[2]

Headache appeared in the trial supplement's less-common events table (Table S10), not in the paper's main safety table. Incidence was 0% on placebo, 11.4% in one 8 mg arm, 6.5% in the 12 mg arm, and 3.3% of all participants.^[2] That table is not a safety claim about Tetrava's Research Use Only listing.

No. Retatrutide is not FDA-approved, has no brand name, and is not legally available as a prescription medication anywhere. In July 2026 Lilly said it plans to submit a Biologics License Application in the first quarter of 2027.^[8] A planned filing is not an approval, and no application has been publicly accepted by the FDA as of this writing.

The only sanctioned way to receive retatrutide as a treatment is enrollment in one of Lilly's TRIUMPH trials. ClinicalTrials.gov lists current status and eligibility under identifiers including NCT05929066 (TRIUMPH-1) and NCT05931367 (TRIUMPH-4).

"Where to buy retatrutide" and "where to get retatrutide" searches often mean a pharmacy or a gray-market vial for personal use. Tetrava Labs does not sell it for that. The listing on this page is a Research Use Only laboratory reagent for qualified lab procurement, not a consumer weight-loss product, and this page makes no treatment, dosing, or pricing claims tied to human use.

"Retatrutide price per month" and "retatrutide availability and cost" are questions built for a prescription drug with a pharmacy price and an insurance formulary. Retatrutide doesn't have either of those yet, since it isn't approved. The number that does exist is the catalog price for the RUO research reagent on this page, shown in the purchase panel above, priced per vial for laboratory use, not as a monthly treatment cost.

Unregulated online sellers marketing retatrutide with per-month pricing, dosing charts, or "starter kit" language are describing human use of an unapproved compound, not a laboratory reagent purchase. Evaluate any such listing the same way you'd evaluate an unverified supplement claim: does it publish a lot-specific Certificate of Analysis, or just a price and a promise?

Retatrutide has one of the more active peptide-research threads on Reddit, split roughly into two camps: people tracking the TRIUMPH trial readouts and cross-posting Lilly's press releases, and people discussing personal sourcing, pricing, and vendor comparisons for unregulated retatrutide products. The second category sits well outside what this page covers or endorses.

"Retatrutide dosing reddit" and "retatrutide side effects reddit" threads mix real trial data with unverified self-reports. A number quoted on Reddit is only as good as its source. If a thread states a weight-loss percentage or a side-effect rate as fact, check whether it traces back to a named TRIUMPH trial (like the ones cited above) or to an anonymous forum post. Long-term-effects claims are especially prone to this: no published trial has followed retatrutide participants long enough to make a durable long-term-safety claim, TRIUMPH-1's longest reported window is 104 weeks, so any "long term effects" thread claiming otherwise is extrapolating past the data.

Retatrutide's popularity has pulled in a wide range of online sellers, some legitimate research suppliers, some marketing an unapproved compound for human use with no regulatory oversight. Before you treat any vendor, including Tetrava Labs, as a qualified research supplier, verify:

• Lot identity: does the listing give a batch/lot number that matches the Certificate of Analysis shipped with the vial, or is the PDF generic or reused?
• COA/HPLC traceability: is the COA from an independent third-party lab, reporting purity by area-under-curve HPLC rather than an in-house claim?
• Identity confirmation: does the COA or an accompanying mass-spec report confirm the compound's identity, not just a purity percentage?
• Framing: does the listing describe a laboratory reagent, or does it market dosing schedules, monthly pricing, and human-use instructions for an unapproved compound?
• Storage and chain of custody: was the product shipped and stored consistent with a lyophilized peptide, with cold-chain notes where they apply?
• If a vendor cannot produce a lot-specific COA on request for a currently listed batch, do not treat them as a qualified research supplier. Price and marketing copy do not fix that.

"How much bac water for 10mg retatrutide" is asking for a reconstitution recipe. This page does not publish one. Diluent volume is a laboratory protocol choice, written into the assay SOP, not a catalog constant attached to a 10 mg vial.

Tetrava Labs ships retatrutide as a lyophilized powder. Store sealed vials at -20°C, skip repeated freeze-thaw cycles, and reconstitute under sterile technique with a protocol-appropriate diluent right before use. Bacteriostatic water is listed separately as a research solvent. It is not paired to any retatrutide SKU at a fixed milliliter amount.

Once reconstituted, store working solutions per your laboratory SOP and log diluent lot, reconstitution date, concentration, and operator in your ELN, so preparation conditions stay auditable against the batch Certificate of Analysis.