Dual or triple agonist

Retatrutide

Retatrutide is investigational: it is still in clinical trials, and FDA has not approved it for any use. The evidence grade is moderate-human for weight loss and blood sugar in trials of up to 80 weeks. Pharmacies may not make it, and versions sold online are illegal.

investigationalchecked Evidence grade moderate-human · our assessmentVerified

This page has not been individually reviewed by a clinician.

Fact sheet · 5 facts

every row cites its source and its date
FactValueTierCheckedSource
Also calledLY3437943peer-reviewedpubmed.ncbi.nlm.nih.gov
Classdual-or-triple-agonistpeer-reviewedpubmed.ncbi.nlm.nih.gov
Regulatory statusinvestigationalprimaryfda.gov
Status source read2026-10-23primaryfda.gov
Evidence grademoderate-humanour assessmentpeptideindex.ai

Short answer

Retatrutide is investigational: it is still in clinical trials, and FDA has not approved it for any use. The evidence grade is moderate-human for weight loss and blood sugar in trials of up to 80 weeks. Pharmacies may not make it, and versions sold online are illegal.

Our assessment, drawn from the sources below.

What it is

Retatrutide is an experimental drug given as a weekly shot under the skin [9]. It acts on three hormones that help control blood sugar and body weight: GIP, GLP-1 and glucagon [10]. That is why researchers call it a triple-hormone agonist [9]. An agonist is a drug that switches on the same signal as a natural hormone.

Its lab code is LY3437943 [9]. Online sellers often call it Reta [16]. One drug company developed it and has paid for every large trial so far [9] [12] [13]. It is not sold in any pharmacy, and FDA has not approved it for any condition [1].

What the evidence shows

Evidence grade: moderate-human · our assessment

The evidence grade is moderate-human: trials in people show large weight loss and better blood sugar, but they are short and the maker paid for all of them [9] [12] [13]. A mid-stage trial of 338 adults with obesity ran for 48 weeks. People on the highest strength lost about 24% of their weight. People on a dummy shot lost about 2% [9]. A mid-stage trial of 281 adults with type 2 diabetes found lower HbA1c, a blood test of average blood sugar over about three months [10]. In a group of 98 people with fatty liver, liver fat fell by more than 80% on the higher strengths [11].

Two late-stage trials have now been published. In 537 adults with type 2 diabetes, HbA1c fell by about 1.7 to 1.9 points over 40 weeks, against 0.8 on a dummy shot. Weight fell by 11% to 15% [12]. In 1,152 adults with obesity and type 2 diabetes, weight fell by 12% to 19% over 80 weeks, against 5% on a dummy shot [13]. A 2025 review of four trials found it beat a dummy shot on every measure it pooled [14].

These trials tested the maker's own drug. They tell us nothing about products sold online, which may hold something else [16].

Known risks

  • In trials, the most common problems were nausea, diarrhea, vomiting and constipation. They were more common at higher strengths [9] [10].
  • In a mid-stage trial, heart rate went up more at higher strengths. It peaked at 24 weeks and then came down [9].
  • In an 80-week trial, low blood pressure and odd skin feelings, such as tingling or burning, happened more often than on a dummy shot [13].
  • In that trial, more people on the two higher strengths stopped the drug for good because of bad reactions or death than on a dummy shot [13].
  • One vial sold as retatrutide in a New York corner store held no peptide at all. Lab tests found a filler and live bacteria in it [16].
  • FDA warns that shots skip some of the body's defenses. Germs or toxins in an untested product can cause life-threatening illness [5].

What nobody knows yet

  • The longest published trial lasted 80 weeks. Nobody knows what years of use do to the body [13].
  • The published trials measured weight, blood sugar and liver fat. None has shown yet whether it prevents heart attacks, strokes or early death [12] [13].
  • The liver fat results come from 98 people in one trial. A much larger liver trial is still running [11] [7].
  • Nobody can tell what is in a product sold online. Two online samples matched a basic lab standard, but that standard is not the drug used in trials [16].
  • Nobody knows if FDA will approve it. Its maker plans to ask for approval in early 2027 [8] [15].

Legitimate ways to get it

The only legal way to get retatrutide in the US is to join a clinical trial [1] [7]. No approved product exists, and no pharmacy may lawfully make it [1] [3].

On 23 October 2026 the official trial registry listed two studies open to new people [7]. One is a large late-stage study of fatty liver disease with sites in many US states. The other is a smaller study with one site in China [7]. Each trial has strict rules on who may join.

Open trials are listed in the trials block below, with the date the official registry was last checked.

  • Clinical trial

    Retatrutide is only available inside clinical trials. Open trials are listed in the trials block below, with the date the official registry was last checked.

    clinicaltrials.gov

Recruiting trials

A listing is not a recommendation. Trials have strict eligibility rules. Talk to your doctor and read the official record.

Snapshot of .clinicaltrials.gov

  • NCT07467447

    Effect of LY3437943 Versus Placebo in Participants Who Have Obesity or Are Overweight

    Phase: Phase 2 · Sponsor: Hudson Biotech · Status: Recruiting

    Countries: China

    US states: none listed

    Official record for NCT07467447

  • NCT07165028

    Withheld under our publishing rules. Read it in the official record.

    Phase: Phase 3 · Sponsor: Eli Lilly and Company · Status: Recruiting

    Countries: United States, Argentina, Australia, Austria, Belgium, Brazil, Bulgaria, Canada, China, Czechia, France, Germany, Hong Kong, Hungary, India, Israel, Italy, Japan, Mexico, Netherlands, New Zealand, Norway, Poland, Portugal, Puerto Rico, Romania, South Korea, Spain, Sweden, Switzerland, Taiwan, Turkey (Türkiye), Ukraine, United Kingdom

    US states: Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Nevada, New Jersey, New Mexico, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Virginia, Washington, West Virginia

    Official record for NCT07165028

How people are getting it anyway

This section describes what happens and is not a recommendation.

Retatrutide reaches people outside trials in three main ways, and none of them is legal [1]. The first is online sellers that label it for research use. FDA sent warning letters to such sellers in December 2024, March 2026 and August 2026 [2] [5] [6]. In 2026, a news team also found it for sale in New York corner stores [16]. The second is businesses that offer it as a compounded drug. FDA warned two of them in September 2025 [3] [4]. The third is online health businesses that sell it after a short form. FDA says it has warned such companies [1]. A news team ordered it from two such sites, and at least one order arrived with no consultation [16].

In each case, nobody checks what is in the vial [1]. One vial a news team tested held no peptide, a filler and live bacteria [16]. In court, the maker says these products are more likely to hold contaminants [15]. It has sued six companies and reported more than 200 others to officials [8] [15].

  • Research use seller

    Sold online, and in some corner stores, in vials labeled for research use only or not for human use.

    The lawFDA treats these as unapproved new drugs when the seller's site shows they are meant for people, whatever the label says.fda.gov

    Documented riskA vial sold as retatrutide held no peptide. Lab tests found a filler and 13 colonies of bacteria.cbsnews.com

    Documented riskFDA warns that injected products skip some of the body's defenses, so toxins or germs in them can cause life-threatening illness.fda.gov

    Documented riskFDA says these products are of unknown quality and may harm health.fda.gov

    Enforcement FDA warning letter to an online seller of research-use peptides, including retatrutide.fda.gov

    Enforcement FDA warning letter to an online seller of research-use retatrutide.fda.gov

    Enforcement FDA warning letter to an online seller of research-use peptides, including retatrutide.fda.gov

  • Compounding outside the rules

    Versions offered as compounded drugs by online businesses and pharmacies, made from raw ingredient bought from distributors.

    The lawRetatrutide cannot be used in compounding under federal law. It is not part of any approved drug and is on no list of allowed raw ingredients.fda.gov

    Documented riskFDA does not check compounded drugs for safety, quality or whether they work before they are sold.fda.gov

    Documented riskOne business told buyers that compounded retatrutide was the active ingredient in approved weight-loss drugs. FDA said that claim was false.fda.gov

    Enforcement FDA warning letter to an online business offering compounded retatrutide.fda.gov

    Enforcement FDA warning letter to a second online business offering compounded retatrutide.fda.gov

  • Telehealth

    Online health businesses that sell it after a short online form, sometimes promising a review by a doctor or nurse.

    The lawFDA has warned telehealth companies for marketing unapproved drugs such as retatrutide, including directly to consumers.fda.gov

    Documented riskA news team ordered it from two such sites. At least one order arrived with no talk with a health worker.cbsnews.com

Sources

  1. [1]FDA: concerns with unapproved GLP-1 drugs used for weight loss, updated 1 October 2026Regulatory · primary
  2. [2]FDA warning letter to an online seller of research-use peptides, 10 December 2024Regulatory · primary
  3. [3]FDA warning letter on compounded retatrutide, 9 September 2025Regulatory · primary
  4. [4]FDA warning letter on compounded retatrutide, 9 September 2025, second businessRegulatory · primary
  5. [5]FDA warning letter to an online seller of research-use retatrutide, 31 March 2026Regulatory · primary
  6. [6]FDA warning letter to an online seller of research-use peptides, 24 August 2026Regulatory · primary
  7. [7]ClinicalTrials.gov: recruiting and not yet recruiting studies of retatrutideReference · primary
  8. [8]ArentFox Schiff: research-use labels are not a legal strategy, 18 September 2026Legal analysis · legal-analysis
  9. [9]Phase 2 trial of retatrutide in adults with obesity, 2023Rct · peer-reviewed
  10. [10]Phase 2 trial of retatrutide in adults with type 2 diabetes, 2023Rct · peer-reviewed
  11. [11]Phase 2a trial of retatrutide for fatty liver disease, 2024Rct · peer-reviewed
  12. [12]TRANSCEND-T2D-1: phase 3 trial of retatrutide in type 2 diabetes, 2026Rct · peer-reviewed
  13. [13]TRIUMPH-2: phase 3 trial of retatrutide in obesity with type 2 diabetes, 2026Rct · peer-reviewed
  14. [14]Review of trials of retatrutide for obesity, 2025Systematic review · peer-reviewed
  15. [15]CBS News: the maker sues sellers of its experimental weight-loss drug, August 2026Reference · established-news
  16. [16]CBS News: lab tests of products sold as retatrutide, October 2026Reference · established-news

Last verified · 5 facts · 7 sources

Primary source: https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss

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Information, not medical advice.

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