lookindex

Retatrutide

Also known as LY3437943, Reta, Triple agonist

Strong phase 3 weight loss data, no approval anywhere. Anything sold today is outside a trial, so those results say nothing about what is in the vial.

Information only. Not medical advice. Talk to a doctor before you start, stop or change anything.

What people claim

  • The strongest weight loss drug yet
  • Safe, because a major drug company tested it
  • "Research grade" is the same as the trial drug

What the evidence shows

  • In TRIUMPH-1, with 2,339 adults over 80 weeks, the top dose led to 25.0% weight loss against 3.9% on placebo when everyone was counted. The 28.3% headline figure only counts people who stayed on treatment.[1]
  • 11.3% of people on the top dose stopped because of side effects, against 4.9% on placebo.[1]
  • These results were first reported by the manufacturer. The long-term heart and kidney outcomes trial is not due to finish until 2029.[1][2]
  • Trial results apply to the trial drug. They do not apply to online products: TGA testing found less retatrutide than the label stated, with variation between samples.[3]

Known risks

  • Nausea, diarrhoea, constipation and vomiting were the most common side effects in trials.[1]
  • Dysesthesia (abnormal skin sensations) and urinary tract infections were more common than on placebo.[1]
  • Regulators say there is no guarantee products sold online contain retatrutide at all.[4][5]
  • FDA says the quality of "research use" products is unknown and they may be harmful.[6]
  • Long-term safety is still being studied.[2]

Reported side effects

Moderated user reports are not open yet, so nothing is shown here. They will be labelled as unverified personal accounts.

Legal status

A summary, not legal advice. Rules change, and sport bans are separate.

United States

Unapproved

Trials only. It cannot legally be used in compounding, and FDA has sent warning letters to sellers.[6]

United Kingdom

Unlicensed

MHRA says products sold outside trials are likely illegal and potentially dangerous.[5]

Australia

Not approved

TGA says it should not be used outside a clinical trial and any product sold could be counterfeit.[3]

European Union

Not authorised

Trials only.

Sources

  1. 1.Retatrutide confers up to 28.3% weight loss in obesityHealio, May 2026
  2. 2.TRIUMPH-Outcomes trial record (NCT06383390)ClinicalTrials.gov
  3. 3.TGA testing finds unapproved peptides do not contain what their labels claimTGA Australia, Nov 2026
  4. 4.TGA tests counterfeit retatrutide product after serious adverse event reportTGA Australia
  5. 5.No summer shortcut for safe weight lossMHRA UK, 2026
  6. 6.FDA's concerns with unapproved GLP-1 drugs used for weight lossUS FDA

Profile last checked 7 Nov 2026.