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ReHuman trials

Retatrutide

A once-weekly triple agonist (GIP, GLP-1 and glucagon receptors). First phase 3 results are in; it is not approved anywhere yet. Sold in the Philippines only as a research peptide.

Investigational · not approved anywhereNot registered with the Philippine FDA
OverviewDosingMixingResearchCommunitySafetyFAQSources

Retatrutide quick reference

TypeGIP / GLP-1 / glucagon triple agonist
Studied forWeight, diabetes, liver fat, knee pain
EvidencePhase 3 in people; not approved
RouteWeekly subcutaneous injection
Half-lifeAbout 6 days

What is Retatrutide?

Once-weekly peptide that hits GIP, GLP-1 and glucagon receptors.

People use it for big weight loss; TRIUMPH-1 reached 28.3% at 80 weeks.

Still investigational; Lilly is running more phase 3 trials.

How Retatrutide works

GLP-1 receptor

Lowers appetite and slows stomach emptying.

GIP receptor

Adds to insulin release and appetite effects.

Glucagon receptor

Raised energy use in obese mice; human share is unclear.

Weekly exposure

Long half-life allows one injection a week.

What Retatrutide is studied for

PeopleWeight loss

Adults lost 28.3% on 12 mg at 80 weeks (TRIUMPH-1).

PeopleType 2 diabetes

HbA1c fell up to 2.0 points at 40 weeks.

PeopleFatty liver

Liver fat fell 82% on 12 mg in 24 weeks.

PeopleKnee osteoarthritis pain

Pain score fell up to 73% in a TRIUMPH-1 sub-trial.

PeopleSleep apnea

Apnea events fell up to 61% in a TRIUMPH-1 sub-trial.

AnimalsEnergy use

The glucagon part raised energy use in obese mice.

Retatrutide dosing protocol

WeeksWeekly amount in the trials (highest group)
1–42 mg
5–84 mg
9–126 mg (TRIUMPH-1) · 8 mg (phase 2)
13–169 mg (TRIUMPH-1) · 12 mg (phase 2)
17+12 mg (TRIUMPH-1 top group)

Phase 2 (NCT04881760) groups: 1, 4, 8 or 12 mg; the 12 mg group stepped 2, 4, 8, 12 mg. TRIUMPH-1 (NCT05929066): 2, 4, 6, 9, then 12 mg; the 4 mg group needed one step at 2 mg (Lilly, June 2026).

TRIAL SCHEDULE2 mg weekly, step up every 4 weeksTrial
TRIAL TARGETS4, 9 or 12 mg weeklyTrial
TIMINGSame day each weekTrial
COMMUNITY START0.5 mg weeklyCommunity
COMMUNITY STEPS1, 2, then 4 mg; 4+ weeks eachCommunity
COMMUNITY HOLDAbout 1 mg weekly once at goalCommunity

Label and trial amounts come from the sources below. Community amounts are what people report; they have not been tested.

Mixing

Vial10 mg
+
BAC water2 mL
=
Strength5 mg per mL

Community practice only. Swirl gently, never shake; store at 2–8 °C.

Open the peptide calculator

What the research found

Average body-weight change in the two main obesity trials:

−24.2%12 mg · 48 wks (phase 2)
−19.0%4 mg · 80 wks (TRIUMPH-1)
−25.9%9 mg · 80 wks (TRIUMPH-1)
−28.3%12 mg · 80 wks (TRIUMPH-1)

Placebo: −2.1% (phase 2, 48 weeks, 338 adults; Jastreboff et al., NEJM 2023) and −2.2% (TRIUMPH-1, 80 weeks, 2,339 adults; Lilly topline, May 21, 2026).

Retatrutide community experience

What users report. Not tested in trials.

Positive reports

  • Less food noise Many report fewer cravings and food thoughts.
  • Stronger appetite drop Some say it works harder than tirzepatide did.
  • Steady through the week Some feel even appetite control between injections.

Negative & mixed

  • Stomach trouble Nausea, diarrhoea and reflux often flare after a step-up.
  • Eating too little Strong appetite loss makes protein and fluids hard to hit.
  • Odd skin feelings Tingling or burning skin matches the trial dysesthesia signal.

Retatrutide stacking

Retatrutide + cagrilintide

Adds an amylin pathway. Not studied together; side effects may stack.

Retatrutide + protein and lifting

Common advice to protect muscle. Not tested with this drug.

Retatrutide + tesamorelin

Discussed for belly fat. Not studied together.

Retatrutide side effects & safety

Common

  • Nausea: 29–42% on retatrutide vs 15% on placebo (TRIUMPH-1).
  • Diarrhoea: 25–34% vs 14%.
  • Constipation: 24–26% vs 11%.
  • Vomiting: 11–25% vs 5%.
  • Worse at higher doses and during step-ups.

Less common

  • Dysesthesia (odd skin feelings): 5–13% vs 1%.
  • Urinary tract infection: 7–9% vs 5%.
  • Heart rate rose with dose in phase 2, then eased.
  • Stopped for side effects: 4% (4 mg) to 11% (12 mg).

Precautions

  • Investigational: long-term safety is not known.
  • Trials excluded people with past pancreatitis, MTC or MEN2.
  • Persistent vomiting or severe stomach pain needs medical care.
  • Do not stack with other GLP-1 drugs; side effects add up.

Our verdict on Retatrutide

Biggest weight loss seen in trials so far. Still unapproved, with skin sensations and long-term safety open.

Retatrutide FAQ

Is retatrutide approved?

No. It is investigational; Lilly is running phase 3 trials.

How much weight did people lose?

TRIUMPH-1: 19.0% (4 mg), 25.9% (9 mg), 28.3% (12 mg) at 80 weeks. Placebo: 2.2%.

How is it different from tirzepatide?

It adds glucagon receptor activity. A head-to-head trial (NCT06662383) is still running.

What is dysesthesia?

Odd skin feelings like tingling or burning. Seen in 5–13% in TRIUMPH-1.

Sources

  • ClinicalTrials.gov NCT04881760 (phase 2 dose groups)
  • ClinicalTrials.gov NCT05929066 (TRIUMPH-1)
  • Jastreboff AM et al. N Engl J Med 2023 (phase 2 results)
  • Eli Lilly TRIUMPH-1 topline release, May 21, 2026
  • Eli Lilly release, June 6, 2026 (TRIUMPH-1 detail, TRANSCEND-T2D-1, knee pain and sleep apnea sub-trials)
  • Coskun T et al. Cell Metab 2022;34:1234 (receptor activity, obese mice)
  • Urva S et al. Lancet 2022;400:1869 (phase 1b, NCT04143802)
  • Sanyal AJ et al. Nat Med 2024;30:2037 (liver fat substudy)
  • Rosenstock J et al. Lancet 2023;402:529 (phase 2 diabetes, NCT04867785)
  • TRANSCEND-T2D-1 report, Lancet 2026;407:2402 (NCT06354660)
  • ClinicalTrials.gov NCT05929066 (TRIUMPH-1 exclusion criteria)
  • ClinicalTrials.gov NCT06662383 (retatrutide vs tirzepatide, ongoing)