Retatrutide remains investigational. These are trial arms, not prescribing instructions, and the starting dose materially affected tolerability. This is educational source context, not a protocol or recommendation.
How sourced amounts are organized
Lower trial arm1 mg / week48 weeks
A fixed lower-dose arm in the phase 2 obesity trial.
Mid trial arms4-8 mg / weekAfter 2 or 4 mg starts
Maintenance exposures tested after different starting strategies.
Highest phase 2 arm12 mg / weekAfter a 2 mg start
The highest maintenance arm; it is not an approved dose.
The in-app 2.5 mg preset is a recorded library row; it was not a maintenance arm in the cited phase 2 trial.
Patterns described in source material
Once weekly
All phase 2 obesity arms used weekly subcutaneous administration.
Escalated arms
The 4, 8, and 12 mg groups used defined starting-dose and escalation strategies.
Trial protocol only
Outside a trial there is no regulator-approved schedule.
Clinical context
1, 4, 8, or 12 mgOnce weeklyPhase 2 obesity trialNCT04881760
“Established” here means directly tested in humans, not approved.
Storage, handling and interpretation
Lyophilized material
Keep cold, dry, and protected from light according to the manufacturer certificate or validated lab SOP.
After reconstitution
Use sterile technique, refrigerate as validated, and avoid repeated freeze-thaw cycles.
Traceability
Record lot, concentration, preparation date, and the identity/purity documentation used by the lab.
Reported protocols for Retatrutide
What published studies and recent community write-ups report about amounts, timing and course length. 5 clinical and 4 community-reported rows, each linked to its source. These are descriptions of what others report, not instructions, and nothing here is medical advice.
Context
Dose
Frequency
Route
Course
Source
Clinical5 rows
Phase 2 obesity trial338 adults with obesity, or overweight plus a weight-related condition, without diabetes
1, 4, 8 or 12 mg maintenance (initial dose 2 or 4 mg)
Weight fell 8.7%, 17.1%, 22.8% and 24.2% at 48 weeks in the 1, 4, 8 and 12 mg groups versus 2.1% on placebo. Gastrointestinal events were dose-related and partly mitigated by starting at 2 mg rather than 4 mg, and heart rate rose dose-dependently, peaking at 24 weeks before declining.
Phase 2 type 2 diabetes trial281 adults with type 2 diabetes, HbA1c 7.0-10.5% and BMI 25-50
0.5, 4, 8 or 12 mg maintenance (escalated from 2 or 4 mg every 4 weeks)
HbA1c fell by about 2 percentage points and body weight by up to 16.9% at 36 weeks on 12 mg, measured against 1.5 mg dulaglutide and placebo comparators. Mild to moderate gastrointestinal events occurred in 35% of retatrutide participants and no severe hypoglycemia was reported.
Phase 3 TRIUMPH-4 (obesity with knee osteoarthritis)445 adults with obesity or overweight and knee osteoarthritis, without diabetes
Doses were raised every four weeks through 2, 4 and 6 mg (and 9 mg for the 12 mg arm). Topline weight loss was 26.4% at 9 mg and 28.7% at 12 mg, with WOMAC pain scores falling by up to 4.5 points; 84% of participants had a baseline BMI of 35 or more.
Phase 3 TRIUMPH-1 (obesity without diabetes)2,339 adults with obesity, or overweight with a comorbidity, without diabetes
4, 9 or 12 mg maintenance, starting at 2 mg
Once weekly
Subcutaneous
80 weeks, with a 24-week extension to 104 weeks for a subgroup with BMI of 35 or moreNone; up to two permanent dose reductions were allowed for side effects or excessive weight loss
Mean weight change at 80 weeks was 17.6%, 23.7% and 25.0% for 4, 9 and 12 mg versus 3.9% on placebo by intention to treat (19.0%, 25.9% and 28.3% by the efficacy estimand). Nausea, diarrhea, constipation and vomiting were the most common adverse events, and discontinuation for adverse events rose from 4.1% at 4 mg to 11.1% at 12 mg against 4.6% on placebo.
Phase 3 dose-escalation ladder (TRIUMPH program)Adults randomized to retatrutide in TRIUMPH-1
2 mg start, then 4, 6, 9 and 12 mg steps
Once weekly, stepping up every 4 weeks
Subcutaneous
4-16 weeks of escalation depending on target dose, then maintenanceNone; the extension escalated participants to a maximum tolerated dose of 9 or 12 mg
The sponsor describes a fixed ladder: 4 mg reached with a single step from 2 mg, 9 mg via 2, 4 and 6 mg, and 12 mg via 2, 4, 6 and 9 mg, each held for four weeks. Discontinuation for adverse events in the topline release was 4.1%, 6.9% and 11.3% for the 4, 9 and 12 mg arms versus 4.9% on placebo.
Community-reported4 rows
Slow community ramp
0.5 mg start, rising to 8 mg (some to 12 mg)
Once weekly, stepping up every 4 weeks
Subcutaneous
About 20 weeks of escalation, then open-ended maintenanceHold the current dose an extra 4 weeks if side effects appear rather than escalate
Community resource2026
This 2026 guide lays out 0.5, 1, 2, 4, 6 and then 8 mg, each held four weeks, with 8 mg described as the maintenance point for most and some continuing to 12 mg. It treats gastrointestinal tolerance as the limiting factor and says there is no advantage to reaching higher doses faster.
Conservative start for GI-sensitive users
0.5 mg for 2 weeks, 1 mg for 2 weeks, then 2, 4 and 6 mg
Once weekly, 4 weeks per step from 2 mg onward
Subcutaneous (abdomen, thigh or upper arm, rotating)
16 weeks to reach 6 mgTaper over 4-6 weeks when stopping (half dose for 2 weeks, then a quarter)
Community resource2026
Positions a 0.5-1 mg start below the 2 mg trial starting dose to reduce early nausea, at the cost of a 2-4 week delay in appetite effects. It also lists hold rules (gut symptoms above 3 of 10 for more than 3 days, resting heart rate up more than 15 bpm) and a tapered exit.
About 12, 16 or 32 weeks to reach 12 mg12 mg described as the ceiling; no published trial has exceeded it
Community resource2026
A nutrition site's 2026 chart sets the phase 2 ladder, the TRIUMPH ladder and a slower community ramp side by side and ties the choice of starting dose to prior GLP-1 experience. It flags that 15 mg has never been tested and that no missed-dose rule has been published for retatrutide.
16 weeks of escalation, then maintenance at 4, 9 or 12 mgNone described; missed-dose handling borrowed from tirzepatide labeling
Community resource2026
Ro summarizes the phase 3 ladder and stresses that no FDA-approved schedule exists, that 6 mg was only an escalation step, and that some trial participants had doses reduced after losing enough weight. It describes retatrutide as unavailable outside clinical trials.
How a course is commonly described
1
Weeks 1-4: 2 mgClinical
Every TRIUMPH trial started at 2 mg once weekly and held it for four weeks. Community guides aimed at first-time users describe starting at 0.5-1 mg instead, and gastrointestinal effects cluster in this escalation period in both settings.
2
Weeks 5-8: 4 mgClinical
The first step up. In TRIUMPH-1 this was also the lowest maintenance dose, producing 17.6-19.0% weight loss at 80 weeks with the lowest rate of discontinuation for adverse events among the retatrutide arms.
3
Weeks 9-16: 6 mg, then 9 mgClinical
Intermediate steps toward the 9 and 12 mg maintenance doses, each held four weeks. 6 mg was an escalation step only and was never studied as a maintenance dose.
4
Week 17 onward: maintenanceClinical
Maintenance at 4, 9 or 12 mg ran to week 68 in TRIUMPH-4 and week 80 in TRIUMPH-1, with weight still falling through week 104 in the extension. Up to two permanent dose reductions were permitted, most often for perceived excessive weight loss or a BMI of 22 or less.
5
Slow community rampCommunity-reported
Community charts stretch the ladder to 0.5, 1, 2, 4, 6 and 8 mg (sometimes on to 12 mg) with four weeks per step, taking 20-32 weeks to reach the top and holding a dose longer whenever side effects appear.
6
StoppingCommunity-reported
No trial describes a break or taper. One community guide describes tapering over 4-6 weeks when stopping, citing weight regain after discontinuation of this drug class, and another notes that no missed-dose rule has been published.
Retatrutide has no approved label, so even the TRIUMPH ladder is a trial protocol rather than a dosing recommendation. 12 mg once weekly is the highest dose any published trial has used.
Community ramps that start at 0.5 mg have never been compared with the 2 mg trial start. The phase 2 trial only showed that starting at 2 mg was better tolerated than starting at 4 mg.
Trial participants received manufacturer-supplied drug under medical supervision, with scheduled dose reductions for excessive weight loss. Product sold online as retatrutide is unregulated and untested.
Plus 4 community resources (dosing guides, forum threads and vendor write-ups), reported above but not linked.
Overview
Retatrutide (LY3437943) is an investigational once-weekly injectable peptide that activates the GIP, GLP-1 and glucagon receptors at the same time. It is a 39-amino-acid analog with two Aib residues, an alpha-methyl-leucine, a C-terminal amide and a C20 fatty diacid attached through a linker to lysine 17, which extends its half-life to roughly a week. In phase 2 it produced a mean weight loss of 24.2% at 48 weeks, and the phase 3 TRIUMPH program has reported 25-28% at 80 weeks; it remains investigational, with no approved label or dosing schedule.
What researchers are exploring
These themes describe recurring questions in published research. They are not claims of effectiveness or recommendations for use.
1
Obesity trials
Phase 2 research tested 1, 4, 8, and 12 mg weekly maintenance groups.
2
Dose response
Weight and adverse-event outcomes varied by maintenance and starting dose.
3
Metabolic endpoints
Programs examine glycaemia, lipids, liver fat, and cardiometabolic markers.
4
Heart-rate signal
Dose-dependent heart-rate increases were reported and monitored in trials.
What the current evidence can support
Study models remain visible so laboratory and animal findings are not mistaken for established human outcomes.
Human
Randomized phase 2 obesity trial
The 48-week trial enrolled 338 adults and compared multiple weekly doses with placebo.
Human
Lower starting doses improved tolerability
Gastrointestinal events were common and were partially mitigated by starting at 2 mg rather than 4 mg.
Review
Still investigational
No approved retatrutide product or public prescribing schedule exists.
Amounts recorded for Retatrutide
These amount records are independent from vial strength, reconstitution volume and measuring device. A recorded source is not the same as study backing, and these values are not recommendations.
1
Lowest phase 2 armSign in for schedule, duration and source context.
1 mg
2
Phase 2 starting amountSign in for schedule, duration and source context.
2 mg
3
Conservative phase 2 target capSign in for schedule, duration and source context.
4 mg
Chemistry identifiers
Sequence, synonyms and registry identifiers as recorded in PubChem, the National Library of Medicine's open chemistry database. Formula, mass and CAS number are summarized at the top of the page.