Retatrutide Dosing Schedule: Complete Week-by-Week Titration Plan
Retatrutide remains an investigational once-weekly triple agonist, not an FDA-approved medicine. The Phase 2 obesity study used separate 1, 4, 8 and 12 mg target groups, while the dated Phase 3 TRIUMPH-1 report used 4, 9 and 12 mg targets. This guide keeps those study procedures and results separate; see Lilly's current status summary.
Retatrutide Trial Procedures and Target Groups
The Phase 2 publication reported assigned target groups rather than one universal 1→4→8→12 mg protocol. Its initial doses varied by target: 1 mg for the 1 mg target, 2 or 4 mg for the 4 and 8 mg targets, and 2 mg for the 12 mg target. The 2 mg step therefore has no standalone target-group outcome in that trial.
The dated May 21, 2026 Lilly TRIUMPH-1 report described a different procedure: all assigned 4, 9 and 12 mg target groups started at 2 mg, then used 2, 4, 6, 9 and 12 mg steps every four weeks only as needed to reach the assigned target. A target being reached ended escalation for that group; it did not mean study treatment stopped.
The Four Calendar Sections
- Weeks 1–4: the reported TRIUMPH-1 procedure used 2 mg for the 4, 9 and 12 mg target groups.
- Weeks 5–8: the procedure used 4 mg; the 4 mg group reached its assigned target in week 5 while higher assigned targets continued.
- Weeks 9–12: the 6 mg step was used only for the 9 and 12 mg target groups; the 4 mg group remained at its assigned target.
- Week 13 onward: the 9 mg group reached its assigned target in week 13, and the 12 mg group reached 12 mg only in week 17; assigned treatment continued at each target.
Week-by-Week Dosing Schedule Breakdown
The four tables below show the reported TRIUMPH-1 calendar as study context, not as a treatment plan. They use the study's once-weekly timing and identify which assigned targets needed each step. The Phase 2 publication does not establish these intermediate steps for every target group.
TRIUMPH-1 Weeks 1–4: Reported 2 mg Starting Step
| Weeks | Study timing | Reported amount | Assigned-target context |
|---|---|---|---|
| 1–4 | Once weekly under study procedures | 2 mg | Reported initial step for the 4, 9 and 12 mg target groups |
TRIUMPH-1 Weeks 5–8: Reported 4 mg Step
| Weeks | Study timing | Reported amount | Assigned-target context |
|---|---|---|---|
| 5–8 | Once weekly under study procedures | 4 mg | The 4 mg target is reached in week 5; 9 and 12 mg target groups continue to their assigned higher steps |
TRIUMPH-1 Weeks 9–12: Reported 6 mg Step
| Weeks | Study timing | Reported amount | Assigned-target context |
|---|---|---|---|
| 9–12 | Once weekly under study procedures | 6 mg | Used for the 9 and 12 mg target groups; the 4 mg group remains at its assigned target and continues treatment |
TRIUMPH-1 Week 13+: Assigned Targets Continue
| Weeks | Study timing | Reported amount | Assigned-target context |
|---|---|---|---|
| 13–16 | Once weekly under study procedures | 9 mg | The 9 mg target is reached in week 13; the 12 mg target continues to its next assigned step |
| 17+ | Once weekly under study procedures | 12 mg for the 12 mg target | The 12 mg target is reached in week 17; 4 and 9 mg target groups remain on their assigned targets and continue study treatment |
What to Expect at Each Dose Level
Trial observations are useful for understanding what researchers measured, but they do not predict an individual's symptoms, appetite, mood, energy or weight trajectory. The Phase 2 publication reported gastrointestinal events as generally mild or moderate and dose-related, with some mitigation when higher-target groups started at 2 mg rather than 4 mg. It did not establish a universal hour-, day- or week-specific adaptation pattern.
Phase 2 1 mg Target Group: Tolerability and Adaptation
The Phase 2 publication reported that the 1 mg target group started at 1 mg and had a mean 8.7% body-weight reduction at 48 weeks. It does not establish a universal symptom or appetite timeline at this amount.
Phase 2 4 mg Target Group: Appetite and Tolerability Observations
The Phase 2 4 mg target group had a mean 17.1% body-weight reduction at 48 weeks. Gastrointestinal adverse events were generally mild or moderate in the reported study and related to dose; the starting-dose comparison supports discussing, rather than promising, tolerability differences.
Phase 2 8 mg Target Group: Reported 48-Week Outcome
The Phase 2 8 mg target group had a mean 22.8% body-weight reduction at 48 weeks. The result is not evidence that 8 mg is universally optimal. The Phase 2 target group started at 2 or 4 mg, so it should not be recast as a mandatory week 9 step for every participant.
Phase 2 12 mg Target Group: Reported Efficacy and Limits
The Phase 2 publication reported a mean 24.2% body-weight reduction at 48 weeks for the 12 mg target group. The dated TRIUMPH-1 report separately described 28.3% at 12 mg after 80 weeks under its efficacy estimand and 25.0% under its treatment-regimen estimand. Those results do not establish that everyone should use the highest target or how effects behave after stopping.
When to Hold or Delay Your Dose Escalation
The reported schedules describe assigned study procedures, not a universal rule for changing an individual dose. If symptoms or other concerns arise, contact the responsible study team or prescribing clinician before making any change. This guide does not prescribe a hold, delay, restart or reduction interval.
Reasons to Discuss Escalation Timing
- New or worsening gastrointestinal symptoms: report symptoms promptly and ask what the assigned protocol permits.
- Difficulty maintaining usual hydration or nutrition: seek individualized guidance rather than applying a calorie threshold from an online schedule.
- Concerning pain, vomiting or a rapid heart rate: contact the clinical team promptly for triage; this page does not diagnose or set a restart plan.
- Any change in health, medicines or study eligibility: confirm whether the study team wants an assessment before the next assigned amount.
How to Request a Delay
Give the responsible study team or clinician the assigned target, actual product instructions, timing of symptoms and any other relevant medicines. Ask which options the protocol permits and when they want follow-up. Do not copy a different participant's calendar or use this article to choose a new amount.
Injection Day Timing and Consistency
The obesity trials used once-weekly subcutaneous administration under study procedures. The study descriptions do not create a universal clock time, weekday, injection-site rotation rule or preparation routine for an unapproved product. Participants should follow the supplied study or product instructions.
Best Practices for Injection Day
- Confirm the assigned amount: check the study record or product-specific instructions before administration.
- Use the actual supplied device and preparation directions: do not infer handling steps from a different medicine or vial.
- Record the administration and symptoms: share relevant information with the responsible clinical or study team.
- Ask before changing timing: a missed or delayed injection needs protocol- and product-specific instructions.
Treatment Beyond Target Attainment
In the reported TRIUMPH-1 procedure, reaching a target ended escalation for that assigned group, not treatment: the 4 mg group remained at 4 mg from week 5, the 9 mg group remained at 9 mg from week 13, and the 12 mg group reached 12 mg in week 17. The Phase 2 and TRIUMPH-1 reports describe their own follow-up periods; they do not establish a personal long-term maintenance schedule.
For more detailed information on retatrutide dosing mechanics, see our guide on retatrutide dosage calculations. For expectations on weight loss outcomes, review retatrutide before and after results. If considering alternatives, compare with retatrutide versus tirzepatide or retatrutide versus semaglutide.
Frequently Asked Questions
There is no single standard starting dose established by the studies summarized here. In the Phase 2 obesity study, the 1 mg target group started at 1 mg, the 4 and 8 mg target groups started at 2 or 4 mg, and the 12 mg target group started at 2 mg. In the reported TRIUMPH-1 procedure, all assigned 4, 9 and 12 mg target groups began at 2 mg. These are study procedures, not instructions for personal use.
The Phase 2 publication does not establish a universal 1 mg-to-4 mg calendar. In the reported TRIUMPH-1 procedure, participants assigned to the 4 mg target received 2 mg during weeks 1–4 and 4 mg from week 5; participants assigned to the 9 or 12 mg targets also followed the next steps only as needed for their assigned target. That study calendar should not be turned into a personal schedule.
The Phase 2 4 mg target group had a mean 17.1% body-weight reduction at 48 weeks, but that group result is not an individual prediction. Gastrointestinal adverse events in the publication were generally mild or moderate and dose-related; starting some higher-target groups at 2 mg rather than 4 mg partly mitigated those events. The study does not support a universal symptom timeline or a claim that a particular person will tolerate 4 mg.
Do not create a new interval or dose from this page. Ask the responsible study team or prescribing clinician what the assigned protocol permits, which symptoms require prompt contact, and whether any modification is allowed. The published trial summaries do not establish a universal hold, restart or slower-escalation schedule for personal use.
Twelve mg was the highest target in the Phase 2 and reported TRIUMPH-1 obesity programs summarized here. It is a studied target, not an FDA-approved prescribing dose or a recommendation that everyone reach it. The current Lilly status summary describes retatrutide as investigational.
The available results are study-group averages at defined time points, not a personal week-by-week forecast. Phase 2 reported mean reductions at 48 weeks for its 1, 4, 8 and 12 mg target groups; Lilly’s dated TRIUMPH-1 report described separate 4, 9 and 12 mg results at 80 weeks. The responsible clinical or study team should interpret response for an individual.
Do not pause, stop, taper, restart or switch based on this article. Contact the responsible study team or prescribing clinician for instructions tied to the actual protocol, product and symptoms. The cited trials do not establish a universal pause, restart, taper or abrupt-stop safety rule for retatrutide.