Retatrutide Dosing: Trial Doses, What They Did, and Why Charts Disagree
By The RX Index Editorial Team · Last verified October 2026
There is no FDA-approved retatrutide dosing schedule. In the five Phase 3 trials compared here, retatrutide groups started at 2 mg weekly, with planned four-week steps toward assigned targets of 4, 9, or 12 mg. TRIUMPH-1 estimated 19.0%, 25.9%, and 28.3% weight loss at 80 weeks assuming continued treatment.
That's a study plan, not a prescription. Three things change the answer: Lilly's stated filing plan is early 2027, it's still testing new ways to ramp up, and the documented ways to get Lilly's retatrutide are a trial or a narrow expanded-access program.
Here's the tradeoff behind the biggest number. In TRIUMPH-1's continued-treatment estimate, the 12 mg group lost just 2.4 percentage points more weight than the 9 mg group. But 11.3% stopped treatment after adverse events—health problems recorded during the study—at 12 mg, versus 6.9% at 9 mg. Those are differences between assigned groups, not the benefit of raising one person's dose. The results are below.
This page is for you if you want the real trial doses, you found two charts that don't match, or you're deciding whether to wait for retatrutide.
It's not for you if you want mixing, unit, or injection steps for a vial. We don't publish those for an unapproved drug, and we explain why below. Already took something and feel unwell? Jump to help.
Retatrutide dosing chart: the schedule used in five Phase 3 trials
In TRIUMPH-1, -2, -3, -4 and TRANSCEND-T2D-1, the planned retatrutide starting dose was 2 mg, injected under the skin once a week. The plan used four-week steps (2, 4, 6, 9, then 12 mg) up to each group's assigned target. The 6 mg dose was a step, not a target, in these trials.
| Planned trial weeks | 4 mg target group | 9 mg target group | 12 mg target group |
|---|---|---|---|
| 1–4 | 2 mg | 2 mg | 2 mg |
| 5–8 | 4 mg (target) | 4 mg | 4 mg |
| 9–12 | 4 mg | 6 mg | 6 mg |
| 13–16 | 4 mg | 9 mg (target) | 9 mg |
| 17 and after | 4 mg | 9 mg | 12 mg (target) |
Source: Lilly's published methods for TRIUMPH-1 (May 21, 2026), TRIUMPH-2 and TRIUMPH-3 (July 23, 2026), TRIUMPH-4 (December 11, 2025), and TRANSCEND-T2D-1 (March 19, 2026). TRIUMPH-3 and TRIUMPH-4 used only the 9 and 12 mg target groups. This is the planned research schedule; actual treatment could include interruptions or dose changes. It is not a dosing schedule for anyone to follow.
Think of the plan like a staircase with a landing every four weeks. The 4 mg group stopped on the first landing. The 12 mg group climbed all four flights.
A few plain definitions help here:
- mg means milligrams, the amount of the drug itself.
- Titration (also called escalation) means raising the dose in planned steps, so the body has time to adjust.
- Target dose (sometimes called the maintenance dose) is the dose a trial group was assigned to stay on. It is not a plan for keeping weight off after treatment.
Under these numbers is an important detail. On the planned schedule, the 4 mg group reached its target in week 5. The 9 mg group got there in week 13. The 12 mg group didn't reach 12 mg until week 17.
Why the starting dose matters: 2 mg versus 4 mg
In the earlier Phase 2 obesity trial, some groups started at 2 mg and others at 4 mg. The researchers reported that stomach side effects were partly reduced in the groups that started lower (NEJM, 2023). The five Phase 3 trials above used a 2 mg start.
The clearest example is the two 8 mg target groups: nausea was reported by 6 of 35 people (17%) starting at 2 mg, versus 21 of 35 (60%) starting at 4 mg. Those are small study groups, not a personal risk forecast (Table 3).
What does each number on a retatrutide chart mean?
The same number can mean different things in different studies. In the 2023 Phase 2 obesity trial, the target groups were 1, 4, 8, and 12 mg. Across the five Phase 3 trials above, the targets were 4, 9, and 12 mg, with 2 and 6 mg used only as steps on the way up.
This is why two honest charts can show different numbers. One might show a step. The other might show only the targets. Here's how common numbers fit these particular studies.
| Number on a chart | Phase 2 obesity trial (2023, 338 adults, 48 weeks) | Five Phase 3 trials compared here (2025–2026) |
|---|---|---|
| 0.25 mg | Not a starting or target dose | Not used in these regimens |
| 0.5 mg | Not in this obesity trial; studied in a separate diabetes trial | Not used in these regimens |
| 1 mg | Its own target group (the lowest in this obesity trial) | Not used in these regimens |
| 2 mg | Starting dose for some 4, 8, and 12 mg groups | Starting dose for all retatrutide groups |
| 2.5, 5, 7.5, or 10 mg | Not starting or target doses | Not used in these regimens |
| 4 mg | A target dose, and also a starting dose for some groups | A target dose in some trials, or the second step for higher groups |
| 6 mg | Not a starting or target dose | A step only, not a target |
| 8 mg | A target dose | Not used in these regimens |
| 9 mg | Not a starting or target dose | A target dose, or the last step before 12 mg |
| 12 mg | The highest target (started at 2 mg) | The highest target |
Sources: Phase 2 obesity trial, NEJM 2023; Phase 2 diabetes trial, The Lancet 2023; Lilly Phase 3 methods linked above. The Phase 2 column identifies starting and target doses, not every intermediate step. These were once-weekly injection studies, not an inventory of every retatrutide experiment.
So an 8 mg target can come from the Phase 2 obesity trial, while a 9 mg target can come from the Phase 3 trials above. Neither one means you swap one for the other. They're just different study designs.
One correction matters: 1 mg was not the lowest dose ever studied. A separate Phase 2 diabetes trial tested 0.5 mg weekly. An earlier Phase 1b diabetes study also included 0.5 mg, 1.5 mg, 3 mg, and groups escalating through 6 mg. Those findings do not validate an online seller's “microdosing” plan (Phase 2; Phase 1b).
Looking for treatment you can access now instead? The right GLP-1 path isn't the same for everyone. It depends on your state, your insurance and formulary (your plan's list of covered drugs), whether an FDA-approved or compounded medicine fits your medical needs, whether you'd rather take a shot or a pill, and your budget. Compounded medicines are not FDA-approved; retatrutide cannot be compounded. The RX Index's Find My GLP-1 Path tool is free, takes about 2 minutes, and needs no signup. Answer a few quick questions to see a suggested path and provider options. It does not choose a retatrutide dose or arrange trial access.
What did each retatrutide dose do in the trials?
Higher target groups had more average weight loss in the five trials below. In the three trials with 4, 9 and 12 mg targets, the 9-to-12 mg gap was smaller than the 4-to-9 mg gap. Stopping after adverse events usually went up. TRIUMPH-2, which included type 2 diabetes, reported less weight loss at each matching target than TRIUMPH-1, which did not. That's a comparison across studies—not proof that diabetes alone explains the difference.
Two kinds of numbers show up in headlines, and they answer different questions. That's why you see both 25.0% and 28.3% for the same 12 mg group.
- Efficacy estimand: estimated results assuming people stayed on study treatment, with allowed dose changes, without adding the other treatments excluded by that analysis. Lilly leads with this one.
- Treatment-regimen estimand: estimated results regardless of whether people stayed on study treatment or added those other treatments. It includes stopping treatment, but it is still a trial estimate—not a real-world study.
(An estimand is just the exact question a trial's math is built to answer.) Neither number replaces the other. They're two honest answers to two different questions, not simply averages of people who finished versus people who quit. In TRANSCEND-T2D-1, the extra treatments were glucose-lowering medicines; in the TRIUMPH weight analyses, they were prohibited weight-management treatments.
| Trial (length) | Who was in it | Dose | Efficacy estimand | Treatment-regimen estimand |
|---|---|---|---|---|
| TRIUMPH-1 (80 weeks) | 2,339 adults with obesity or overweight, no diabetes | 4 mg | 19.0% | 17.6% |
| 9 mg | 25.9% | 23.7% | ||
| 12 mg | 28.3% | 25.0% | ||
| Placebo | 2.2% | 3.9% | ||
| TRIUMPH-2 (80 weeks) | 1,152 adults with obesity or overweight and type 2 diabetes | 4 mg | 12.7% | 11.9% |
| 9 mg | 19.1% | 16.8% | ||
| 12 mg | 20.8% | 18.8% | ||
| Placebo | 4.0% | 5.1% | ||
| TRIUMPH-3 (80 weeks) | 1,949 adults with BMI 35+ and heart disease, with or without diabetes | 9 mg | 21.6% | Not in the July release |
| 12 mg | 22.6% | Not in the July release | ||
| Placebo | 3.2% | Not in the July release | ||
| TRIUMPH-4 (68 weeks) | 445 adults with obesity or overweight and knee osteoarthritis, no diabetes | 9 mg | 26.4% | 20.0% |
| 12 mg | 28.7% | 23.7% | ||
| Placebo | 2.1% | 4.6% | ||
| TRANSCEND-T2D-1 (40 weeks) | 537 adults with type 2 diabetes inadequately controlled by diet and exercise alone | 4 mg | 11.5% | 11.5% |
| 9 mg | 15.5% | 13.9% | ||
| 12 mg | 16.8% | 15.3% | ||
| Placebo | 2.5% | 2.6% |
Average percent of starting body weight lost, not percent lost versus placebo. BMI means body mass index, a measure based on height and weight. Sources: Lilly releases for TRIUMPH-1 (May 21, 2026), TRIUMPH-2 and TRIUMPH-3 (July 23, 2026), TRIUMPH-4 (December 11, 2025), and TRANSCEND-T2D-1 (March 19, 2026). Treatment-regimen figures were also checked against the peer-reviewed abstracts for TRIUMPH-1, published in NEJM on September 29, 2026, and TRIUMPH-2 and TRANSCEND-T2D-1 in The Lancet. “Not in the July release” is not zero. These are trial averages, not promises; different populations and follow-up times prevent a simple ranking across studies.
Want the full breakdown of these results? See retatrutide weight loss results.
What the higher target actually added to the average
People were randomly assigned to their target inside each trial. That makes comparisons within the same trial more useful than comparing unrelated studies. Here's what our math shows when you line them up—not a test of what would happen if one person raised their dose.
| Trial | Difference between 12 mg and 9 mg group averages (efficacy) | Stopped after adverse events: 9 mg → 12 mg |
|---|---|---|
| TRIUMPH-1 | +2.4 points (25.9% → 28.3%) | 6.9% → 11.3% |
| TRIUMPH-2 | +1.7 points (19.1% → 20.8%) | 11.6% → 7.7% |
| TRIUMPH-3 | +1.0 point (21.6% → 22.6%) | 9.8% → 13.5% |
| TRIUMPH-4 | +2.3 points (26.4% → 28.7%) | 12.2% → 18.2% |
| TRANSCEND-T2D-1 | +1.3 points (15.5% → 16.8%) | 4.5% → 5.1% |
Our subtraction from Lilly's published figures above; “points” means percentage points. These are descriptive differences, not proof that each dose pair differed statistically. “Stopped after adverse events” follows the sponsor's discontinuation measure; an event is not automatically caused by the drug. TRIUMPH-2's peer-reviewed abstract labels this category “adverse events or death.” TRIUMPH-4's count included stopping for perceived excessive weight loss.
Compare that with the 6.9-point gap between the 4 mg and 9 mg groups in TRIUMPH-1. The gap between the two highest targets was smaller. These are end-of-trial group averages—not weight lost on each flight of the staircase.
And the 4 mg group is worth a closer look. In TRIUMPH-1 it had 19.0% estimated average weight loss under the efficacy analysis, with one planned step up. Fewer people stopped after adverse events on 4 mg (4.1%) than on placebo (4.9%). The same pattern showed up in TRIUMPH-2 (3.8% vs 4.9%). That does not prove 4 mg was safer than placebo.
One oddity: in TRIUMPH-2, more people stopped after adverse events at 9 mg than at 12 mg. The reports checked here don't establish why, and we won't guess.
None of this tells anyone which dose to take. It tells you the honest shape of the trade: the highest target had the largest average weight loss, but weight loss wasn't the only outcome that mattered.
The tradeoff charts leave out
A weight-loss number doesn't show how people felt. Nausea was more common in the higher-target groups below, but not every stomach side effect rose at each dose. In the Phase 2 obesity trial and TRANSCEND-T2D-1, stomach events occurred mainly during dose escalation.
| Trial | Assigned target | Nausea | Vomiting | Stopped after adverse events |
|---|---|---|---|---|
| TRIUMPH-1 | 4 mg | 28.6% | 10.6% | 4.1% |
| 9 mg | 38.4% | 22.8% | 6.9% | |
| 12 mg | 42.4% | 25.3% | 11.3% | |
| Placebo | 14.8% | 4.8% | 4.9% | |
| TRIUMPH-2 | 4 mg | 13.7% | 5.5% | 3.8% |
| 9 mg | 20.8% | 10.2% | 11.6% | |
| 12 mg | 28.0% | 15.7% | 7.7% | |
| Placebo | 8.0% | 4.2% | 4.9% | |
| TRIUMPH-3 | 9 mg | 21.7% | Not in the July release | 9.8% |
| 12 mg | 22.4% | Not in the July release | 13.5% | |
| Placebo | 5.8% | Not in the July release | 4.8% | |
| TRIUMPH-4 | 9 mg | 38.1% | 20.4% | 12.2% |
| 12 mg | 43.2% | 20.9% | 18.2% | |
| Placebo | 10.7% | 0.0% | 4.0% | |
| TRANSCEND-T2D-1 | 4 mg | 16.4% | 15.7% | 2.2% |
| 9 mg | 19.5% | 15.0% | 4.5% | |
| 12 mg | 26.5% | 17.6% | 5.1% | |
| Placebo | 3.7% | 2.2% | 0.0% |
Sources: Lilly's dated releases linked above, using each trial's population and treatment period. An adverse event is any health problem recorded during a study, whether or not the drug caused it. TRIUMPH-2's abstract includes adverse events or death in its stopping category; TRIUMPH-4's included perceived excessive weight loss. Missing figures are not zero. This is a selected slice, not the full safety picture.
For dysesthesia (a burning or tingly skin feeling), heart rate, and warning signs, see retatrutide side effects by trial.
What is the maximum dose of retatrutide?
The highest assigned target in the Phase 2 obesity study and five Phase 3 trials above was 12 mg once a week. In TRIUMPH-1's extension, 532 selected participants with a starting BMI of 35 or more moved to a maximum tolerated dose of 9 or 12 mg. Those originally assigned 12 mg had an estimated 30.3% weight loss at 104 weeks under the efficacy analysis (29.9% under the treatment-regimen analysis). The extension required completing 80 weeks without stopping treatment or a permanent dose reduction, so this was a selected group who tolerated treatment—not the full original trial population (Lilly, May 21, 2026).
12 mg is not an FDA-approved maximum. Nothing is, yet.
Is Lilly still changing the retatrutide dose plan?
Yes. Two Phase 3b trials are testing how fast to ramp up and what dose to stay on over the long run. The registry records checked here do not give the exact doses. A future approved schedule is not established by these trial designs.
| Trial | What it's testing | Planned size | Follow-up and estimated study completion | Status (checked Oct 14, 2026) |
|---|---|---|---|---|
| TRIUMPH-9 | Three different ramp-up schedules, labeled 1, 2, and 3 | About 600 adults without diabetes | Main outcome at week 104; estimated study completion November 2028 | Active, not recruiting |
| TRIUMPH-6 | After 80 weeks on "dose 1," people stay on it, switch to "dose 2," or switch to placebo for 36 weeks | About 643 adults with obesity | Main outcome at week 116; estimated study completion April 2028 | Active, not recruiting |
These are estimated study-completion dates, not promised publication dates. The Phase 3 ladder on this page is a documented research plan. It may not be the ladder on a future label.
Why do retatrutide dose charts online disagree?
Charts can disagree because they mix studies, borrow numbers from vial sizes, or copy community "protocols." The 2 → 4 → 6 → 9 → 12 mg ladder matches the higher-target groups in the five Phase 3 trials above. Even that one is a study design, not an approved dose.
Here's how the charts people actually run into stack up against the trials.
| What you saw | Verdict | Why |
|---|---|---|
| Start at 2 mg, step up every 4 weeks to 4, 9, or 12 mg | Matches the Phase 3 studies above | Lilly's published methods. Still a study plan, not a prescription. |
| Start at 1 mg | Not the Phase 3 start above | 1 mg was its own Phase 2 obesity group. The five Phase 3 studies above used a 2 mg start. |
| Start at 0.25 or 0.5 mg, or "microdose" | Different claims—not one verdict | 0.5 mg was studied in Phase 1b and Phase 2 diabetes trials; 0.25 mg was not a dose in the regimens compared here. Neither fact validates a seller's personal dosing plan. |
| An 8 mg target | Matches the Phase 2 obesity trial | The five Phase 3 studies above instead used 9 mg among their targets and 6 mg as an intermediate step. |
| 2.5, 5, 7.5, or 10 mg doses | Not the regimens compared here | These are not starting or target doses in the Phase 2 obesity trial or steps in the five Phase 3 schedules above. |
| "3 to 6 mg maintenance" or a "24-week titration" | Not the Phase 3 plan above | 3 and 6 mg did appear in early Phase 1b research. They were not target groups in the five Phase 3 studies above, whose planned 12 mg target began in week 17. |
| Every other day, or splitting the weekly dose | Not the schedules reported here | The studies compared here used weekly injections. They do not establish that splitting a weekly dose works the same way. |
| Stack it with tirzepatide | Not supported by these studies | Zepbound's prescribing information says use with another GLP-1 receptor agonist is not recommended. Retatrutide acts on that receptor. |
| A dose written in "units" | Not enough information | A syringe marking and an amount in milligrams are not interchangeable without a verified concentration and the correct syringe. |
| A missed-dose rule | Check whose rule it is | No FDA-approved retatrutide label gives one. A trial has its own protocol; participants should ask their study team rather than borrow another drug's instructions. |
Sources: the trial reports above; Phase 1b diabetes study; Phase 2 diabetes study; Zepbound prescribing information, revised August 2026; FDA's dosing-error alert.
The "retatrutide label" on DailyMed
If you searched DailyMed, the government's drug-label library, you may have found what looks like an official retatrutide label with a dosing schedule. It isn't Lilly's drug, and it isn't approved.
When we checked on October 14, 2026, that listing named Guangzhou Yixin Cross-border E-commerce Co., Ltd. as its packager and was marked "Export only." Its schedule climbs from 2.5 mg to 10 mg, which does not match the Lilly regimens compared here. The FDA says a drug listing or NDC number does not mean FDA approval, and that the company that files a listing is responsible for what it says.
A label on a database tells you what a company claims. It doesn't tell you what's in the vial.
How many units is 2 mg of retatrutide?
There is no universal number of syringe units for 2 mg of retatrutide. The studies above report drug amounts in milligrams; syringe markings measure a volume. A conversion needs a verified drug concentration and the correct syringe. “Units” also appear with pharmacy-dispensed medicines—not just powders mixed at home.
We know this is the question a lot of people came here to ask. We're not going to give you an injection amount, because the honest answer is that no number on any website can tell you what's in your vial. Here's what to tell a clinician.
That isn't us being cautious for show. Lilly says illicit retatrutide products may contain unknown ingredients and contaminants, and too much or too little of the active ingredient. The FDA has received reports of adverse events, some requiring a hospital, linked to dosing errors with compounded injectable semaglutide. Patients sometimes measured doses incorrectly; clinicians sometimes miscalculated them (FDA dosing-error alert). Those are semaglutide reports, not a measured rate of harm from retatrutide.
Here's what actually helps if you're holding a vial. Tell a clinician the truth. You can use this sentence word for word:
"I've been using a product sold as retatrutide. I don't know exactly what's in it. I started around [date], last took about [amount] on [date], and here's what I've noticed."
Bring the vial, the box, and the receipt if you have them. If you don't know an amount, say so—don't guess. You can ask for help without having every detail, and you shouldn't delay care to find the packaging.
Is it safe to dose retatrutide from a "research" vial?
A "research use only" label does not verify a vial's contents, and the trial numbers on this page came from Lilly's study product given under medical supervision. The FDA says retatrutide cannot be used in compounding under federal law, and it has warned companies that sell it as "for research purposes" or "not for human consumption" with dosing instructions.
The trial results do not establish the safety of an online vial. They describe a known study product, in selected populations, with medical monitoring. Neither statistical analysis in the results table can tell you the risk of a product with unverified contents.
For how to spot fake or unsafe GLP-1 products, see how to avoid fake GLP-1 medications online. For enforcement actions, see our compounded GLP-1 enforcement tracker.
When will there be an approved retatrutide dose?
Only if the FDA approves it. Lilly announced plans to submit its application in the first quarter of 2027. Filing is not approval or a launch date. An approved label could use a different starting dose, different steps, or different target doses than the trials did. Lilly is still testing ramp-up speeds and long-term doses.
The documented medical access paths to Lilly's retatrutide are a clinical trial or its expanded-access program. The program is listed as available, but it's narrow. Your treating doctor must request it. The posted criteria include being 18 or older, a BMI of 35 or higher despite taking and tolerating the highest available chronic weight-management dose, and at least two serious or life-threatening obesity-related complications under treatment. A suitable retatrutide or comparable trial must be unavailable to you, and standard options—including weight-loss surgery—must have been discussed (ClinicalTrials.gov NCT07629401, last updated August 6, 2026).
Meeting the listed criteria does not guarantee access: geography, supply and individual review also matter. The full rules, trial status, and timeline are on our retatrutide availability page.
Wondering what it might cost when it does arrive? See retatrutide cost predictions.
How does retatrutide dosing compare with Zepbound and Wegovy?
The injection forms compared here are weekly shots that start low and step up over time. The difference is that Zepbound and Wegovy injections have FDA-approved dose charts and missed-dose rules, and can be filled by pharmacies with a prescription. Retatrutide has no FDA-approved label or routine retail prescription. This table does not cover Wegovy tablets.
| Retatrutide (investigational) | Zepbound (tirzepatide) | Wegovy pen (semaglutide) | |
|---|---|---|---|
| FDA-approved? | No | Yes | Yes |
| How often | Once a week | Once a week | Once a week |
| Starting dose in the cited schedule | 2 mg in the five Phase 3 trials above | 2.5 mg | 0.25 mg |
| Doses | Assigned targets of 4, 9, or 12 mg across these trials | Strengths from 2.5 to 15 mg; maximum 15 mg weekly | Standard adult weight-management maintenance is 1.7 or 2.4 mg; 7.2 mg (Wegovy HD) is an option for certain adults |
| FDA-approved missed-dose rule? | No; study participants follow their protocol | Yes | Yes |
| Available as an approved retail prescription? | No | Yes, with a prescription | Yes, with a prescription |
Sources: Lilly trial methods above; Zepbound prescribing information, revised August 2026; Wegovy prescribing information, revised June 2026. Wegovy 7.2 mg is an adult weight-reduction option after at least four weeks tolerating 2.4 mg when additional weight reduction is needed. It is not the maximum for every age or indication. Full approved charts: Zepbound dose chart and semaglutide vs tirzepatide dosage chart.
Don't compare milligrams across drugs. Retatrutide and tirzepatide are different molecules, so comparing 12 mg of one with 15 mg of the other doesn't tell you which is stronger. If you're curious how the two drugs really compare, see retatrutide vs tirzepatide. For why retatrutide works on three hormone targets instead of two, see triple vs dual agonist weight loss.
What should you do next?
The right next step depends on where you are. A trial chart can't replace your study team or a clinician, so pick the row that fits.
| Your situation | Next step |
|---|---|
| You're in a retatrutide trial and have a dose, missed-dose, or side-effect question | Call your study team, using the contact details they gave you. |
| You want to see if a trial might fit you | Read the official retatrutide study listings, then call the listed site to check current status and rules. |
| You took a product sold as retatrutide and feel unwell, or think you made a dosing error | In the U.S., call Poison Control at 1-800-222-1222 (free, 24/7). |
| Someone collapses, has a seizure, has trouble breathing, or can't be woken up | Call 911 right away in the U.S. Elsewhere, call your local emergency number. |
| You want treatment now, not more research | Talk with a clinician about FDA-approved options. The tool earlier on this page can show you which paths fit before that visit. |
| You don't know your BMI, plan type, or coverage | You don't need any of that to understand this page. Gather it with your clinician or insurer before you choose a treatment path. |
Emergency guidance: Poison Control first aid; free, 24-hour phone help and what to tell the specialist.
If you're under 18, pregnant or planning to be, have type 1 diabetes, have a history of an eating disorder, or have a personal or family history of medullary thyroid cancer or multiple endocrine neoplasia type 2 (MEN 2), start with your own clinician. These situations need individual medical guidance; they are not all the same kind of restriction. Our guide to GLP-1 hard contraindications explains which conditions rule out particular approved drugs.
Thinking about waiting? Talk with your clinician about what delaying treatment would mean for you. If you decide to wait, give it a date: check back after Lilly's planned early-2027 filing instead of refreshing headlines. A filing still isn't an approval.
What we actually verified
We built this page from Lilly's trial reports, the original Phase 2 obesity paper, published study abstracts, government trial records, and the FDA's own statements. Where a number is our own math, we say so. Where a source does not report a number, we leave it unknown.
Checked October 14, 2026:
- Lilly's TRIUMPH-4 (December 11, 2025), TRANSCEND-T2D-1 (March 19 and June 6, 2026), TRIUMPH-1 (May 21, 2026), and TRIUMPH-2 and TRIUMPH-3 (July 23, 2026) releases, for the reported study schedules, weight-loss estimates and selected adverse-event rates
- The full NEJM Phase 2 obesity article and its Table 3; the PubMed abstracts for the Phase 1b and Phase 2 diabetes studies, TRIUMPH-1 (NEJM, September 29, 2026), and TRIUMPH-2 and TRANSCEND-T2D-1 (The Lancet)
- ClinicalTrials.gov records for TRIUMPH-6, TRIUMPH-9, and Lilly's expanded-access program, including status, estimated completion dates and posted criteria
- The FDA's pages on unapproved GLP-1 drugs, compounded semaglutide dosing errors, and the NDC Directory
- Lilly's “What to know about retatrutide” page and the DailyMed listing's named packager and “Export only” status
- Zepbound and Wegovy prescribing information, including the limits on the adult Wegovy 7.2 mg option, and Poison Control's emergency guidance
- The live Find My GLP-1 Path landing page and its metadata; this was not a test of every result or provider match
Our own math: planned weeks to reach each target, and differences between assigned groups in the “higher target” table. For example, 28.3 minus 25.9 is 2.4 percentage points—not a 2.4% increase in the amount of weight lost.
What remains unknown: any future approved dose and the exact doses omitted from the TRIUMPH-6 and TRIUMPH-9 registry entries. We did not verify each Phase 2 arm's full week-by-week sequence, so it is not reproduced here. We read the Phase 3 peer-reviewed abstracts, not their full subscription articles or supplements. We did not independently analyze patient-level trial data.
What we didn't do: we didn't buy, test, or use any product, and this page has no medical reviewer.
The RX Index is the independent GLP-1 decision resource that scores telehealth providers and treatment paths on clinical legitimacy, care quality, transparency, access, and cost, so readers can choose the path that fits their situation.
Learn how we evaluate evidence and how to read GLP-1 clinical trials.
Retatrutide dosing FAQ
What is the starting dose of retatrutide?
In the five Phase 3 trials compared here, the starting dose was 2 mg once a week. The earlier Phase 2 obesity trial used 1, 2, or 4 mg starts depending on the group; a separate diabetes trial included 0.5 mg. There's no FDA-approved starting dose (trial dose chart; Phase 2 diabetes study).
Can you start retatrutide at 4 mg?
Some Phase 2 obesity groups started at 4 mg, and stomach side effects were partly reduced in groups that started at 2 mg. The five Phase 3 studies above used a 2 mg start. That history does not give anyone an approved or personal starting dose (NEJM Phase 2 report).
Can someone stay on a lower dose of retatrutide?
In some trials, people were assigned to stay on 4 mg instead of climbing to 12 mg. In TRIUMPH-1, that group had 19.0% estimated weight loss at 80 weeks under the efficacy analysis (17.6% under the treatment-regimen analysis). Fewer stopped after adverse events than on placebo, but that does not establish greater safety. That's a trial result, not a personal plan (Lilly TRIUMPH-1 report).
How long does it take to reach 12 mg of retatrutide?
In the five Phase 3 schedules above, the planned escalation took 16 weeks. The 12 mg target began in week 17, after four weeks each at 2, 4, 6, and 9 mg. That is protocol timing, not advice to raise a dose (trial dose chart).
Does my Mounjaro or Zepbound dose tell me a retatrutide dose?
No FDA-approved conversion exists between tirzepatide and retatrutide. The studies compared here assigned research doses; they do not supply a personal switching rule. They're different drugs, so a dose of one doesn't tell you what dose of the other to use (FDA status; trial methods).
Is retatrutide taken daily or weekly?
The studies compared here gave it once a week as an injection under the skin. They do not establish that daily, every-other-day, or split dosing works the same way or has the same safety profile (trial methods).
Can you take retatrutide with tirzepatide?
The studies compared here do not establish the safety or benefit of that combination. Zepbound's prescribing information says use with another GLP-1 receptor agonist is not recommended, and retatrutide acts on the GLP-1 receptor. Discuss treatment changes with your own clinician.
Does body weight decide the retatrutide dose?
Body weight alone does not give a retatrutide dose. In the trials compared here, target doses were assigned by random group, not by a milligram-per-kilogram formula. The tables cannot turn your weight or BMI into a personal dose (trial methods).
What happens after a missed dose of retatrutide?
There is no FDA-approved retatrutide label with a missed-dose rule. That does not mean trials lack instructions: participants should call their study team for their own protocol. Don't borrow the missed-dose rule from Zepbound or Wegovy; those rules were written for those drugs. (For approved drugs, see Wegovy and Zepbound missed-dose rules.)
Will the approved retatrutide dose match the trials?
Not necessarily. Lilly is still testing ramp-up schedules in TRIUMPH-9 and long-term doses in TRIUMPH-6. Any FDA-approved schedule would be set out in an approved label. The Phase 3 ladder is research history, not a promise of that label.
Is compounded retatrutide an option?
No. The FDA says retatrutide cannot be used in compounding under federal law. A seller calling a product "compounded" or "research use only" does not establish a lawful human-treatment product or FDA approval.
Is retatrutide FDA-approved?
No. Retatrutide remains investigational. A trial and a narrow, physician-requested expanded-access program are documented medical access paths—not FDA approval. Lilly's announced filing plan is the first quarter of 2027, not a guaranteed approval date.
Sources
Checked October 14, 2026 unless noted.
- Eli Lilly, TRIUMPH-4 results (December 11, 2025): https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-delivered-weight-loss-average
- Eli Lilly, TRANSCEND-T2D-1 full topline weight table (March 19, 2026): https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-demonstrated-significant
- Eli Lilly, TRIUMPH-1 topline results (May 21, 2026): https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-delivered-powerful-weight-loss
- Eli Lilly, TRIUMPH-1 detail and TRANSCEND-T2D-1 results (June 6, 2026): https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-drove-substantial-improvements
- Eli Lilly, TRIUMPH-2 and TRIUMPH-3 results and BLA plan (July 23, 2026): https://investor.lilly.com/news-releases/news-release-details/lillys-triple-agonist-retatrutide-successful-two-additional
- Eli Lilly, "What to know about retatrutide" (last updated September 2026): https://www.lilly.com/news/stories/what-to-know-about-retatrutide
- Jastreboff AM et al., Phase 2 obesity trial, NEJM (online June 26, 2023; issue August 10, 2023), full article and Table 3: https://www.nejm.org/doi/full/10.1056/NEJMoa2301972
- Rosenstock J et al., Phase 2 diabetes trial, The Lancet (2023), abstract: https://pubmed.ncbi.nlm.nih.gov/37385280/
- Urva S et al., Phase 1b diabetes trial, The Lancet (online October 27, 2022), abstract: https://pubmed.ncbi.nlm.nih.gov/36354040/
- Jastreboff AM et al., TRIUMPH-1, NEJM (September 29, 2026): https://pubmed.ncbi.nlm.nih.gov/42814954/
- TRIUMPH-2, The Lancet (2026): https://pubmed.ncbi.nlm.nih.gov/42810372/
- TRANSCEND-T2D-1, The Lancet (2026): https://pubmed.ncbi.nlm.nih.gov/42250575/
- ClinicalTrials.gov, TRIUMPH-9: https://clinicaltrials.gov/study/NCT07357415
- ClinicalTrials.gov, TRIUMPH-6: https://clinicaltrials.gov/study/NCT06859268
- ClinicalTrials.gov, Pre-approval expanded access of retatrutide: https://clinicaltrials.gov/study/NCT07629401
- ClinicalTrials.gov, retatrutide study listings: https://clinicaltrials.gov/search?intr=Retatrutide
- FDA, "FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss" (checked October 14, 2026): https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss
- FDA, National Drug Code Directory: https://www.fda.gov/drugs/drug-approvals-and-databases/national-drug-code-directory
- FDA, dosing errors associated with compounded injectable semaglutide: https://www.fda.gov/drugs/human-drug-compounding/fda-alerts-health-care-providers-compounders-and-patients-dosing-errors-associated-compounded
- Zepbound U.S. prescribing information (revised August 2026): https://pi.lilly.com/us/zepbound-uspi.pdf
- Wegovy U.S. prescribing information (revised June 2026): https://www.novo-pi.com/wegovy.pdf
- DailyMed, retatrutide listing checked for packager and marketing status only (set ID 425d04f6-6fb2-5c7a-e063-6394a90aa87d; listing updated October 30, 2025). Not an FDA-approved prescribing source.
- Poison Control, first aid for poisonings: https://www.poison.org/first-aid-for-poisonings
- Poison Control, phone help, hours and information to provide: https://www.poison.org/how-to-get-help-from-poison-control
- The RX Index, Find My GLP-1 Path landing page and metadata: https://therxindex.com/find-my-path/