Metabolic · Dosing reference

Retatrutide dosage

Doses given in registered human trials, how long they ran, and the arithmetic for working with vials.

InvestigationalAHuman trial evidenceTrial doses

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Regulatory status: Investigational
Human amounts: Phase 2: 0.5–12 mg once weekly (36–48 weeks); phase 3 (TRIUMPH-1, TRIUMPH-2, TRANSCEND-T2D-1): 4, 9 or 12 mg once weekly
Route studied: Subcutaneous injection
Frequency: Once weekly
Half-life: Approximately 6 days (phase 1b multiple-ascending-dose study in type 2 diabetes)
Evidence grade: Grade A · Human trial evidence
Vial sizes on the market: 5 mg · 10 mg · 12 mg · 20 mg · 24 mg · 30 mg · 48 mg · 60 mg
Other forms seen: —

What Retatrutide is

Retatrutide is an investigational peptide that acts on three receptors (glucagon, GIP and GLP-1) and is given by weekly subcutaneous injection in clinical trials. Published phase 2 and 2026 phase 3 randomized trials have reported large mean body-weight reductions and HbA1c reductions versus placebo, with gastrointestinal events the most commonly reported adverse events. It is not approved for any use, and this entry summarizes the published and registered trials for research reference only.

Retatrutide (LY3437943) is described in the literature as a single peptide with agonist activity at the glucose-dependent insulinotropic polypeptide (GIP), GLP-1 and glucagon receptors ^2. Receptor pharmacology In a discovery-to-proof-of-concept report, in vitro activity at the glucagon and GLP-1 receptors was described as balanced, with relatively more activity at the GIP receptor ^6. In obese mice, the same… How it works →

Key evidence

Jastreboff et al., N Engl J Med (phase 2, obesity) · 2023 · Humans (adults with obesity, or overweight with a weight-related condition)
Least-squares mean body-weight change at 48 weeks was -8.7%, -17.1%, -22.8% and -24.2% across the retatrutide groups versus -2.1% with placebo; gastrointestinal events were dose-related and mostly mild to moderate, and dose-dependent heart-rate increases peaked at 24 weeks and declined thereafter ^1. ¹
Rosenstock et al., Lancet (phase 2, type 2 diabetes) · 2023 · Humans (adults with type 2 diabetes, HbA1c 7.0% to 10.5%)
At 24 weeks, HbA1c change ranged from -0.43% to -2.02% across retatrutide groups versus -0.01% with placebo and -1.41% with dulaglutide; body weight decreased dose-dependently by up to 16.94% at 36 weeks versus 3.00% with placebo ^2. ²
TRIUMPH-1 investigators, N Engl J Med (phase 3, obesity) · 2026 · Humans (adults with obesity without diabetes)
Mean body-weight change was -17.6%, -23.7% and -25.0% across three retatrutide dose levels versus -3.9% with placebo; WOMAC pain scores in the knee osteoarthritis subgroup and apnea-hypopnea index in the sleep apnea subgroup also changed more than with placebo, and the most common adverse events were gastrointestinal ^3. ³

All studies on the research page

Schedules by time period

study arms from registered trials, laid out week by week. Each bar is what the label states or what investigators gave participants; none is a recommendation.

Registered trial

Phase 2 obesity trial (NCT04881760): study arms ^7,1

Adults with BMI 30 or higher, or 27 to under 30 with at least one weight-related condition (338 enrolled) · 48 weeks

1 mg (no escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–48	1 mg (maintenance)

4 mg (start 2 mg)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–48	4 mg (maintenance)

4 mg (start 4 mg)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–48	4 mg (maintenance)

8 mg (start 2 mg)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–8	4 mg
Weeks 8–48	8 mg (maintenance)

8 mg (start 4 mg)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	4 mg
Weeks 4–48	8 mg (maintenance)

12 mg (start 2 mg)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–8	4 mg
Weeks 8–12	8 mg
Weeks 12–48	12 mg (maintenance)

The protocol posted on ClinicalTrials.gov specifies a 48-week treatment period with an up-to-12-week escalation period; the dose was increased at 4-week increments from randomization (week 0) until the maintenance dose was reached. A placebo arm also received matched injections.

Registered trial

Phase 2 type 2 diabetes trial (NCT04867785): study arms ^16,2

Adults 18-75 years with type 2 diabetes (HbA1c 7.0-10.5%, BMI 25-50) on diet and exercise with or without metformin (281 randomized) · 36 weeks

0.5 mg (no escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–36	0.5 mg (maintenance)

4 mg (start 2 mg, slow escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–36	4 mg (maintenance)

4 mg (no escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–36	4 mg (maintenance)

8 mg (start 2 mg, slow escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–8	4 mg
Weeks 8–36	8 mg (maintenance)

8 mg (start 4 mg, rapid escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	4 mg
Weeks 4–36	8 mg (maintenance)

12 mg (start 2 mg, slow escalation)

SC · once weekly

Week-by-week table

Period	Amount
Weeks 0–4	2 mg
Weeks 4–8	4 mg
Weeks 8–12	8 mg
Weeks 12–36	12 mg (maintenance)

Protocol table: weeks 0-3, 4-7 and 8-11 form a 12-week escalation period; weeks 12-35 are the maintenance period. Comparator arms received dulaglutide 1.5 mg or placebo once weekly.

Registered trial

Phase 3 TRIUMPH-1 (NCT05929066): study arms ³

Adults with obesity (or overweight) without diabetes, including subgroups with knee osteoarthritis and obstructive sleep apnea (2339 randomized) · 80 weeks

4 mg

SC · once weekly

4 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

9 mg

SC · once weekly

9 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

12 mg

SC · once weekly

12 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

Once-weekly subcutaneous retatrutide or placebo for 80 weeks (publication abstract). The registry record lists doses only as "Dose 1-3" and an additional 24-week retatrutide extension period after week 80 without amounts. Escalation steps not reported in the cited source.

Registered trial

Phase 3 TRIUMPH-2 (NCT05929079): study arms ⁴

Adults with BMI 27 or higher and type 2 diabetes (HbA1c 6.5-10.5%) (1152 randomized) · 80 weeks

4 mg

SC · once weekly

4 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

9 mg

SC · once weekly

9 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

12 mg

SC · once weekly

12 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

Once-weekly self-administered subcutaneous injections; primary endpoint at week 80. Escalation steps not reported in the cited source.

Registered trial

Phase 3 TRANSCEND-T2D-1 (NCT06354660): study arms ⁵

Adults with type 2 diabetes inadequately controlled by diet and exercise alone (HbA1c 7.0-9.5%, BMI 23 or higher) (537 randomized) · 40 weeks

4 mg

SC · once weekly

4 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

9 mg

SC · once weekly

9 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

12 mg

SC · once weekly

12 mg · Maintenance (start not reported)

Escalation steps not reported in the cited source.

40-week trial of once-weekly subcutaneous retatrutide or placebo. Escalation steps not reported in the cited source.

Doses given in human trials

In the phase 2 obesity trial (NCT04881760), participants received subcutaneous retatrutide once weekly for 48 weeks at 1 mg, 4 mg (initial dose 2 mg), 4 mg (initial dose 4 mg), 8 mg (initial dose 2 mg), 8 mg (initial dose 4 mg) or 12 mg (initial dose 2 mg), or placebo, randomized in a 2:1:1:1:1:2:2 ratio; the registry record lists stepwise escalation from the starting dose to the target dose in the escalated arms ^1,7.
In the phase 2 type 2 diabetes trial (NCT04867785), participants received once-weekly injections of placebo, dulaglutide 1.5 mg, or retatrutide at maintenance doses of 0.5 mg, 4 mg (starting dose 2 mg), 4 mg (no escalation), 8 mg (starting dose 2 mg), 8 mg (starting dose 4 mg) or 12 mg (starting dose 2 mg); the primary endpoint was HbA1c change at 24 weeks ^2.
In TRIUMPH-1 (NCT05929066), adults with obesity without diabetes received a once-weekly subcutaneous injection of retatrutide 4 mg, 9 mg or 12 mg, or placebo, for 80 weeks; the registry record also lists an optional retatrutide extension period of 24 additional weeks ^3,8.
In TRIUMPH-2 (NCT05929079), adults with obesity and type 2 diabetes were randomized 1:1:1:1 to once-weekly subcutaneous injections (self-administered) of placebo or retatrutide 4 mg, 9 mg or 12 mg, with the primary endpoint assessed at week 80 ^4,9.
In TRANSCEND-T2D-1 (NCT06354660), adults with type 2 diabetes inadequately controlled with diet and exercise were randomized 1:1:1:1 to once-weekly subcutaneous injections of retatrutide 4 mg, 9 mg or 12 mg, or placebo, for 40 weeks ^5,11.
In TRIUMPH-3 (NCT05882045, obesity with established cardiovascular disease) and TRIUMPH-4 (NCT05931367, obesity or overweight with knee osteoarthritis), the registry records list retatrutide administered subcutaneously at two dose levels versus placebo; the specific doses are not stated in the registry fields reviewed ^10,12.
In the phase 1b multiple-ascending-dose study (NCT04143802), adults with type 2 diabetes received once-weekly subcutaneous retatrutide 0.5 mg (n=9), 1.5 mg (n=9), 3 mg (n=11), 3/6 mg (n=11) or 3/6/9/12 mg (n=12), placebo (n=15) or dulaglutide 1.5 mg (n=5) for 12 weeks; the top doses in the two highest cohorts were reached by stepwise escalation ^14.
TRIUMPH-1 randomized 2,339 adults with obesity without diabetes to retatrutide 4, 9 or 12 mg or placebo once weekly for 80 weeks ^3.
TRIUMPH-2 randomized 1,152 adults with obesity and type 2 diabetes to retatrutide 4 mg (n=292), 9 mg (n=284) or 12 mg (n=287) or placebo (n=289) ^4.
TRANSCEND-T2D-1 randomized 537 participants: 134 to retatrutide 4 mg, 133 to 9 mg, 136 to 12 mg and 134 to placebo ^5.
In the nested OSA trials TRIUMPH-1-OSA (243 participants, without diabetes) and TRIUMPH-2-OSA (448 participants, with type 2 diabetes), adults with moderate-to-severe OSA and BMI of at least 27 received once-weekly subcutaneous retatrutide 4, 9 or 12 mg or placebo, with the primary endpoint at 80 weeks ^15.
In the phase 2 type 2 diabetes trial, 281 participants were randomized (2:2:2:1:1:1:1:2) across the placebo, dulaglutide and six retatrutide groups ^2.

How long did human studies run?

Phase 1b: 12 weeks of once-weekly dosing ^14. Phase 2 obesity trial: 48 weeks, primary endpoint at 24 weeks ^1. Phase 2 type 2 diabetes trial: primary endpoint at 24 weeks with secondary endpoints at 36 weeks ^2.
TRIUMPH-1 and TRIUMPH-2: 80 weeks of treatment; the TRIUMPH-1 registry also lists an optional 24-week retatrutide extension with a body-weight endpoint at week 104 ^3,4,8.
TRANSCEND-T2D-1: 40 weeks ^5. The TRIUMPH-3 registry lists a week-80 primary endpoint (1,946 enrolled) and the TRIUMPH-4 registry a week-68 primary endpoint (445 enrolled) ^10,12.

Cycle-length evidence for Retatrutide

Who was excluded from the studies

TRIUMPH-1 registry exclusion criteria include a body-weight change of more than 5 kg within 90 days, weight-loss drugs within 90 days before screening, prior or planned surgical treatment for obesity, diabetes mellitus, a personal or family history of medullary thyroid carcinoma or MEN 2, and a history of pancreatitis ^8.
TRIUMPH-2 enrolled adults with BMI of 27 or higher and type 2 diabetes (HbA1c 6.5–10.5%) on diet/exercise or up to three oral glucose-lowering medications ^4; TRANSCEND-T2D-1 enrolled adults with type 2 diabetes on diet and exercise alone with HbA1c 7.0–9.5% and BMI of at least 23 ^5.

Side effects reported in studies

Diarrhea
27% to 34% across retatrutide dose levels vs 13% placebo · TRIUMPH-2, adults with obesity and type 2 diabetes, 80 weeks ⁴
Nausea
14% to 28% across retatrutide dose levels vs 8% placebo · TRIUMPH-2, adults with obesity and type 2 diabetes, 80 weeks ⁴
Hypotension
1% to 6% across retatrutide dose levels vs less than 1% placebo · TRIUMPH-2, adults with obesity and type 2 diabetes ⁴
Dysesthesia
4% to 7% across retatrutide dose levels vs 1% placebo · TRIUMPH-2, adults with obesity and type 2 diabetes ⁴
Permanent discontinuation due to adverse events or death
4% to 12% across retatrutide dose levels vs 5% placebo · TRIUMPH-2, adults with obesity and type 2 diabetes ⁴
Nausea (phase 2, obesity)
28 of 62 (45%) in the highest-dose arm vs 8 of 70 (11%) placebo · Phase 2 obesity trial, 48 weeks (events reported at 5% or higher frequency in the registry record) ⁷
Vomiting (phase 2, obesity)
12 of 62 (19%) in the highest-dose arm vs 1 of 70 (1%) placebo · Phase 2 obesity trial, 48 weeks ⁷
Decreased appetite (phase 2, obesity)
18 of 62 (29%) in the highest-dose arm vs 6 of 70 (9%) placebo · Phase 2 obesity trial, 48 weeks ⁷

Full adverse-event data

Retatrutide draw calculator

Pick the vial strength and the water added, enter an amount, and see the concentration, the units to draw and how many draws the vial holds. Arithmetic only.

1 · Vial strength

sizes on the market

2 · Water added

3 · Amount per draw

4 · Syringe

Your mix

10 mg + 2 mL water = 5 mg/mL

10 units holds 0.5 mg (500 mcg)

Draw toEnter an amount in step 3

U-100 syringe · 100 units = 1 mL

Computed from your inputs. Not a dose or a recommendation.

Compare water volumes for this vialShow

More water = lower concentration = a larger, easier-to-measure draw. Tap a row to use it.

Water	mg/mL	Draw
0.5 mL	20	—
1 mL	10	—
1.5 mL	6.667	—
2 mL	5	—
2.5 mL	4	—
3 mL	3.333	—
5 mL	2	—

Supplies and handling

Lyophilized vial
Sealed vial with the freeze-dried cake. Check the label, lot and the certificate of analysis before opening.
Sterile diluent
The diluent named on the product documentation. Bacteriostatic water contains benzyl alcohol; sterile water does not.
Graduated syringes
Sized to the volume being measured. U-100 insulin syringes are graduated in units where 100 units = 1 mL.
Alcohol prep pads
For wiping vial stoppers before each puncture.
Nitrile gloves
Clean gloves for aseptic handling.
Sharps container
Puncture-resistant container for used needles.

Step-by-step reconstitution guide Storage and transport accessories

Storage

Handling of research material should follow the supplier's documentation and certificate of analysis, including storage temperature, protection from light and freeze-thaw limits. No approved-product storage instructions exist because retatrutide has no FDA label.

Lyophilized (unmixed) vials: typically stored cold and dry, away from light, as the documentation directs. Many are stable longer frozen.
Reconstituted vials: typically refrigerated (about 2–8 °C), protected from light and not frozen.
Bacteriostatic water contains benzyl alcohol, which inhibits bacterial growth in multi-use vials; sterile water has no preservative.

Handling mistakes and troubleshooting

Added the wrong volume of diluent: The concentration changes, not the amount of compound in the vial. Recalculate with the volume actually added and relabel the vial.
Shook the vial and it foamed: Let it settle in the refrigerator. Foam is a sign of agitation; some peptides aggregate when shaken. Note it on the label.
The solution is cloudy or has particles: Do not use it. Cloudiness can indicate incomplete dissolution, contamination or degradation. Record the lot and contact the supplier with the certificate of analysis.
The powder cake looks melted or shrunken before reconstitution: This can indicate the vial was exposed to heat or moisture. Record the lot and condition on arrival.
Liquid sprayed back when the needle was removed: Pressure built up in the vial. Withdraw a small volume of air while adding diluent to keep pressure neutral.

Regulatory status

Status: Not approved by the FDA; described in 2026 phase 3 publications as an agent under investigation for obesity, type 2 diabetes and related conditions including knee osteoarthritis and obstructive sleep apnea ^3,4,5. Phase 3 trials (TRIUMPH-1, TRIUMPH-2, TRIUMPH-3, TRIUMPH-4 and TRANSCEND-T2D-1) are registered on ClinicalTrials.gov with a status of completed ^{8,9,10,11,12.}
United States (FDA): Retatrutide is described in 2026 phase 3 publications as under investigation ^4,5, and its phase 3 trials are registered on ClinicalTrials.gov ^{8,9,10,11,12.}
Sport (WADA): Under class S0 of the WADA 2026 Prohibited List, any pharmacological substance not addressed elsewhere on the List and with no current approval by any governmental regulatory health authority for human therapeutic use, such as drugs under clinical development, is prohibited at all times ^13. Retatrutide is not named on the 2026 List ^13.

Status varies by country and changes over time. How we describe regulatory status.

Retatrutide compared with related compounds

Compound	Status	Evidence	Human amounts	Half-life
Retatrutide	Investigational	A	Trial doses	Approximately 6 days (phase 1b multiple-
Tesofensine	Investigational	B	Trial doses	About 234 hours (M1 metabolite about 374
Mazdutide	Approved outside the US	A	Trial doses	150.9 to 403.5 hours (phase 1b in overwe
Cagrilintide	Investigational	A	Trial doses	159 to 195 hours (phase 1b, co-administe
SLU-PP-332	Not approved — research use only	C	None established	Unknown in humans
MariTide (maridebart cafraglutide)	Investigational	A	Trial doses	Not reported numerically in the sources

Combinations that include Retatrutide

Frequently asked questions

What doses of Retatrutide have been studied in humans?

Retatrutide is investigational. This page lists the amounts given in each cited trial as facts about those studies.

Is there an established Retatrutide cycle length?

No cycle length or break has been established. Human studies administered Retatrutide for the periods listed on this page; those are study durations, not a recommended course.

How much bacteriostatic water should be added to a Retatrutide vial?

There is no compound-specific volume. The diluent volume only sets the concentration: concentration = mass in the vial ÷ volume added (for example, 10 mg in 2 mL gives 5 mg/mL). The calculator on this page shows the arithmetic for any combination.

How many units is a given amount on an insulin syringe?

On a U-100 syringe, 100 units = 1 mL. Units for an amount = amount ÷ (concentration per unit). The calculator converts any amount you enter at the concentration you choose; a unit is a volume mark, not an amount of compound.

What is the half-life of Retatrutide?

Approximately 6 days (phase 1b multiple-ascending-dose study in type 2 diabetes)

Is Retatrutide FDA-approved?

Investigational. Not approved by the FDA; described in 2026 phase 3 publications as an agent under investigation for obesity, type 2 diabetes and related conditions including knee osteoarthritis and obstructive sleep apnea ^3,4,5. Phase 3 trials (TRIUMPH-1, TRIUMPH-2, TRIUMPH-3, TRIUMPH-4 and TRANSCEND-T2D-1) are registered on ClinicalTrials.gov with a status of completed ^{8,9,10,11,12.}

References

Last reviewed October 23, 2026 by the Amiravo editorial team. Editorial policy · Report an error

What Retatrutide is

Key evidence

Schedules by time period

Phase 2 obesity trial (NCT04881760): study arms 7,1

Phase 2 type 2 diabetes trial (NCT04867785): study arms 16,2

Phase 3 TRIUMPH-1 (NCT05929066): study arms 3

Phase 3 TRIUMPH-2 (NCT05929079): study arms 4

Phase 3 TRANSCEND-T2D-1 (NCT06354660): study arms 5

Doses given in human trials

How long did human studies run?

Who was excluded from the studies

Side effects reported in studies

Retatrutide draw calculator

Supplies and handling

Storage

Handling mistakes and troubleshooting

Regulatory status

Retatrutide compared with related compounds

Combinations that include Retatrutide

Frequently asked questions

Compared with

Guides that mention this

Where sources disagree

Questions people ask

References

Phase 2 obesity trial (NCT04881760): study arms ^7,1

Phase 2 type 2 diabetes trial (NCT04867785): study arms ^16,2

Phase 3 TRIUMPH-1 (NCT05929066): study arms ³

Phase 3 TRIUMPH-2 (NCT05929079): study arms ⁴

Phase 3 TRANSCEND-T2D-1 (NCT06354660): study arms ⁵