Retatrutide Dosage Guide
Written by Alejandro Reyes
Founder & Lead Researcher
Reviewed by Peptide Nerds Editorial · Updated April 2026
Dosage overview
| Typical dose | 1 mg to 12 mg weekly (Phase 2/3 doses) |
| Frequency | Once weekly subcutaneous injection |
Dosing notes
Not yet FDA-approved — all dosing information reflects clinical trial protocols, not prescribing guidance. Phase 2 titration schedule used in published trials: 1 mg weekly for 4 weeks, then 2 mg for 4 weeks, then 4 mg for 4 weeks, then 8 mg for 4 weeks, then 12 mg maintenance. GI symptom rates nearly doubled when participants escalated too rapidly, making gradual titration critical for tolerability. Phase 3 TRIUMPH trials are testing 9 mg and 12 mg as maintenance doses, along with a 4 mg maintenance dose arm for patients who respond adequately at lower doses. The 12 mg dose consistently shows the greatest weight loss but also the highest side effect rates including the new dysesthesia signal. Storage in clinical trials: refrigerated at 2-8 degrees C (36-46 degrees F). Do not freeze. Protect from light. Retatrutide is not available through any legal channel outside of clinical trials. The FDA has stated it cannot be legally compounded under federal law. Any product marketed as retatrutide from research peptide vendors or compounding pharmacies is unregulated and unverified.
Important safety information
Dosage ranges listed above are based on available research data and reported protocols. Individual dosing should be determined by a qualified healthcare provider based on your specific health profile, goals, and response to treatment.
- Start at the lowest effective dose and titrate up gradually
- Monitor for side effects, especially during dose increases
- Do not exceed researched dose ranges without medical supervision
Interactive protocol guide
Step-by-step: your dosing schedule with exact syringe units, what supplies to buy, how to mix, and how to inject.
Retatrutide Protocol Overview
Goal
Weight loss
Duration
24 weeks
Route
subcutaneous
Important before you start:
- Retatrutide is investigational and not yet FDA-approved. Data is from clinical trials only.
- Triple-agonist (GLP-1/GIP/Glucagon). Report any unusual symptoms immediately.
- Nausea, diarrhea, and vomiting are the most common side effects during titration.
Your dosing schedule
Based on a 10 mg vial mixed with 2 mL bacteriostatic water (5.00 mg/mL concentration). Using a U-100 insulin syringe.
Draw to here
20 units
on 100-unit syringe
1-4: 1 mg
Click a row to update
| When | Dose | Syringe units | Frequency | What to expect |
|---|---|---|---|---|
| 1-4 | 1 mg | 20 units | Once weekly | Starting dose. Nausea and decreased appetite are expected. |
| 5-8 | 2 mg | 40 units | Once weekly | First escalation. Monitor for GI side effects. |
| 9-12 | 4 mg | 80 units | Once weekly | Appetite suppression typically becomes more pronounced. |
| 13-20 | 8 mg | 160 units | Once weekly | Significant weight loss phase. Stay here if side effects are manageable. |
| 21-24 | 12 mg | 240 units | Once weekly | Maximum dose. Triple-agonist activity at full strength. |
1-4: 1 mg
Starting dose. Nausea and decreased appetite are expected.
5-8: 2 mg
First escalation. Monitor for GI side effects.
9-12: 4 mg
Appetite suppression typically becomes more pronounced.
13-20: 8 mg
Significant weight loss phase. Stay here if side effects are manageable.
21-24: 12 mg
Maximum dose. Triple-agonist activity at full strength.
What you need for a 24-week Retatrutide protocol
Retatrutide vials (10 mg each)
Quantity: 14
Bacteriostatic water (30 mL vial)
Quantity: 1
Insulin syringes (U-100, 29ga)
Quantity: 24+ (one per injection, never reuse)
Alcohol prep pads
Quantity: 48+ (one for vial, one for skin)
Sharps container
Quantity: 1
Quantities based on 24-week protocol using 10 mg vials reconstituted with 2 mL BAC water each.
How to mix your Retatrutide
Your concentration:
10 mg peptide + 2 mL water = 5.00 mg/mL (5000 mcg/mL)
- 1
Wash your hands
Wash with soap and water for 30 seconds. Dry completely.
- 2
Clean the vial tops
Wipe the rubber stopper on your Retatrutide vial AND your bacteriostatic water vial with an alcohol swab. Let air dry for 10 seconds.
- 3
Draw 2 mL of bacteriostatic water
Using an insulin syringe, draw 2 mL (200 units on a U-100 syringe) of bacteriostatic water.
- 4
Inject water into the Retatrutide vial
Hold the peptide vial at a 45-degree angle. Point the needle at the WALL of the vial, NOT directly onto the powder. Push the plunger slowly over 10-15 seconds. Let the water run down the inside wall.
- 5
Swirl gently to dissolve
Swirl the vial in a slow circular motion for 30-60 seconds. NEVER shake. If not fully dissolved, let it sit for 2-5 minutes and swirl again.
- 6
Refrigerate immediately
Store reconstituted peptide at 36-46 degrees F (2-8 degrees C). Good for 4-6 weeks refrigerated. Label the vial with the date you mixed it.
Common mistakes that ruin your peptide:
- Shaking the vial (breaks peptide bonds, reduces potency 30-50%)
- Spraying water directly on the powder (damages the peptide)
- Using sterile water instead of bacteriostatic water (no preservative, short shelf life)
- Leaving mixed peptide at room temperature (loses 10-20% potency per day)
How to inject Retatrutide
Timing: Same day each week, any time of day
- 1Choose your injection site and rotate each time (at least 1 inch from the last site).
- 2Wipe the injection site with an alcohol prep pad. Let air dry completely.
- 3Draw your dose (check the dosing schedule above for exact syringe units).
- 4Pinch a fold of skin at the injection site.
- 5Insert the needle at a 45-90 degree angle into the pinched skin fold.
- 6Push the plunger slowly and steadily.
- 7Release the skin fold, then withdraw the needle.
- 8Do NOT rub the injection site. Light pressure with a cotton ball is fine if there is any blood.
- 9Dispose of the syringe immediately in your sharps container. Never recap or reuse.
Site rotation tip
Divide your preferred injection area into a mental grid. Move to a new spot each injection. For Abdomen and Thigh and Upper arm injections, alternate between sides (left/right) each time.
Research references
- LY3437943, a novel triple GIP, GLP-1, and glucagon receptor agonist in people with type 2 diabetes: a phase 1b, multicentre, double-blind, placebo-controlled, randomised, multiple-ascending dose trial — The Lancet (2022) [PubMed]
- Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial — New England Journal of Medicine (2023) [PubMed]
- Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA — The Lancet (2023) [PubMed]
- Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial — Nature Medicine (2024) [PubMed]
- Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial — The Lancet Diabetes & Endocrinology (2025) [PubMed]
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials — Diabetes, Obesity and Metabolism (2026) [PubMed]
- Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist for obesity treatment: a systematic review and meta-analysis of randomized controlled trials — Proceedings of Baylor University Medical Center (2025) [PubMed]
- Efficacy and safety of triple hormone receptor agonist retatrutide for the management of obesity: a systematic review and meta-analysis — Expert Review of Clinical Pharmacology (2025) [PubMed]
- Effects of once-weekly subcutaneous retatrutide on weight and metabolic markers: A systematic review and meta-analysis of randomized controlled trials — Metabolism Open (2024) [PubMed]
- Retatrutide showing promise in obesity (and type 2 diabetes) — Expert Opinion on Investigational Drugs (2023) [PubMed]
- Retatrutide: a triple incretin receptor agonist for obesity management — Expert Opinion on Investigational Drugs (2023) [PubMed]
- A review of an investigational drug retatrutide, a novel triple agonist agent for the treatment of obesity — European Journal of Clinical Pharmacology (2024) [PubMed]
- Incretin triple agonist retatrutide (LY3437943) alleviates obesity-associated cancer progression — NPJ Metabolic Health and Disease (2025) [PubMed]
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