How to Reconstitute Retatrutide: Step-by-Step
Investigational drug. Retatrutide is not FDA approved and is sold only as a research chemical outside clinical trials. This page explains the reconstitution mechanics people ask about; it is not medical advice or an endorsement of self-administering an unapproved drug. See our retatrutide FDA status guide.
Retatrutide ships as a freeze-dried (lyophilized) powder that has to be mixed with liquid before any dose can be measured. The step that trips people up is not the mixing itself; it is the math. The amount of water you add sets the concentration, and the concentration decides how many units on an insulin syringe equal your target dose. Get that wrong and the dose is wrong. This guide walks the process, gives a live calculator, and shows the units math.
What You Need
Reconstitution needs the vial of lyophilized retatrutide, a vial of bacteriostatic water (preferred over sterile water because its preservative allows repeat needle entries), alcohol wipes, a larger syringe to transfer the water, and U-100 insulin syringes to draw doses. The same supplies and technique apply to any peptide; our general reconstitution guide covers the fundamentals.
Step-by-Step: Reconstituting Retatrutide
Decide your target concentration first, then work backward to the water volume. The steps:
- Wipe the stopper of both the retatrutide vial and the bacteriostatic water vial with an alcohol swab.
- Draw your chosen volume of bacteriostatic water into a transfer syringe (see the concentration table below).
- Insert the needle into the retatrutide vial and inject the water slowly down the inside glass wall, not directly onto the powder.
- Let the powder dissolve on its own, or swirl gently. Do not shake, which foams and can degrade the peptide.
- Once the liquid is clear with no particles, it is reconstituted. Label the vial with the date and concentration.
- Refrigerate and draw individual doses with a fresh U-100 insulin syringe.
Retatrutide Reconstitution Calculator
Set the vial size, the water volume, and your target dose. The calculator returns the concentration and the exact number of units to draw on a U-100 insulin syringe.
Peptide Reconstitution Calculator
Calculate concentrations and dosing volumes for peptide reconstitution
Calculation Results
Concentration
25.00
mcg per unit
Volume to Draw
10.0
units per dose
Doses per Vial
20.0
total doses
Vial Duration
20
days
Syringe Fill Indicator
Vial Label Generator
Retatrutide
25.00 mcg/unit
Reconstituted: 2026-07-18
Expires: 2026-08-15
Disclaimer: This calculator is for research and educational purposes only. It is not medical advice. Always consult with a healthcare professional before using any peptide product. Verify all calculations independently.
Concentration and Units Reference
On a standard U-100 insulin syringe, one unit is 0.01 mL, so 100 units equals 1 mL. The formula is units = (dose in mg / concentration in mg per mL) x 100. The table shows common setups for a 10 mg vial.
| Vial | BAC Water | Concentration | 2 mg dose | 4 mg dose |
|---|---|---|---|---|
| 10 mg | 1 mL | 10 mg/mL | 20 units | 40 units |
| 10 mg | 2 mL | 5 mg/mL | 40 units | 80 units |
For the full dosing ladder these amounts map to, see the retatrutide dosage chart and the retatrutide dosage calculator.
How to Inject Retatrutide
Retatrutide is given subcutaneously, into the fat just under the skin. The usual sites are the abdomen (staying about two inches clear of the navel), the outer thigh, and the back of the upper arm. Pinch the skin, insert a short insulin needle at 45 to 90 degrees, and inject slowly. Rotate sites each week to avoid lumps and irritation. The technique is identical to other GLP-1 injections; our how to inject peptides and peptide injection sites guides go deeper.
Storage After Reconstitution
Before mixing, lyophilized powder is stable and tolerates room temperature for shipping, though long-term it belongs in the freezer or fridge. Once reconstituted, keep it refrigerated at 36 to 46 F (2 to 8 C) and use it within about four weeks. Discard any solution that turns cloudy, discolors, or shows floating particles. More detail is in our peptide storage guide.
Common Mistakes That Cause Wrong Doses
The two biggest errors are shaking the vial (which foams and can degrade the peptide) and confusing milligrams with units. A third is forgetting that the water volume, not the vial size, sets concentration, so two people with identical vials can need different unit counts for the same dose. Because retatrutide is a research chemical, the stated vial strength is also unverified, which adds uncertainty that a prescribed, labeled drug would not have. Review side effects that scale with dose in our retatrutide side effects guide.
Related Guides
Frequently Asked Questions About Retatrutide
There is no single correct amount; the volume you add sets the concentration. A common choice is to add 1 mL of bacteriostatic water to a 10 mg vial, giving 10 mg/mL, where 20 units on a U-100 insulin syringe equals a 2 mg dose. Adding 2 mL to the same vial gives 5 mg/mL, so the same 2 mg dose becomes 40 units. Pick a volume that makes your target dose land on an easy-to-read number of units, then use the calculator on this page to confirm.
Wipe both vial stoppers with alcohol, draw your chosen volume of bacteriostatic water into a syringe, and inject it slowly down the inside wall of the retatrutide vial rather than blasting it onto the powder. Let it dissolve on its own or swirl gently. Never shake. Once the solution is clear, it is ready to draw. Label the vial with the date and concentration, and refrigerate it.
It depends on concentration. At 10 mg/mL (10 mg vial in 1 mL water), 2 mg is 20 units on a U-100 syringe. At 5 mg/mL (10 mg vial in 2 mL water), 2 mg is 40 units. The rule: units = (dose in mg / concentration in mg per mL) x 100. The calculator on this page does this for any vial and water volume.
Retatrutide is a subcutaneous injection, given into the fat under the skin of the abdomen (avoiding a two-inch circle around the navel), the outer thigh, or the back of the upper arm. Pinch the skin, insert a short insulin needle at 45 to 90 degrees, inject slowly, and rotate sites week to week to avoid lumps. This is the same technique used for semaglutide and tirzepatide.
Once mixed, keep it refrigerated at 36 to 46 F (2 to 8 C). Reconstituted peptide made with bacteriostatic water is generally used within about four weeks; the benzyl alcohol preservative in bacteriostatic water is what allows repeat needle entries. Sterile water has no preservative and should be used much sooner. Discard if the solution turns cloudy, discolored, or shows particles.
No. Shaking foams the solution and can damage the peptide. Add the water gently down the vial wall and let it dissolve, swirling lightly if needed. Foaming also makes it hard to draw an accurate dose because bubbles displace liquid in the syringe.
Retatrutide is not FDA approved as of mid-2026; it remains investigational and is sold only as a research chemical outside clinical trials. That means there is no approved label, no verified concentration, and no clinician confirming purity or sterility. This page explains the mechanics people ask about; it is not medical advice or an endorsement of self-administering an unapproved drug.