How to Reconstitute a Peptide (Step by Step)

Your peptide shows up as a tiny puck or dusting of white powder at the bottom of a small glass vial. That's the peptide freeze-dried (the technical word is lyophilized) so it stays stable in shipping and storage. It's not usable like that — you have to turn it back into a liquid you can draw into a syringe. That step is called reconstitution, and it's genuinely simple once you've done it once.

What reconstitution actually is

You're adding sterile liquid — bacteriostatic water — to the powder so it dissolves into a clear solution. That solution is what you inject. Nothing about the peptide changes; you're just rehydrating it.

(If you haven't yet, read the water article first — bacteriostatic water is what lets the mixed vial stay good for weeks.)

The one piece of math: concentration

This is the only number that matters, and it's easy:

Concentration = milligrams of peptide ÷ milliliters of water you add.

Example: a 10 mg vial + 2 mL of bacteriostatic water = 5 mg/mL. Add 1 mL instead and you'd get 10 mg/mL (stronger, smaller draws); add 3 mL and you'd get ~3.3 mg/mL (weaker, bigger draws).

There's no single "right" amount of water — it just sets how concentrated your solution is, which changes how many units you draw per dose. Easy round numbers (1, 2, or 3 mL) make the syringe math clean. To see exactly how your choice translates into units, drop your numbers into the reconstitution & dosing calculator — it does the unit conversion for you.

Step by step

1. Let both vials reach room temperature and wash your hands. Swab the rubber stopper of the peptide vial and the bacteriostatic water vial with alcohol.
2. Draw your chosen volume of bacteriostatic water (e.g., 2 mL) into a syringe.
3. Add the water SLOWLY, aimed down the inside glass wall of the vial — not blasted straight onto the powder. Letting it run down the side is gentle on the peptide.
4. Don't shake it. Set it down and let the powder dissolve, or swirl gently if needed. Shaking shears delicate peptide chains and can degrade them — swirl, never shake.
5. Look at it. A properly mixed vial is clear. If it's cloudy, discolored, or has floating particles that won't dissolve, don't use it.
6. Refrigerate it. Store the reconstituted vial in the fridge (not the freezer unless told otherwise), upright, away from light, and minimize warm/cold cycles.

How long it lasts

Once mixed and refrigerated, a reconstituted peptide is generally good for about 28 days — the same window the benzyl alcohol in bacteriostatic water protects. Some compounds are more or less stable than others, but ~4 weeks is the sensible default. Label the vial with the date you mixed it.

What's next

Reconstituting gives you a vial of liquid. Two things follow: figuring out the exact units to draw for your dose (that's the dosing calculator), and the actual injection — how and where.

Educational information only — not medical advice. Many peptides are sold for research use only and are not FDA-approved for human use. The "swirl, don't shake" and "down the vial wall" guidance is standard practical technique echoed across peptide educators; the ~28-day refrigerated window is a general default, not a per-compound guarantee.

Sources: BAC Water for Peptides — freemedicaljournals.com (/blog/bac-water-for-peptides/); OHM reconstitution math (concentration = mg ÷ mL), consistent with the site's reconstitution & dosing calculator.