How to reconstitute tirzepatide

Tirzepatide is available in multiple forms. Mounjaro and Zepbound are FDA-approved pre-filled pens containing liquid tirzepatide at fixed concentrations. These pens do not require reconstitution. You use them as directed with the pen's built-in mechanism.

Compounded tirzepatide vials, on the other hand, typically contain lyophilized (freeze-dried) powder that must be reconstituted with bacteriostatic water or another specified diluent. The vial label should state the tirzepatide amount (e.g., 10 mg, 30 mg, 60 mg) and the instructions for mixing.

Before looking for a reconstitution recipe, confirm which product form you have. A pen does not need water. A vial does.

FDA has issued warnings about unapproved medications marketed for diabetes or weight loss, including products containing semaglutide or tirzepatide that are not FDA-approved. These warnings cite potential safety risks from products not subject to FDA review for safety, effectiveness, and manufacturing quality. Read the FDA safety information.

Compounded tirzepatide from a 503A or 503B pharmacy is prepared under different regulatory conditions than FDA-approved products. The instructions, storage, beyond-use dating, and safety profile may differ. This guide does not determine whether a compounded product is appropriate for you.

If you have questions about a compounded tirzepatide product, direct them to the dispensing pharmacy or prescriber.

Vial amount

Copy the tirzepatide amount printed on the vial: 10 mg, 30 mg, 60 mg, or another value. This is the numerator for concentration.

Diluent type

Record the named diluent: bacteriostatic water, sterile water, or other. Do not assume BAC water unless instructions specify it.

Liquid volume

Copy the instructed final volume in milliliters. This is the denominator for concentration.

Storage and BUD

Keep the storage conditions and beyond-use date from your pharmacy label. The water label does not set the mixed tirzepatide's discard date.

Open questions

Save the pharmacy or prescriber contact for any unclear diluent, volume, storage, or dosing questions.

Divide the vial amount by the final liquid volume to get concentration. Then divide the target amount by that concentration to get the draw volume. A U-100 syringe conversion applies only when the physical syringe is U-100.

Worked examples (arithmetic only, not recommendations):

10 mg ÷ 1 mL

= 10 mg/mL. For 2.5 mg: 2.5 ÷ 10 = 0.25 mL = 25 units (U-100).

30 mg ÷ 3 mL

= 10 mg/mL. For 5 mg: 5 ÷ 10 = 0.5 mL = 50 units (U-100).

60 mg ÷ 6 mL

= 10 mg/mL. For 10 mg: 10 ÷ 10 = 1 mL = 100 units (U-100).

The tirzepatide reconstitution calculator lets you enter confirmed values and review concentration, milliliters, and U-100 units together. It does not choose the values.

Clean the vial stopper with an alcohol swab. Draw the confirmed volume of diluent into a syringe, insert the needle through the stopper, and inject slowly against the inside wall of the vial. Direct impact on the lyophilized powder can damage the peptide or cause excessive foaming.

Once the liquid is added, gently swirl or roll the vial until the powder fully dissolves. Do not shake vigorously. A clear solution without visible particles is the typical target.

Label the vial with the concentration (e.g., 10 mg/mL), the date mixed, and the discard date from your pharmacy label. Follow CDC injection-safety guidance for aseptic technique. Read the CDC guidance.

After reconstitution, tirzepatide requires refrigeration. The storage conditions and beyond-use date come from the pharmacy label, not from the bacteriostatic water. A 28-day water limit does not mean mixed tirzepatide lasts 28 days.

For compounded products, the dispensing pharmacy assigns a beyond-use date based on stability data and USP guidelines. Follow that date, not a forum estimate. If no date is provided, ask the pharmacy before the first use.

For more on storage timing, see the reconstituted peptide fridge life guide and the peptide storage and travel guide.