Tirzepatide Dosage Guide: Mounjaro/Zepbound Titration, Reconstitution and Safety

Tirzepatide is a once-weekly injectable peptide that activates both the GIP and GLP-1 receptors, distinguishing it from single-target GLP-1 drugs such as semaglutide. It is sold under two FDA-approved brand names built from the same molecule and the same titration ladder: Mounjaro for type 2 diabetes and Zepbound for chronic weight management and obstructive sleep apnea in adults with obesity. It carries a boxed warning for thyroid C-cell tumors based on rodent findings. Research-labeled lyophilized vials sold outside the pharmacy supply chain are a separate, non-FDA-regulated product using the same molecule name.

The supplied source reports the FDA-labeled titration ladder of 2.5, 5, 7.5, 10, 12.5, and 15 mg once weekly, holding each step at least 4 weeks, and states that 5, 10, and 15 mg are the approved maintenance doses while 2.5, 7.5, and 12.5 mg are transitional steps. It also reports research-vial mg-to-unit math using a 40 mg vial reconstituted with 2.0 mL bacteriostatic water for 20 mg/mL, and the labeled missed-dose rule of administering within 4 days (96 hours) or otherwise skipping to the next scheduled day.

This ladder is identical for Mounjaro and Zepbound; only the FDA-approved indication on the label differs. Not everyone needs to escalate to 15 mg; 5 mg and 10 mg are also approved maintenance doses with strong trial-reported effects. Research-vial titration using the same ladder is not itself FDA reviewed, even though the ladder is copied from the approved label.

Neutral research-material planning only. This does not establish an appropriate amount or route.

Routes and amounts are not interchangeable unless a verified study explicitly establishes a conversion.

Published study values describe those studies. Community-reported values are not validated dosing recommendations.

Concentration: 5 mg/mL

1. 1.This step applies to research-labeled vials only; FDA-approved pens and pre-filled vials do not require reconstitution.
2. 2.Confirm the exact quantity printed on the vial, commonly 40 mg.
3. 3.Choose and record the bacteriostatic water volume. 40 mg into 2.0 mL gives 20 mg/mL.
4. 4.Clean the vial stopper with an alcohol swab.
5. 5.Add the liquid slowly down the vial wall.
6. 6.Swirl gently until clear; do not shake.
7. 7.Inspect for cloudiness, discoloration, or particles and discard anything that is not clear.
8. 8.Label the vial with the calculated concentration and preparation date, and refrigerate; the reconstituted solution is commonly reported to keep for about 28 days refrigerated.

Reconstitution does not establish identity, purity, sterility, stability, or an appropriate amount.

• SURMOUNT-1 (Jastreboff et al., NEJM 2022) reported average weight loss of about 16.0% at 5 mg, 21.4% at 10 mg, and 22.5% at 15 mg over 72 weeks in adults with obesity without diabetes.
• The SURPASS trial program established glycemic efficacy and the approved titration ladder in adults with type 2 diabetes, supporting Mounjaro's May 2022 FDA approval.
• Zepbound's November 2023 FDA approval for chronic weight management was based on the SURMOUNT program, with a subsequent approval for obstructive sleep apnea in adults with obesity.
• Across the SURPASS and SURMOUNT programs, gastrointestinal effects such as nausea, diarrhea, and constipation were the most commonly reported adverse events, generally most pronounced during dose escalation.

This is an evidence-gap and precaution list, not an approved prescribing label.