What is the starting dose of compounded tirzepatide?

There is no FDA-approved starting dose for a compounded product, because compounded tirzepatide is not FDA-approved and carries no FDA-reviewed label. The reference point a prescriber works from is the approved label's own starting dose — 2.5 mg injected subcutaneously once weekly for four weeks, an initiation dose only, not a maintenance dose. What that 2.5 mg comes out to in a specific compounded vial depends on that vial's own concentration, not a number the label sets.

Off the FDA label · Checked live August 2026

Tirzepatide dosage chart: from the label to your vial

The FDA-approved starting dose of tirzepatide is 2.5 mg injected subcutaneously once weekly, for four weeks. That number is on both the Zepbound and Mounjaro labels, and both state plainly that 2.5 mg is for treatment initiation only — not a maintenance dose. There is no separate FDA-approved starting dose for a compounded product, because a compounded vial carries no FDA-reviewed label of its own; the 2.5 mg figure is the reference point a prescriber is working from, not a rule the vial itself states. What that 2.5 mg means in mL or syringe units depends entirely on that specific vial's concentration — the chart below.

This page states what the label specifies. It does not recommend a dose, and it does not convert a compounded vial into “your” dose — that number comes from a prescriber. For the full evidence discussion, trial data and a four-question FAQ, see our complete tirzepatide dosing reference.

The label's ladder

Every step requires at least four weeks on the current dose before increasing — the label's stated reason is to reduce the risk of gastrointestinal adverse reactions.

When	Dose	Note
Weeks 1–4	2.5 mg once weekly	Initiation only — not approved as a maintenance dose
Week 5	5 mg once weekly	Lowest approved maintenance dose
Every ≥4 weeks after	+2.5 mg per step	7.5 → 10 → 12.5 → 15 mg, as tolerated
Maintenance	5, 10 or 15 mg	Weight reduction. OSA: 10 or 15 mg. Max: 15 mg (10 mg pediatric, Mounjaro)

Read directly off Zepbound's and Mounjaro's §2.1–2.2. The label also says a lower maintenance dose is a valid option for anyone who does not tolerate a higher one — the ladder runs both ways, not only up.

Missed dose or changed injection day

A missed dose can be given as soon as possible within 4 days (96 hours). Past that window, the label says to skip it and resume on the normal weekly day. The injection day itself can move, as long as at least 3 days (72 hours) separate the two doses.

These windows are specific to tirzepatide — semaglutide's labels use different numbers. See the semaglutide dosage chart before assuming the rule carries across molecules.

Milligrams on the label, milliliters in the syringe

The approved pens hide this arithmetic by raising the concentration in step with the dose, so the injected volume stays a fixed 0.6 mL at every rung. A compounded vial has one concentration for its whole life, so the volume — and the units reading — changes at every step. The last column below is plain arithmetic (dose ÷ concentration) at one hypothetical fixed concentration, shown only to make the pattern visible; it is not a dose for anyone, and the only concentration that matters is the one printed on the vial in front of you.

Dose	Approved vial concentration	Volume from approved vial	Volume at one 25 mg/mL vial
2.5 mg	4.17 mg/mL	0.6 mL / 60 units	0.1 mL / 10 units
5 mg	8.33 mg/mL	0.6 mL / 60 units	0.2 mL / 20 units
7.5 mg	12.5 mg/mL	0.6 mL / 60 units	0.3 mL / 30 units
10 mg	16.7 mg/mL	0.6 mL / 60 units	0.4 mL / 40 units
12.5 mg	20.8 mg/mL	0.6 mL / 60 units	0.5 mL / 50 units
15 mg	25 mg/mL	0.6 mL / 60 units	0.6 mL / 60 units

The rule behind every column on the right: volume (mL) = dose (mg) ÷ concentration (mg/mL), and on a U-100 insulin syringe, units = mL × 100. Run that arithmetic on your own vial's printed concentration — not a number copied from a forum post about a different vial — with our tirzepatide reconstitution calculator. Given a units reading and want the mg it represents instead? Our units-to-mg converter runs the same math in the other direction.

FDA has reported adverse events, some requiring hospitalization, in patients “prescribed compounded semaglutide or tirzepatide products in doses beyond what is in the FDA-approved drug label,” including errors in titration schedule and dose amount. Source below.

Sources, checked live

All three confirmed live and current on August 2026. Labels change; verify the current version before relying on a printed copy.

Keep reading

Medical disclaimer: This content is for general educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a licensed healthcare professional before starting, stopping, or changing any treatment.