Not an approved product“Compounded drugs are not approved by FDA,” and the FDA says unapproved versions are not reviewed for safety, effectiveness or quality.[3][4] Your dose is the one written by your prescriber and printed on your pharmacy label. This page only converts it.
What is the starting dose of compounded tirzepatide?
No FDA document sets a starting dose for compounded tirzepatide; the only official starting dose is the one in the approved labels, 2.5 mg once weekly for 4 weeks.[1][2] The Zepbound label adds that “the 2.5 mg dosage is for treatment initiation and is not approved as a maintenance dosage.”[1] The slow start is there because stomach side effects are most common while the dose is going up.[1] Whether a compounded product is started the same way is a prescriber's decision, not something a calculator or a pharmacy website can settle.
Compounded tirzepatide dosage in units
A compounded dose in units is the dose in mg divided by the vial's mg per mL, times 100 on a U-100 insulin syringe. The catch is reading the label: some state the strength per mL, others the total in the vial.
| Label says | Means | mg/mL | 2.5 mg | 5 mg | 7.5 mg |
|---|---|---|---|---|---|
| 10 mg/mL | strength per mL | 10 | 25 | 50 | 75 |
| 20 mg/2 mL | total in the vial: same 10 mg/mL | 10 | 25 | 50 | 75 |
| 27 mg/3 mL | total in the vial: 9 mg/mL | 9 | 27.8 | 55.6 | 83.3 |
| 5 mg/mL | strength per mL | 5 | 50 | 100 | >100 |
| 30 mg/1.5 mL | total in the vial: 20 mg/mL | 20 | 12.5 | 25 | 37.5 |
The 27 mg/3 mL row is a real format: the FDA's April 2026 warning letter to the outsourcing facility ProRx describes 27 mg/3 mL multi-dose tirzepatide vials, which had been recalled for lack of sterility assurance.[6] At 9 mg/mL, 2.5 mg is 27.8 units, a value that falls between the 2-unit marks of a 1 mL syringe. The calculator above shows the nearest mark.
Compounded tirzepatide maintenance dose
The only maintenance doses the FDA has evaluated are those in the approved labels: 5, 10 or 15 mg weekly for weight (Zepbound), 10 or 15 mg for sleep apnea, and whatever level controls blood sugar for Mounjaro, never above 15 mg.[1][2] The steps between them are 2.5 mg, at least 4 weeks apart. A compounded product has no labeled maintenance dose of its own. The full schedule is on the tirzepatide dosage chart.
Five checks before measuring a compounded dose
Most dosing mistakes with compounded vials come from five steps: reading the strength, converting, matching the syringe, tiny volumes and switching vials.
- Find the mg/mL. Divide a total ("20 mg/2 mL") by its volume. If the label gives neither, ask the pharmacy; no calculation is possible.
- Convert once, write it down. Units = mg ÷ mg/mL × 100. Keep the number with the vial.
- Match the syringe to the instructions. Units only apply to U-100 insulin syringes (100 units = 1 mL). A syringe marked in mL needs the mL figure instead.
- Watch tiny volumes. Below about 2 units, the width of a syringe line is a large share of the dose.
- Double-check any change of vial. A new vial with a different strength changes the units for the same mg dose.
The FDA has documented exactly these errors with compounded GLP-1 drugs: in a 2024 alert about compounded semaglutide it described “confusion between different units of measurement (e.g., milliliters, milligrams and ‘units’)”.[5]
How approved vials compare
FDA-approved tirzepatide vials avoid most of this arithmetic: a single-dose vial is always 0.5 mL (50 units on a U-100 scale) and a multi-dose vial dose is always 0.6 mL (60 units), whatever the strength.[1] See compounded tirzepatide vs Zepbound for the full comparison, and compounded tirzepatide for the FDA's position.
Related
- How many units is 2.5 mg?Every vial type, every dose
- Bac water calculatorFor powder that is mixed first
- Tirzepatide dosage in unitsTwo-way chart at every concentration
Frequently asked questions
What is the starting dose of compounded tirzepatide?
How many units is 2.5 mg of compounded tirzepatide?
It depends on the vial: 25 units at 10 mg/mL, 50 units at 5 mg/mL, 27.8 units at 9 mg/mL (a 27 mg/3 mL vial) and 12.5 units at 20 mg/mL.
What is the maximum compounded tirzepatide dose?
Is compounded tirzepatide dosed the same as Zepbound?
Sources
- Zepbound (tirzepatide) injection: prescribing information, Medication Guide and Instructions for Use
- Mounjaro (tirzepatide) injection: prescribing information and Instructions for Use
- FDA clarifies policies for compounders as national GLP-1 supply begins to stabilize
- FDA's concerns with unapproved GLP-1 drugs used for weight loss
- FDA alerts health care providers, compounders and patients of dosing errors associated with compounded injectable semaglutide products
- Warning letter: ProRx LLC