Compounded tirzepatide dosing
How doses are usually stepped, how to turn a dose into units for your vial, and the dosing errors FDA has seen.
Key facts
- Compounded tirzepatide is not FDA-approved; FDA does not review compounded drugs for safety, effectiveness or quality before they are sold.
- Prescribers usually follow the approved schedule: 2.5 mg weekly, rising 2.5 mg at least every 4 weeks, up to 15 mg.
- The units depend on your vial’s concentration: 5 mg is 50 units at 10 mg/mL, 25 units at 20 mg/mL.
- FDA has received reports of dosing errors, and of doses above or faster than the approved label.
What compounded tirzepatide is
A pharmacy prepares it for a named patient on a prescription, usually as a liquid in a vial at a concentration the pharmacy chooses. It contains the same molecule as Zepbound and Mounjaro but is not the approved product, and some preparations add other ingredients. FDA states that it does not review compounded drugs for safety, effectiveness or quality before they are marketed1.
The dosing schedule
There is no label for a compounded product. Prescribers generally follow the approved one:
| Step | Weekly dose | When |
|---|---|---|
| Start | 2.5 mg | weeks 1–4 |
| Step 2 | 5 mg | after at least 4 weeks on the previous dose |
| Step 3 | 7.5 mg | after at least 4 weeks on the previous dose |
| Step 4 | 10 mg | after at least 4 weeks on the previous dose |
| Step 5 | 12.5 mg | after at least 4 weeks on the previous dose |
| Maximum | 15 mg | after at least 4 weeks on the previous dose |
Compounded tirzepatide in units
| Dose | 5 mg/mL | 10 mg/mL | 20 mg/mL |
|---|---|---|---|
| 2.5 mg | 50 units | 25 units | 12.5 units |
| 5 mg | 100 units | 50 units | 25 units |
| 7.5 mg | over 1 mL | 75 units | 37.5 units |
| 10 mg | over 1 mL | 100 units | 50 units |
| 12.5 mg | over 1 mL | over 1 mL | 62.5 units |
| 15 mg | over 1 mL | over 1 mL | 75 units |
Example concentrations. See the full units chart for ten concentrations.
Work out your draw
Filled from the calculator. Add your next step and print. Nothing is sent or stored.
What else is in the vial
Zepbound contains tirzepatide with sodium chloride and sodium phosphate; the multi-dose vial and KwikPen add benzyl alcohol, glycerin and phenol2. Compounded preparations are often different: some add vitamin B12, niacinamide or glycine. In a warning letter of 18 September 2026 to Empower Pharmacy, FDA called added niacinamide and B12 “pretextual” differences from the approved drugs at the volumes produced3. No trial has tested whether these additions change how tirzepatide works or how stable it is.
Questions to ask the pharmacy
- What is the concentration, in mg/mL, and will it stay the same on refills?
- What else is in the vial besides tirzepatide?
- How should it be stored, and what is the beyond-use date once opened?
- Is it compounded by a 503A pharmacy for me, or a 503B outsourcing facility?
- Which syringe should I use, and how many units is my dose?
Side effects
There are no trial data on compounded tirzepatide. For the approved product, at fixed doses:
| Side effect | Placebo | 5 mg | 10 mg | 15 mg |
|---|---|---|---|---|
| Nausea | 8% | 25% | 29% | 28% |
| Diarrhoea | 8% | 19% | 21% | 23% |
| Vomiting | 2% | 8% | 11% | 13% |
| Constipation | 5% | 17% | 14% | 11% |
Who should not take tirzepatide
- A personal or family history of medullary thyroid carcinoma, or MEN 2: tirzepatide is contraindicated (boxed warning on thyroid C-cell tumours seen in rats).
- A serious allergic reaction to tirzepatide or any ingredient: contraindicated; anaphylaxis and angioedema have been reported.
- Pregnancy: stop when a pregnancy is recognised; weight loss offers no benefit and may harm the fetus.
- Severe gastroparesis: not recommended.
- Birth control pills: may work less well. Use a non-oral method, or add a barrier method, for 4 weeks after starting and after each dose increase.
- Insulin or sulfonylureas: raise the risk of low blood sugar, including severe episodes; their dose may need lowering.
- Other tirzepatide products or any GLP-1 medicine (Ozempic, Wegovy, Trulicity and others): not to be combined.
- Other medicines taken by mouth: tirzepatide slows stomach emptying, which can change how they are absorbed; medicines that need careful levels, such as warfarin, may need monitoring.
What FDA warns about
FDA also warns about products sold as “for research purposes” or “not for human consumption”: it describes companies selling tirzepatide that way directly to consumers, with dosing instructions, as illegally selling unapproved drugs1.
Getting tirzepatide prescribed
Frequently asked questions
What is the starting dose of compounded tirzepatide?
Prescribers usually start at 2.5 mg weekly for 4 weeks, as on the approved label, then step up by 2.5 mg.
How many units is 2.5 mg of compounded tirzepatide?
It depends on the concentration: 25 units at 10 mg/mL, 50 units at 5 mg/mL, 12.5 units at 20 mg/mL.
Is compounded tirzepatide FDA-approved?
No. FDA does not review compounded drugs for safety, effectiveness or quality before they are marketed.
Why do compounded doses differ between pharmacies?
Each pharmacy chooses its concentration and some add ingredients, so the same milligram dose can be a different number of units.
Scientific references
- U.S. Food and Drug Administration. FDA's concerns with unapproved GLP-1 drugs used for weight loss. Content current as of 1 Oct 2026.
- Eli Lilly and Company. ZEPBOUND (tirzepatide) prescribing information. DailyMed, 2026.
- U.S. Food and Drug Administration. Warning letter to Empower Clinic Services LLC dba Empower Pharmacy, 738238, 18 Sep 2026.