How this works
The math
How the arithmetic works
strength in mg/mL = powder in mg ÷ liquid in mLmL for a dose = dose in mg ÷ strength in mg/mLunits = mL × 100 (U-100 only)For example, 20 mg with 2 mL added is 10 mg/mL, and a 5 mg dose at that strength is 0.5 mL, or 50 units. The same 5 mg at 5 mg/mL is 100 units, which is why the strength has to be right before anything else.
This assumes the powder adds no volume to the liquid. That isn’t always true, and only your pharmacist can say for your vial.
What the label shows
- Compounded powder
- FDA says compounded drugs “pose a higher risk” than approved ones, and should only be used for patients whose medical needs can’t be met by an available FDA-approved drug.6
- Vials sold “for research”
- FDA says these are illegally sold, unapproved and of unknown quality, and urges people not to buy them.1
- Salt forms
- FDA says semaglutide sodium and semaglutide acetate are different active ingredients from the approved medicines, and that it isn’t aware of a lawful basis for compounding with them.1
- After first use
- For compounded multiple-dose vials, FDA says to discard within 28 days after first use, and to use a new, sterile needle and syringe for each dose.1
- This page
- It does arithmetic. It doesn’t teach mixing, and it can’t tell you whether a powder is sterile, what strength it really is or whether you should use it.
- Dates do not establish usability
- An earlier printed expiry or beyond-use date, storage conditions and the vial’s own instructions can shorten a deadline. This arithmetic cannot establish that a vial can be used. Check with your pharmacist first.
- Four weekly doses
- The count uses days 0, 7, 14 and 21, and excludes a fifth dose on day 28. Discard on day 28 at the latest, or an earlier applicable deadline.
Before you act on this
The FDA reports include people who meant to draw 5 units and drew 50, and one who searched online for advice and took five times their dose.6 Say your number out loud and look at the syringe before you inject.
Took more than you were prescribed? Call your prescriber or pharmacist now. In the US, Poison Help is 1-800-222-1222. Severe vomiting, severe nausea or signs of low blood sugar need urgent care.
Something went wrong, or a vial looks or acts wrong? Tell your prescriber. In the US, you can also report it to FDA’s MedWatch program.1
Always follow your doctor’s or prescriber’s advice and guidance. Talk to your prescriber before changing your dose.
Read this first
No FDA-approved GLP-1 comes as a powder you mix
- Zepbound, Mounjaro, Wegovy and Ozempic injections come as ready-made solutions, and none of their labels describes mixing.2345 FDA says compounded drugs aren’t FDA approved, and that it doesn’t review them for safety, effectiveness or quality before they’re sold.1
- If your vial says “for research purposes” or “not for human consumption”: FDA says these products are sold illegally, are of unknown quality and may be harmful, and it urges people not to buy them.1 No arithmetic can tell you what’s in a vial.
- A wrong strength makes every dose from that vial wrong. FDA has adverse event reports, some needing hospital care, that may be related to dosing errors with compounded semaglutide. Most described people drawing too much from a vial, five to 20 times more than the intended dose.6
For information only, not medical advice. Verify results with your healthcare provider; Onederland accepts no liability for use of these tools.
- Runs on this device. Nothing you type is sent anywhere.
- Every figure names its source, below.
- Education, not medical advice. Your prescriber comes first.
Sources
Sources
- FDA: concerns with unapproved GLP-1 medicines, October 1, 2026. fda.gov
- Zepbound (tirzepatide) injection, US prescribing information, revised 08/2026. accessdata.fda.gov
- Mounjaro (tirzepatide) injection, US prescribing information, revised 08/2026. accessdata.fda.gov
- Wegovy (semaglutide) injection and tablets, US prescribing information, revised 06/2026. accessdata.fda.gov
- Ozempic (semaglutide) injection, US prescribing information, revised 05/2026. accessdata.fda.gov
- FDA: dosing errors with compounded injectable semaglutide, July 26, 2024. fda.gov
Label sources last checked on October 30, 2026. Onederland summarizes them; your prescriber and the full prescribing information come first.
