Find the medicine name first
Find the active medicine named on the prescription label, such as semaglutide or tirzepatide. Keep its name beside its strength when you write the details down. An FDA alert about semaglutide in the US describes varying concentrations and confusion between mg, mL and syringe units.1
Keep the prescription label and its instructions together. If a name, number or instruction is missing or hard to read, your prescriber or care team can clarify it against your prescription.
Read the mg and mL together
mg describes an amount of medicine. mL describes a volume of liquid. A concentration connects them: 10 mg / 2 mL means 10 mg in each 2 mL, equivalent to 5 mg/mL. It is a different concentration from 10 mg/mL. These are invented label examples, not amounts to take.
The volume after the slash is part of that ratio. It does not, on its own, tell you the container's total fill. Look for a separate total-volume or quantity field. If the label says mg per 0.5 mL, keep the 0.5 mL when copying it; changing it to 1 mL changes the meaning.
Keep each ingredient with its own number
A label may name more than one ingredient. The FDA's US alert also discusses ingredients added to semaglutide, including vitamin B12.1 Two ingredient names and two strengths need to be read as separate entries. Adding the strengths together would not give the concentration of either ingredient.
If slashes or line breaks make the order unclear, ask your prescriber or care team to write out each ingredient and its mg/mL separately. A calculator needs the concentration of the medicine you selected, not a combined number for the mixture.
Syringe units describe a different scale
On a U-100 syringe, 100 units corresponds to 1 mL, so 25 units corresponds to 0.25 mL.1 That volume does not have one fixed mg value: the mg depends on the concentration. This volume relationship applies to a U-100 scale, not pen clicks or every syringe.
The units and mg calculator shows the arithmetic from the concentration and amount you enter. The label quiz lets you practise with fictional labels. Neither selects a dose or confirms what is inside a vial.
Read the details back to your prescriber or care team
A useful question for your prescriber or care team is: “Can you confirm the medicine name, its concentration in mg/mL, the total liquid volume and how my prescribed amount is measured with this syringe?” The FDA encourages patients to ask their provider about measuring the intended amount.1
Once those details are clear, keep your record in Onederland's dose tracker: medicine, amount, date, injection site and notes in one place. You can look back at what you logged when you have a question for your care team.
