Reading medicine names and labels
How to read medicine strength: mg, mcg, mg/mL, %
The strength on a pack tells you how much active ingredient is in each unit or in a set amount of liquid, cream or powder. This guide explains the units you will see, so you can match a pack to the right registry entry.
What "strength" means
Strength is the amount of active ingredient in the product. For a tablet or capsule it is usually the amount in one piece. For a liquid, cream or injection it is usually the amount in a given volume or weight. Strength describes the product. It is not an instruction about how much to take.
Units of weight: mg, mcg, gm
- mg: milligram, one thousandth of a gram. "500 mg" means 500 milligrams of active ingredient.
- mcg (also written µg): microgram, one thousandth of a milligram. 1 mg = 1,000 mcg.
- g or gm: gram. 1 g = 1,000 mg. The DGDA registry often writes grams as "gm".
Because these units differ by a factor of a thousand, the unit matters as much as the number. 250 mcg and 250 mg are very different amounts, so always read the unit as well as the figure.
Liquids: mg/mL and mg/5 mL
For syrups, suspensions, drops and many injections, strength is written as an amount per volume. mL means millilitre.
- mg/mL: milligrams in each millilitre of liquid. "80 mg/mL" means each 1 mL contains 80 mg.
- mg/5 mL: milligrams in every 5 mL. "120 mg/5 mL" means each 5 mL contains 120 mg; as arithmetic, that is the same concentration as 24 mg/mL.
- gm/100 mL or mg/vial: amount in a whole bottle, bag or vial, common for infusions and injections.
Two liquids of the same generic can have different concentrations, so check whether a label says per mL, per 5 mL or per bottle before comparing them.
Percentages: %
Creams, ointments, gels, eye drops and some solutions are often labelled with a percentage. A percentage is an amount per 100: 1% in a cream means 1 g of active ingredient in every 100 g of cream, which the registry sometimes writes as "1 gm/100 gm". For a solution it usually means grams per 100 mL. For example, the registry lists a 0.9% sodium chloride saline with a strength of 9 mg/mL: 0.9 g per 100 mL is 900 mg per 100 mL, which is 9 mg per mL.
IU: International Units
Some substances, such as certain vitamins, hormones and vaccines, are measured in IU (International Units) instead of milligrams. An IU is defined separately for each substance, so IU cannot be converted to mg with one general rule. Compare IU only with IU for the same ingredient.
Combination products
When a product contains more than one ingredient, the strength lists an amount for each, usually in the same order as the ingredients in the generic name. For example, a strength of "65 mg + 500 mg" on a product whose generic is Caffeine + Paracetamol would mean 65 mg of the first ingredient and 500 mg of the second.
See the strengths registered for Paracetamol
Search a brand to check its registered strength
Reading a strength tells you what is in a pack, not how much to take. For how much to take and how often, ask a registered doctor or pharmacist.
Frequently asked questions
Is mcg the same as mg?
What does 120 mg/5 mL mean?
What does 1% mean on a cream?
Can I convert IU to mg?
My pack's strength differs from the one I had before. What should I do?
This guide is general information only and is not medical advice. It does not tell you what any medicine is for or how to take it. For questions about your health or your medicines, ask a registered doctor or pharmacist.