In the dosage formula, which statement is true about units?

• A. Write units in the formula, cancel them out, and reduce
• B. Units are optional and can be ignored
• C. Units must be boxed in red
• D. Units should always be kept separate from numbers

Answer: (A)

Dimensional consistency is essential in dosage calculations. Write units with every quantity in the formula, then cancel those units as you multiply or divide, and reduce to the final unit that matches the prescribed dose. For example, when using a dose of 5 mg per kg for a patient who weighs 12 kg, multiply 5 mg/kg by 12 kg to get 60 mg; the kilograms cancel, leaving mg. This process helps ensure you’re delivering the correct form and amount of medication and catch errors like mixing units (mg with g or mL with L) before giving the dose. Ignoring units, boxing them separately, or keeping them out of the calculation undermines this safeguard and can lead to substantial dosing mistakes.