MEDICAL PRESENTATION

Dose and Dosages

People often use dose and dosage interchangeably, but these terms have different meanings. Adding the suffix -age to the base word "dose" implies an overall amount. It can be compared to the difference between the words mile and mileage.

What Is a Dose?

The term "dose" refers to a specified amount of medication taken at one specific time.

According to the American Medical Association (AMA), drug doses are expressed in metric mass units—for example, milligrams (mg) or milligrams per kilogram (mg/kg). Some drugs, such as insulin or heparin, may be prepared as mixtures. For that reason, they have no specific molecular weight and can't be described in mass units.

There are a few exceptions, though. Liquid medications for the eyes and ears are sometimes measured in drops. Some medications are measured in grains. And other medications are dispensed using apothecary system measurements like teaspoonfuls, ounces, or drams. However, these are rare.

What Is a Dosage?

The AMA defines a dosage as how to take or give a medication as prescribed. "Dosage" is a much broader term than "dose." It involves a specific amount, number, and frequency of doses over a specific period of time.