Despite repeated emphasis upon the distinction between dose and dosage, these two terms continue to baffle us. As we’ve often been told, dose refers to a specified amount of medication taken at one time. In the preferred use of dosage, however, the term refers to the administering of a specific amount, number, and frequency of doses over a specified period of time. Dosage implies duration: a “dosage regimen” is a treatment plan for administering a drug over a period of time. One way to absolutely never forget the distinction between dose and dosage is to focus on the meaning of the suffix –age in dosage. Dose will then be understood by default.

The ending –age has a number of meanings. For instance, place or residence (orphanage, a place that houses orphans); relationship, connection (parentage); an action (blockage, curettage); a condition (peerage) and a few others. But the meaning that’s relevant here is the one that has to do with a collection, mass, or overall amount. The suffix is added to a singular noun, which is semantically specific. For instance, driving to and from work you travel a certain number of miles a day in your car. However, the number recorded on the odometer represents the mileage (also spelled milage), that is the total number of miles the vehicle has traveled up to the present time. Dose and doses are comparable to mile and miles, respectively. Dosage is comparable to mileage. Terms belonging to the same set as dosage and mileage convey a cumulative effect, meaning that implicitly or explicitly a chronological element belongs to the overall sense of the words.

Similarly, a multi-acre farm is plowed acre by acre; and a certain number of acres may be plowed in one day. The plurality of acres can of course be called acres. But the plural can also be expressed as a collective, that is, as acreage—as in “corn acreage,” denoting the total number of corn-producing acres on a farm.

Words belonging to the same subset include cordage (cords or ropes collectively, as in the rigging of a ship); foliage (all the leaves on a growing plant; root Latin folium, leaf); leafage, the native English equivalent of foliage; footage, meaning 1) the total number of feet in a space, as in the “square footage” of your office, and 2) a length of film; lineage [pronounced as 2 syllables], also spelled linage, meaning the total number of written or printed lines in a text; plumage (the entire covering of feathers on a bird; root Latin pluma, down); sewage (the entire amount of liquid and water-borne wastes from households and industrial plants); sewerage (the entire sewer network of pipes, etc. used to treat sewage; sewerage is also sometimes used to mean ‘sewage’); and tonnage (the total number of tons of freight that a ship can carry).

Dosage is comparable to acreage, cordage, foliage, footage, leafage, lineage (linage), linkage (including its genetics sense), mileage (milage), plumage, rootage, sewage, sewerage, and tonnage.