Some drugs yield more than one benefit. For instance, β blockers have antihypertensive, antianginal, and antiarrhythmic effects. They also have more than one adverse effect. So we can talk about their benefits and harms. It's all to do with how you count.

The Danish philologist Otto Jespersen expounded the concept of count and non-count nouns in an unpublished lecture to the Copenhagen Academy of Sciences in 1911. As he explained in The Philosophy of Grammar (1924), you can form plurals if you can collect two things alike. For example, two bananas (two of the same thing). Or two fruits, an apple and an orange (two of the same kind). But we have no plural word for a journal plus a stethoscope, except to call them …