What is a drug class?
The Food and Drug Administration (FDA) organizes drugs into categories, or "classes," in many ways. Here drugs are organized by the conditions that they help to treat or prevent. Allergy drugs are one class, asthma drugs are another.
The FDA also groups drugs by their chemical ingredients, by the way a drug is used (by mouth, by injection, applied to the skin), by the organ in the body that they treat (stomach, head, eye), and so on. Any one of these categories is called a class, and any drug fitting the criteria belongs to that class of drugs.