Off-label use doesn't just apply to kids—and it is sometimes of great economic importance. For instance, a medication used for a certain cancer treatment is also effective for an eye problem of the elderly—a type of macular degeneration. When the drug is sold in little-bitty bottles for eye use under one brand name, it is staggeringly expensive. It is, however, much cheaper when an ophthalmologist draws tiny amounts from a big bottle of a virtually identical (but differently named and much less expensive) product made by the same company for cancer treatment.