Thirty years ago, Henry Gadsden told Fortune that he wanted Merck to be more like chewing gum-maker Wrigley's. It had long been his dream to make drugs for healthy people--to "sell to everyone." Gadsden's dream now drives the marketing machinery of the most profitable industry on earth. Using their dominating influence in the world of medical science, drug companies are systematically working to widen the very boundaries that define illness. Old conditions are expanded and new ones created, and the markets for medication grow ever large. Runny noses are now allergic rhinitis, PMS has become a psychiatric disorder, and hyperactive children have ADD. When it comes to conditions like high cholesterol or low bone density, being "at risk" is sold as a disease in its own right. Selling Sickness reveals how widening the boundaries of illness and lowering the threshold for treatments is creating millions of new patients and billions in new profits. As ordinary life becomes increasingly medicalized, the industry moves ever closer to Gadsden's dream: "selling to everyone."