“New and improved.” These words have been yoked together in so many marketing campaigns that we tend to accept them as inexorably linked. But when it comes to new medications, don't swallow them without a healthy dose of skepticism. Many or most new drugs are not—or at least not provably—an improvement over the best existing drug for a given condition, and the fast-track drug-approval processes that have prevailed in recent years have added to the uncertainty about their advantages.