The mystery illness has prompted the CDC, the U.S. Food and Drug Administration and other public health officials to warn the public to cease vaping until they find more answers, but the use of e-cigarettes has long been known to have health risks, according to the CDC, and never was advised for young people, pregnant women and those who do not already use tobacco products. Despite that, the popularity of the devices among young people has increased dramatically in recent years, which is of particular concern to physicians. It also led to a crackdown on the marketing tactics of companies like Juul, as well as a call to ban flavored vaping liquid.