Much of the contents of your medicine cabinet can be traced back to Chinese ingredients processed into pills in India. Thanks to the coronavirus, much of Chinese industry remains shut down. The potential ramifications of that for pharmaceuticals are now becoming clear.

India, which supplies around 40% of U.S. generic drugs, announced this week that it was restricting exports of 26 drug ingredients and medicines that use them, including several common antibiotics and the active ingredient in Tylenol. The news follows an announcement...