Rub a little whiskey on a baby’s gums. You’ve probably heard that home remedy for teething. But, what about a few teaspoons of bourbon to nip asthma symptoms or some sips of brandy to treat diabetes?

During Prohibition, the U.S. Treasury Department authorized physicians to write prescriptions for medicinal alcohol. Licensed doctors, with pads of government-issued prescription forms, like the one shown here, advised their patients to take regular doses of hooch to stave off a number of ailments—cancer, indigestion and depression among them...