In the recent flap over chloroquine and its relative hydroxychloroquine, drugs seen as promising in many quarters for use in treating COVID-19 patients, one commentator typical of many sternly proclaimed that these compounds “have NOT been proven effective against” the novel coronavirus. Implication: These are drugs no reasonable person would want to take, nor a reasonable doctor prescribe.

And yet, as Arizona physician Jeffrey Singer notes, “Doctors around the globe, including the U.S., are using these and other drugs to treat their patients, and reporting on their findings in the peer-reviewed medical literature.” It’s both legal and utterly routine for doctors to prescribe a drug for indications other than the one for which it has been approved — so-called “off-label prescribing.” In fact, an estimated 20% of pharmaceuticals reach patients that way. (More on the practice here, here, and here.) And this will be true almost by definition for a newly emergent malady, for which there will be no compounds proven effective yet.