Why you may not need all those days of antibiotics

Green colonies of allergenic fungus Penicillium from air spores on a petri dish. Penicillin was the first antibiotic. Satirus/Shutterstock.com

A recent article in the British Medical Journal set off a bit of a firestorm with its claim that “the antibiotic course has had its day.” The authors challenged the very widespread belief that you should keep taking every last dose of antibiotic prescribed by your physician even after you feel better. This advice has long been claimed to be key to preventing antibiotic resistance.

The challenge to that claim has sparked a backlash, with physicians and public health officials expressing concern about an overly complex message that could result in encouraging patients to go rogue and ignore their doctors’ prescriptions.

All of this is a bit amusing to experts like me, who have been actively challenging this silly dogma for a long time, but without the recent media attention. So let me try to bring some clarity to the debate, which really isn’t that complex, so you understand what to do when your doctor gives you a prescription for antibiotics.

Why taking too much of an antibiotic is drug abuse

I’ll start with the bottom line first. It is absolutely false that continuing to take antibiotics after you feel completely better will reduce the emergence of antibiotic resistance. Quite to the contrary, it will very likely promote the emergence of antibiotic resistance!

How did we get to this point, with such a huge gulf between reality and dogma? And how could so much of the medical community have been so wrong for so long?

Let’s make one thing explicitly clear. Historically, doctors and patients have both been pretty dreadful about using antibiotics appropriately. We’ve long prescribed antibiotics out of fear and habit, not science.

Alexander Fleming, who discovered penicillin, warned that the drug and other antibiotics could be overused. Ministry of Information Photo Division Photographer

Indeed, as far back as 1945, Alexander Fleming, the man who discovered penicillin in 1928, warned the public that people were taking penicillin to treat diseases not caused by bacteria, and that this unnecessary use of penicillin was going to breed out antibiotic resistance. He warned that those who so abused penicillin would be “morally responsible” for the deaths that ensued from penicillin-resistant infections.

He was right.

The sad thing is, society never did listen. Recent data confirm that our use of antibiotics has gotten no better in the modern era.

It has been estimated that 30 to 50 percent of antibiotic use in the U.S. is unnecessary. In my opinion, those numbers are rather hilariously low. I would that estimate 75 percent or more of antibiotic use is unnecessary. You see, I, and experts like me, have a more stringent definition of when antibiotic use is appropriate or not, which includes giving too long a course of antibiotics to patients who need them.

The truth is, we do not know how long a course of antibiotics is necessary to treat most types of infections. Even in the modern scientific era, the primary basis for the duration of most courses of antibiotics is a decree Constantine the Great issued in A.D. 321 that the week would consist of seven days. That’s why your doctor gives you seven or 14 days’ worth of antibiotics!

If good old Constantine had decreed four days in a week, doctors would be prescribing antibiotics in four- or eight-day courses, rather than seven- or 14-day courses. I refer to seven- or 14-day antibiotic courses as “1 or 2 Constantine units” to underscore the absurdity of the basis for these durations.

But in the last two decades, we actually have had dozens of clinical trials published demonstrating that shorter courses of antibiotics are just as effective as longer courses (see table).