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Ask the Expert: Questionable Advice


Does taking antibiotics until they’re gone really prevent resistance?

Antibiotics are usually dispensed with the caution to take the full course, even if the patient feels better, because it prevents resistance. The problem with this axiom is that it’s not, and never was, based on evidence. Infectious disease expert Louis B. Rice, MD , the Joukowsky Family Professor of Medicine and chair of the Department of Medicine, explains how this old saw came about and where we go from here.

To get antibiotics licensed, pharmaceutical companies had to choose a period of time for their clinical studies. If a drug was approved after a 10-day trial, the 10-day regimen was codified. But there’s no scientific basis for many of the regimen lengths we prescribe. It reflected the notion that antibiotics are safe drugs, they don’t have a lot of side effects, and so why not give more?

The reality is any dose of antibiotics that you take beyond what is absolutely needed only promotes resistance. Now we have a big resistance problem and we must find ways of reducing our consumption of antibiotics in order to decrease the selective pressure for resistance. You can’t and shouldn’t withhold antibiotics at the time of an acute infection. But two days later, when the patient feels better, that’s when you have a lot of leeway to say, you probably don’t need it anymore.

That’s why I think we should focus on treatment duration, because it doesn’t put the “antibiotic police” between a physician and his or her patient during the time of acute illness. Of course, we have to present our colleagues with data to show this practice is safe or, in fact, safer than continuing the antibiotic. The NIH is supporting studies that look at what the lengths of therapy should be, and identifying biomarkers that suggest a patient’s infected or that an infection is already treated.

If I could get people to stop thinking that taking the full course of antibiotics prevents resistance, I would be happy, because it makes absolutely no sense from a microbiologic, evolutionary, genetic point of view.


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