If you’ve ever been prescribed an antibiotic, you were probably told to take every last pill, even if you start feeling better a few days in. Conventional wisdom held that stopping a prescription early could cause the bacteria to come back in an antibiotic-resistant form.
Despite the prevalence of this advice, the “finish the course” rule isn’t supported by evidence, professor Martin Llewelyn and colleagues write in an editorial in The BMJ. While there are a few specific infections that can develop resistance due to inadequate dosing (such as tuberculosis, gonorrhea, and HIV), most antibiotic resistance is caused by so-called “opportunistic” bacteria that live inside us and are replaced by resistant strains when we take antibiotics. Thus, Llewelyn and co-authors argue, exposing a patient to more antibiotics by finishing a prescription unnecessarily actually increases the risk for a resistant infection.
How did finishing the course of antibiotics become such common advice? The authors point to Dr. Alexander Fleming and other penicillin researchers, who saw that bacteria in the lab could become resistant. They were the first to warn warned doctors of the possibility of resistant infections from not using enough drug. Since then, finishing the course has been embedded in common knowledge, with few doctors speaking up against it.
This rule is just one of many established maxims that persist in medicine with little or no evidence. Others include the idea that giving peanuts to young children causes allergies (evidence shows that the opposite is true) and that you should eat a “BRAT diet” for upset stomach (doctors now recommend a regular diet).
The authors of the editorial speculate that such rules stick around because they are “simple and unambiguous, and the behavior it advocates is clearly defined and easy to carry out.” Indeed, it’s easy to remember to take all of your antibiotics; it’s more of a hassle to have a conversation with your doctor about when you can stop. But the authors are optimistic about the potential for cultural change on this issue, if doctors start telling patients to continue with their medication until symptoms are gone.