A Therapeutic Double-edged Sword: Weighing the Good, the Bad, and the Ugly of Antibiotics

How common are adverse reactions to antibiotics?

When a prescription is written for warfarin, all the risks of therapy are usually appreciated. The same may be said for other potentially problematic drugs, including lithium and phenytoin. Is the same circumspect reflection exercised during the all-too-common practice of prescribing antibiotics for trivial illnesses, such as viral upper respiratory tract infections (URTIs)?

The evidence suggests that myriad antibiotic risks are still being taken for granted. The "event rate" (those events leading to an emergency department [ED] visit, for example, as a result of an allergic reaction) is 3 times higher for antibiotics than for lithium and phenytoin— drugs known to have a narrow therapeutic range. A recent paper and accompanying editorial provide yet another caution about a dangerous, but pervasive clinical habit.^1,2

ANTIBIOTIC ADVERSE EFFECTS SEND MANY TO THE ED

From 2004 to 2006, 140,000 ED visits each year in the United States were the result of an antibiotic prescription; these represented about one-fifth of all ED visits related to adverse drug effects. Allergic reactions were responsible for nearly 80% of the ED visits, and diarrhea, headaches, and dizziness accounted for the remainder. As expected, penicillins caused nearly 37% of these events; however, vancomycin and linezolid were responsible for nearly twice as many. Most adverse events were caused by a single antibiotic in patients who were not taking other medications. The authors of the paper concluded that "minimizing unnecessary antibiotic use even by a small percentage could significantly reduce the immediate and direct risks of drug-related adverse events in individual patients."¹

A KEY CULPRIT: ANTIBIOTICS FOR URTIS

Focusing on the setting where the abuse of antibiotics may be the most blatant, the editorialist who commented on the study singled out URTIs.² Based on an analysis of 3.⁴ million respiratory tract infection visits in a United Kingdom primary care database, the number needed to treat this entity with antibiotics to prevent one complication is greater than 4000 individuals. The editorialist concluded that our present prescribing practices are harmful and contravene compelling data from evidence- based medicine.

AN EVEN STRONGER CASE FOR MINIMIZING ANTIBIOTIC USE

I have visited the downside of antibiotic use in several previous columns.^3-5 However, this most recent caution must be added to the others as a novel perspective on a disturbing equation. The prior caveats addressed only Clostridium difficile and the development of resistance, not the broader scope of issues defined by this study. That is exactly why a revisit is timely. There is a growing concern that the previous evidence marshaled against questionable antibiotic prescribing practices is not being heeded. Now is the time to reevaluate and change a potentially dangerous practice.