Emergency Room Practices Stuck in Time

A recent study has found that emergency departments in the U.S. have shown no significant change in their use of diphenhydramine for treating anaphylaxis and urticaria, despite updated guidelines from 2020 advising against the use of this first-generation antihistamine.

Rising Cases of Anaphylaxis Underscore the Need for Change

An alarming 1.6% of the population suffers from anaphylactic reactions, and emergency department visits for these cases have skyrocketed, constituting 0.4% of all admissions. A nationwide study documented over 405,000 visits for anaphylaxis between 2008 and 2016, reflecting a shocking 2.3-fold increase in prevalence during that period.

Diphenhydramine: A Double-Edged Sword

Despite being the most commonly used antihistamine in emergency settings, diphenhydramine is fraught with risks. This IV treatment can lead to serious side effects, including sedation, dizziness, and even overdose-related fatalities. The medical community is increasingly concerned about its safety, especially when more effective and safer options are available.

The Shift to Second-Generation Antihistamines

Research has revealed that second-generation antihistamines offer comparable efficacy with far fewer side effects. They do not cross the blood-brain barrier, meaning patients are less likely to experience drowsiness or cognitive impairment—problems that plagues users of diphenhydramine.

Guidelines that Disrupt the Status Quo

The 2020 guidelines from the American Academy of Allergy, Asthma, & Immunology (AAAAI) have made clear recommendations against the use of first-generation antihistamines during the acute phase of anaphylaxis, advocating instead for epinephrine as the first-line treatment. Yet, despite this clear directive, diphenhydramine's use remains stubbornly high.

A Call for Change in Emergency Medicine

Led by Jazeb Ifikhar from the University of Oklahoma, a recent cross-sectional analysis examined diphenhydramine's usage in U.S. emergency departments between 2019 and 2021. Utilizing data from the Centers for Disease Control and Prevention, the researchers found that 61.99% of patients with anaphylaxis or urticaria received a diphenhydramine prescription, with little change from 2019 to 2021.

Breaking the Cycle: The Need for Future Research

Despite clear evidence and updated guidelines, diphenhydramine's prevalence in treatments remains worryingly unchanged. The study's authors emphasize the need for urgent research to uncover the barriers that prevent these guidelines from being implemented in emergency departments. Bridging the gap between established evidence and practical application is vital for improving patient care in anaphylaxis and urticaria.