Adjuvant anticholinergic therapy for the prevention of akathisia in patients with primary headache in the emergency department: A systematic review.

This review found insufficient evidence to recommend the use of diphenhydramine as an adjunct therapy to prevent akathisia in ED patients treated with neuroleptics or metoclopramide for primary headache. This finding relies on the results of two small randomized controlled trials with incomplete outcome reporting. Additional high-quality studies are needed to better understand the clinical efficacy of agents with anticholinergic properties in the ED management of patients with primary headaches.