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Evidence-Based Pediatrics Web Site

Acyclovir Does Not Improve Functional Outcome In Patients with Bellís Palsy


  • In patients with Bell's palsy, does treatment with acyclovir improve speed of recovery or overall function when compared to placebo?

Clinical Bottom Lines

  1. Generally favorable outcome for patients receiving double placebo.
    • 64.7% recovery at 3mo.
    • 85.2% recovery at 9mo.
  2. Improved outcome with Prednisolone (+/- Acyclovir) within 72hrs of symptom onset.
    • 83.0% recovery at 3mo (ARR 18%, NNT 6).
    • 94.4% recovery at 9mo (ARR 9%, NNT 11).
  3. No significant change in outcome with Acyclovir use at either time point.

Summary of Key Evidence

  • Double-blind, placebo-controlled, randomized factorial trial.1
  • Patients >16yo with unilateral facial nerve weakness of no identifiable cause presenting to PCP, ED, or dentist (88% coverage of total population of Scotland).
  • Patients referred to participating ENT within 72hrs of symptom onset, scored according to House-Brackmann grading system.
  • Patients randomized to treatment group at ENT office (Acyclovir 400mg PO 5x/day and Prednisolone 25mg PO BID, 10 day course for each).
    • Acyclovir + placebo
    • Acyclovir + Prednisolone
    • placebo + Prednisolone
    • placebo + placebo

Additional Comments

  • Recent study may show some efficacy for Valacyclovir + steroids vs. placebo + steroids.2


  1. Sullivan FM, et al.  Early treatment with prednisolone or acyclovir in Bell's palsy. N Engl J Med 2007;357:1598-1607.
  2. Hato N, et al. Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study. Otol Neurotol 2007;28:408-13.

CAT Author: David Van Mater, MD, PhD

CAT Appraisers: Kerry Mychaliska, MD

Date appraised: December 19, 2007

Last updated October 29, 2008
Department of Pediatrics and Communicable Diseases
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