Between 11 and 40 people in every 100,000 are affected by the condition, which causes paralysis on one side of the face. Paralysis is usually temporary, but a third of people suffer ongoing problems including facial disfigurement, pain and psychological difficulties.

Antiviral medications are widely prescribed to treat the condition, because studies have indicated that Bell's palsy may be associated with the same virus that causes cold sores (herpes simplex). Previous Cochrane Systematic Reviews did not find sufficient evidence to determine whether or not antiviral medications are effective.

In the current review, the researchers considered data from seven trials that together include 1,987 people. Antivirals were no more effective than placebo. Antivirals were also significantly less effective than steroid drugs called corticosteroids which will be the subject of another Cochrane Review in progress.

"The evidence from this review shows that antivirals used for herpes simplex offer no benefit for people with Bell's palsy. These results cast doubt on research that suggests herpes simplex causes the condition," said Pauline Lockhart, who is based at the Centre for Primary Care and Population Research at the University of Dundee. "In view of this, further research should be aimed at discovering alternative causes and treatments."

"It is worth pointing out that a 10 day course of the antivirals often prescribed for Bell's palsy can cost in excess of £10 in the UK. Obviously widespread prescription of drugs that we know do not work is a waste of resources."

Note: If no author is given, the source is cited instead.

• Herpes
• Cerebral Palsy
• Pharmacology

• Disorders and Syndromes
• Addiction
• Behavior

• Antiviral drug
• Evidence-based medicine
• Lyme disease
• Encephalitis
• COX-2 inhibitor
• Clinical trial