Bell's palsy is a disease of the facial nerve which causes one side of the face to be paralysed. Some studies have suggested that it is caused by infection with the cold sore (herpes simplex) virus. If this is correct, antiviral drugs against herpes simplex would be likely to help recovery. It has also been suggested that corticosteroids may help. The paralysis is usually temporary even when untreated, although without treatment about one person in five is left with permanent facial disfigurement or pain.
This updated review provided high quality evidence that antivirals are no more effective than placebo (dummy) treatment in producing complete recovery. On the other hand moderate quality evidence showed that antivirals were less effective than corticosteroids and that combined antiviral-corticosteroid treatment were more effective than placebo. Taken together, these results suggest that corticosteroids might be effective but this requires confirmation from the Cochrane review of corticosteroids which is being updated. There was no evidence that antivirals produced significantly more or significantly fewer adverse events than dummy treatment.
As this analysis shows that antivirals against the cold sore virus are not significantly effective, other causes for Bell's palsy than infection by the cold sore virus now need to be considered.