Most children with a condition that causes a temporary weakness or paralysis of the muscles in the face recover without medication within six months, according to a new study.

The research, led by the Murdoch Children's Research Institute and published in Neurology, found the steroid prednisolone does not significantly impact on a child's recovery from Bell's palsy.

Murdoch Children's Professor Franz Babl said while studies had shown steroid use in adults with Bell's palsy helped improve symptoms by minimising facial nerve swelling and damage within the temporal bone, similar research hadn't been available for children.

The randomised-controlled trial involved 187 participants, aged six months to 17 years, who presented to emergency departments (EDs) with Bell's palsy. The study was staged in 11 ED's in the Paediatric Research in Emergency Departments International Collaborative (PREDICT) research network in Australia and New Zealand. They were recruited within 72 hours after symptom onset and received 10 days of treatment with prednisolone or a placebo (no active drug).

The study found 57 per cent of those who didn't take any medication recovered facial function at one month, 85 per cent at three months and 93 per cent at six months. For those assigned prednisolone, 49 per cent recovered at one month, 90 per cent at three months and 99 per cent at six months. There were no serious side effects recorded during the trial and the most common adverse reactions were temporary changes in behaviour and increased appetite.

Bell's palsy, which causes half of the face to droop, is the third most common condition causing a sudden change in nerve function in children. In most cases the exact cause of the facial weakness is unknown but may be related to a viral infection.

"The lack of evidence on the use of steroids in children with Bell's palsy in children has led to variable practice in their treatment," Professor Babl said. Discovering that early treatment with prednisolone doesn't hasten recovery will help GPs, emergency physicians and paediatricians in their discussion with affected families and make better informed decisions."