WASHINGTON (March 9, 2010)—The U.S. Food and Drug Administration said Tuesday it has approved Allergan's drug Botox to treat spasms of the elbow, wrist and fingers.

Botox is best known for it's ability to smooth frown lines, but the drug has long been used to treat neck spasms and other muscle disorders.

Allergan will now be able to market Botox to adults for the treatment of spasticity in the flexor muscles of the elbow, wrist, and fingers.

Botox works by blocking the connections between nerves and muscle, temporarily paralyzing the spastic muscle.

The FDA stressed that Botox is not approved to treat arm or leg spasms.

Last year the agency added warnings to Botox about its potential to migrate from limbs to other parts of the body, causing breathing problems.