On March 9th, 2010, the FDA approved Botox specifically for use to treat spasticity in the flexor muscles of the fingers, wrist and elbow. Spasticity can be common after traumatic brain injuries, stroke or in individuals with advanced multiple sclerosis. Botox works by causing a temporary paralysis of the spastic muscle, which increases flexibility of the muscle and decreases the stiffness and tightness associated with the spasticity.
The Boxed Warning does state that the effects of botulinum toxin may spread, causing difficulties in breathing and swallowing, which can be life-threatening. But, fatigue, nausea, muscle pain and weakness and symptoms of bronchitis were the most common adverse effects.
Botox has been used to treat plantar fasciitis, but it has not been approved by the FDA for this use. More information on the use of Botox in plantar fasciitis .