Health authorities in the United States say they are investigating reports of serious side effects linked with treatments involving Botox.
The Food and Drug Administration (FDA) says they have received some reports of serious adverse events linked with Botox, Botox Cosmetic, and Myobloc.
The three drugs contain small doses of botulinum toxin; Botox which contains botulinum toxin type A, is approved to treat eyelid spasms, neck spasms, and excessive sweating, along with Botox Cosmetic, which is used to treat facial frown lines.
Myobloc, which contains botulinum toxin type B, is approved to treat neck muscle spasms in adults.
The most serious cases involved children treated for spasticity in their limbs associated with cerebral palsy; this is not an FDA-approved use of botulism toxins in children or adults.
It appears the adverse reactions were related to the spread of the toxin to areas distant from the site of injection, and mimic symptoms of botulism, which may include difficulty swallowing, weakness and respiratory problems.
Although no adult deaths have been linked to the drugs, some adults have been hospitalized, including at least one person who used Botox for cosmetic uses and there have been reports of adults experiencing symptoms such as difficulty holding up their heads, weakness, difficulty swallowing, and droopy eyelids.