Feb. 8, 2008 -- The FDA today announced that it's investigating rare reports of serious adverse events linked with Botox, Botox Cosmetic, and Myobloc.
The most serious cases, in which patients died or were hospitalized, occurred in children with cerebral palsy who got botulinum toxin for severe arm and leg muscle spasms associated with their cerebral palsy. That's an unapproved use of the drugs.
No adult deaths have been linked to the drugs, but some adults have been hospitalized, including at least one person who used Botox for cosmetic uses. It's not clear if that case was due to Botox use. Adults' reported symptoms include difficulty holding up their heads, weakness, difficulty swallowing, and droopy eyelids.
The FDA isn't halting the drugs, but it is reviewing the products' labels.
The FDA advises patients and caregivers to watch for possible side effects including weakness, difficulty breathing, difficulty swallowing, and change in voice. Those effects have been reported as early as one day and as late as several weeks after treatment.
No Flaws Seen in Drugs
The three drugs -- Botox, Botox Cosmetic, and Myobloc -- contain tiny doses of botulinum toxin.
Botox, which is approved to treat eyelid spasms, neck spasms, and excessive sweating, contains botulinum toxin type A. So does Botox Cosmetic, which is used to treat facial frown lines.
Myobloc, which is approved to treat neck muscle spasms (cervical dystonia) in adults, contains botulinum toxin type B.
The reported cases involved approved and unapproved uses of the drugs. The cases aren't believed to be due to problems with the drugs.
There is "no reason to believe it's related to bad Botox," Russell Katz, MD, said at a news conference. Katz directs the neurology products division at the FDA's Center for Drug Evaluation and Research.
The FDA doesn't yet have final number of cases to report. So far, the FDA is aware of a "relative handful" of cases -- less than 100 -- says Katz.
He notes that although "very few" cases involved the cosmetic use of Botox, such cases are possible but would be "very unusual."
The watchdog group Public Citizen is calling for a "black box" warning for botulinum toxin products. Katz says that's "something to be considered, but it's still premature to say anything definitive about that."