Early Communication on Adverse Events from Botox and Myobloc

Posted on April 29, 2008

FDA has issued an early communication about serious adverse events, including respiratory failure and death, from Botox and Botox Cosmetic (Botulinum toxin Type A), and Myobloc (Botulinum toxin Type B). These events were related to how the product was used, and not to a defect in the manufacturing process. The events occurred one day to several weeks after treatment, and from a wide range of dosages.

In the affected patients, the botulinum toxin may have spread beyond the injection site and caused symptoms associated with botulism, including dysphagia and respiratory insufficiency. The most severe effects were seen in children, and the most commonly reported use in children was for limb spasticity in cerebral palsy, which is an unapproved use. Adverse reactions also occurred in patients receiving the drug for approved indications.

FDA is evaluating all the adverse event reports, as well as the medical literature in this area, and will let health professionals and the public know about any new information or conclusions.

In the meantime, healthcare professionals who use botulinum toxins should be alert to the potential for systemic effects from local injections, including dysphagia, dysphonia, weakness, dyspnea, or respiratory distress. They should tell patients and caregivers about the symptoms of botulism and to seek immediate medical attention if they occur.

Finally, practitioners should understand that the potency of botulinum toxin, which is expressed in "Units" ("U"), is not comparable from one botulinum toxin product to the next.

Additional Information:

FDA MedWatch Safety Alert. Botox, Botox Cosmetic (Botulinum toxin Type A), Myobloc (Botulinum toxin Type B). February 8, 2008.
http://www.fda.gov/medwatch/safety/2008/safety08.htm#botox

FDA Press Release. FDA Notifies Public of Adverse Reactions Linked to Botox Use. February 8, 2008.
http://www.fda.gov/bbs/topics/NEWS/2008/NEW01796.html