It is important to note that the relative potencies of the various botulinum toxin products differ significantly within the toxin types and brands (Botox,Dysport,Xeomin and Myobloc). The potency of botulinum toxin is measured in functional units that correspond to the calculated median dose that would kill a mouse when injected into the stomach. Clinical doses range widely depending on the size of the muscle to be treated, the degree of muscle weakness required, and the specific botulinum toxin product used (the potency expressed in Units or U is not comparable from one botulinum toxin product to another). Spread of botulinum toxin effects is dose and brand dependant. Large doses rarely ever employed in cosmetic use can cause a Botulism – like effect. Botulism is a serious bacterial toxin-mediated neuroparalytic illness whose onset is typically marked by things such as double vision (diplopia), inability to control or coordinate the muscles used in speaking (dysarthria), and/or difficulty swallowing (dysphagia)), followed by progressive descending muscle Weakness or paralysis that can lead to respiratory failure and death. The clinical use of botulinum toxin products presents the potential for iatrogenic botulism, which may be described as the appearance of one or more clinical manifestations of botulism that has the potential to be clinically serious. This is can and has occured with cosmetic use. Local extension of effect of the botulinum toxin into anatomical structures (nerves and muscles) adjacent (contiguous) to the site of injection may occur and is described in product labeling.For example, dysphagia (difficulty swallowing) is described in product labeling as a "commonly reported adverse event following treatment with all botulinum toxins in cervical dystonia. It also has been seen when botulinum toxin products have been injected into the neck at doses as low as 60 units of Botox.also informed . the BLA ( Biologic License Application )or drug companies for various toxin products must also have a Approved Risk Evaluation and Mitigation Strategies (REMS) to ensure that the benefits of these products outweigh the potential for serious risks associated with the lack of interchangeability among the various botulinum toxin products.
There is also a lack of uniformity in the terminology used to characterize this adverse events associated with use of botulinum toxin products. Clinical seriousness may be considered with unintended extension of the toxin's neuromuscular blockade effects to anatomical structures beyond the targeted treatment site, whether these structures are close or far from the site of injection. Local weakness of the injected muscle(s) represents the expected pharmacological action of botulinumtoxin. However, weakness of adjacent muscles may also occur due to spread of toxin. On the other hand dysphagia or difficulty swallowing may also be a sign of distant spread of botulinum toxin effects when the agent is administered at a site other than the neck. This has been seen with a Myobloc (a type B toxin) in cosmetic doses and when large doses are used in everything from cerebral palsy to hyperhidrosis or excessive sweating,. The mechanism by which distant spread of the toxin effects occurs has not been well established. Patients must be aware of the reports systemic adverse reactions including respiratory compromise and death following the use of botulinum toxins types A and B for both FDA-approved and unapproved uses are suggestive of botulism, which occurs when botulinum toxin spreads in the body beyond the site where it was injected. The most serious cases had outcomes that included hospitalization and death, and occurred mostly in children treated for cerebral palsy-associated limb spasticity. Although current product labeling for Botox, Botox Cosmetic, Dysport and Myobloc contains a section advising physicians that patients with neuromuscular disorders may be at increased risk of clinically significant systemic effects, including severe difficulty swallowing and breathing and respiratory compromise, after local injection of typical doses of botulinum toxin, there is literature suggesting that "similar, potentially life-threatening systemic toxicity from the use of botulinum toxin products can also result after local injection in patients with other underlying conditions such as those with cerebral palsy associated limb spasticity." Back to the question...are any deaths which have been linked to Botox related to the cosmetic form of the toxin—and Allergan, the makers of Botox, went on record earlier this year to dispute the claim that the death of a woman in 2004 was caused by Botox Cosmetic. "In fact, says the California-based manufacturer, a medical review of this actual case demonstrates that the patient passed away in the winter of 2004 from complications associated with staphylococcus pneumonia, not from the Botox cosmetic treatment the patient received seven weeks earlier." However come again Botox use can result in pneumonia so a careful review of this case and another reported to the LA Coroner strongly indicates that Botox Cosmetic injected into the neck can and has very very rarely resulted in death.