This handout is also available in Spanish . Botulinum toxin is a protein. It can stop some of the chemical messages that are sent from nerves. Botulinum toxin is used to stop muscle spasms because it blocks these messages.
Botulinum toxin is made by the same bacteria that causes food poisoning.
A high dose of botulinum toxin could be fatal, just as food poisoning can be fatal. However, the dose given in injections is so small that it's unlikely you'll have any harmful effects from the toxin. Botulinum toxin has been used safely in thousands of people. It has been used for more than 10 years. Your doctor may be considering botulinum toxin injections to treat certain muscle spasms on your face or eyelids.