A neurotoxin produced by certain strains of the bacterium Clostridium botulinum, also known as botulism toxin. When consumed in food, botulinum toxin, type A can cause paralysis and death. The neurotoxins produced by Clostridium botulinum are among the most potent poisons known. In a purified form, botulinum toxin, type A (known as Botox) has been used to treat blepharospasm (involuntary contraction of the eyelid), strabismus (crossed eyes), and esophageal achalasia (dilated esophagus). When injected under the skin, Botox reduces the appearance of wrinkles for up to 6 months, but then additional injections are needed.