Botox 100IU (onabotulinumtoxinA), also called botulinum toxin type A, is made from the bacteria that causes botulism. Botu linum toxin blocks nerve activity in the muscles, causing a temporary reduction in muscle activity Botox is used to treat cervical dystonia (severe spasms in the neck muscles). It is also used to treat muscle spasms (stiffness) in the upper limbs (elbows, wrists, fingers) or lower limbs (ankles, toes). Botox is also used to treat severe underarm sweating (hyperhidrosis).