Botulinum toxin is a very powerful neurotoxic poison. It is not filler. It paralyses the muscles temporarily. Wrinkles around the eyes and between brows are the results of muscle contractures. After neurotoxin injection muscles can not contract so the wrinkles caused by animation will not be seen. This neurotoxin also reduces sweating of palm, sole and axilla if injected into these areas. It is effective and harmless but effects are temporary and disappear in months.
There are many indications for botulinum toxin injections. Although wrinkle and excessive sweating treatments are the best known it is also be used to correct asymmetries of brows, brow elevation or brow lowering. If the muscle can not contract it will be decrease in volume that means it atrophies. The vertical bands in the neck is the result of visible anterior end of neck muscle (platysma muscle). Botulinum toxin injection into this bands will make them less visible. If the chewing muscle (masseter muscle) hypertrophies it creates strong and bulging jaw angles. This can also be treated with botulinum toxin injections.