Can excessive use of botox cause complications in the brain or central nervous system?

It depends: Botox is used for many theraputic and cosmetic purposes. The amount used for cosmetic purposes is very small and there is no indication that it can cause any nervous system complications. A much higher dose is used for some theraputic purposes and it is possible for it to travel to the central nervous system but at this time there is no indication of any complications when used apppropirately.

Excessive Botox?: It depends on what you mean by excessive. Agree with dr ourian. Botox has been used for therapeutic and cosmetic indications without brain or CNS complications when used in recommended dosing. The effects of Botox are temporary, so treatments need to be repeated to maintain the desired effect. Returning for additional treatment after the effects have worn off is not considered excessive use.

Moderation: Moderation is the key. On average Botox provides results for 3-6 months. There have not been any deaths from Botox for cosmetic reasons that i know of. Repeated large doses of Botox for muscular or neurologic problems have caused several deaths.