When neutralizing antibodies against Botulinum Toxin develop in the body, the effectiveness of the injection can be reduced7. However, it doesn't completely nullify the effects. Some level of effectiveness has been reported in patients with these neutralizing antibodies5,7. Even if neutralizing antibodies are present, adjusting the dosage or changing the formulation can still yield some level of effectiveness. However, if it remains ineffective, treatment may be administered with longer intervals (over 2 years). While extremely rare, there are cases where treatment may eventually need to be discontinued.