Methods and kits for treating or alleviating masseter muscle hypertrophy by local administration of a Clostridial derivative, such as a botulinum toxin, to the masseter muscle are described. Methods and kits for reducing lower face width and for reducing prominence of the masseter muscle of a human are also described.本案描述用於治療或減輕嚼肌肥大之方法或套組,其係藉由向該嚼肌局部投予梭菌衍生物(諸如肉毒桿菌毒素)。亦描述用於減少人類之下方臉部寬度及用於減少人類之該嚼肌之凸出之方法或套組。