A method for treating arrhythmia in a patient in need thereof comprises administering botulinum toxin to the patient. Botulinum toxin may be administered by subcutaneous or intradermal injection. The subcutaneous or intradermal injection may be administered to and/or around the vicinity of a trigeminal nerve, a cervical nerve, a thoracic nerve, a lumbar nerve, and/or a sacral nerve of the patient.