Botulinum toxin injection is a minimally invasive treatment technique in which a dilute amount of botulinum toxin is injected into the spastic muscle (the target muscle causing the symptoms) to produce a chemical denervation effect to relieve muscle spasm and improve abnormal posture. The effect usually starts 3 days after injection and peaks in 1-2 weeks, with each treatment lasting about 3-6 months, and can be repeated as needed thereafter. Botulinum toxin is immunogenic and the interval between injections should not be shorter than 3 months in order to avoid the development of antibodies that may lead to a decrease in efficacy. In the field of neurology, indications for botulinum toxin injection treatment include: blepharospasm, oromandibular dystonia, Meige syndrome, spastic slant neck, writing spasms, lateral deviation spasms, sequelae of cerebral palsy, limb spastic states, migraine, hyperhidrosis, and other disorders. Botulinum toxin injections should be performed by a physician who has comprehensive knowledge of the disease and is familiar with the anatomy and physiology of the injection site, following the principle of individualization to seek the best results. Injections in the head and neck muscles can increase efficacy and reduce local adverse reactions, while the limb muscles tend to be confined to the center of the muscle belly, and injections in superficial target muscles are easy to locate, while deep target muscles often overlap with neighboring muscles and are obscured, requiring accurate localization under EMG or ultrasound guidance. The injection dose should be individualized, generally starting with a small dose, depending on the site of symptom involvement, the size of the spastic muscle, the degree of spasticity and the response to previous treatment …… This treatment has proven to have a high safety profile after years of clinical application. Treatment-related adverse effects include dry mouth, nausea, and general malaise in the first few days after injection, which are usually transient and resolve on their own. Botulinum toxin is a highly effective muscle relaxant and, given its mechanism of action, there is some risk of muscle paralysis with botulinum toxin injections. In fact, even with precise local injections, there is a possibility of toxin spreading. Related side effects include a feeling of facial muscle stiffness, asymmetrical facial lines, drooping eyelids, double vision, muscle weakness, and difficulty swallowing, etc. The symptoms are usually minor and can gradually recover with drug metabolism. Avoid local massage after injection to avoid aggravating the spread of toxin. In addition, as with any injection operation, local pain, infection, abnormal sensation, swelling, and bleeding associated with the injection can occur. Pain and/or tension from needling can lead to a vasovagal response, causing transient symptomatic hypotension and fainting. Contraindications to treatment include: (i) known hypersensitivity to botulinum toxin type A and any component of the formulation; (ii) presence of infection at the injection site; (iii) patients with myasthenia gravis or myasthenic syndrome; (iv) application of aminoglycoside antibiotics and other drugs that interfere with neuromuscular junction transmission (succinylcholine, cylindrotoxin, lincosamides, polymyxins, quinidine, magnesium sulfate, anticholinesterase agents, morphine, etc.); (v) pregnancy and lactating women; (6) the presence of bleeding disorders, hemophilia and anticoagulation therapy, it is recommended that oral aspirin patients stop taking the drug 3 days before injection.