Dexamethasone in the morning and numbness in the arm at night mostly refers to the symptoms that appear after the closed injection treatment of the upper limb, and the possible causes are needle prick injury, anesthetic effect, adverse drug reaction, etc. 1. Needle injury: when injecting drugs into the closed area, some tiny nerves may be pierced, causing nerve damage and leading to numbness. Generally, it can be relieved by itself after proper rest. 2. Numbing effect: When the drug closure treatment is carried out, usually lidocaine and dexamethasone are used together, and lidocaine is a kind of anesthetic, which may also cause numbness in the upper limbs. When the drug is absorbed, the numbness can be gradually relieved. 3. Adverse drug reactions: Dexamethasone is an adrenocorticotropic hormone drug with anti-inflammatory, anti-allergic and immunosuppressive effects. Adverse reactions include allergy, joint swelling, skin rash, dizziness and headache, nausea and vomiting. It does not usually cause numbness in the upper extremities, but it cannot be completely ruled out. Numbness of the upper limbs after playing dexamethasone may also be related to cervical spondylosis and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in time to identify the cause of the disease and then standardized treatment.