Arm pain after vaccination is a normal phenomenon, caused by the stimulation of nerves by vaccine components or poor absorption. However, if arm pain still exists 20 days after vaccination, in addition to excluding local damage, allergies and other factors, it should also be considered that the pain may not be related to vaccines and caused by other diseases. Common causes and treatment methods 1. Local injury: When vaccination is given, the absorption of locally injected drugs is slow, and the recovery time may be prolonged due to the stimulating effect of drugs on surrounding tissues and nerves, or slight damage to muscles and nerves at the vaccination site. If your arm still hurts after 20 days of vaccination, you can take methods such as hot compress and massage to relieve the pain, and if the effect is not good, you can go to the hospital for examination and follow the medical prescriptions for medication. 2. In the former case, allergic reactions may appear for a short time after vaccination, manifesting as fever, rash and angioneurotic edema. The latter may occur later and may also lead to arm pain 20 days after vaccination, which may manifest as muscle pain, joint pain, swollen lymph nodes, or fever, rash, proteinuria, etc. If there are similar manifestations, anti-allergy drugs such as chlorpheniramine maleate, cetirizine, loratadine, etc. can be taken under the guidance of a doctor to relieve symptoms; 3. Other diseases: Excluding the above factors, it is also possible that the vaccinees themselves have shoulder joint and cervical spine diseases, such as frozen shoulder and cervical spondylosis, which may also lead to arm pain, generally unrelated to vaccines. Patients are advised to seek medical attention and undergo relevant examinations to clarify the diagnosis. Precautions When arm pain still occurs after 20 days of vaccination, diet should be as light as possible, avoid smoking and drinking, and try to avoid spicy and stimulating foods, such as hot pot and chili. Try to work and rest regularly, avoid staying up late, and do moderate exercise and sports to help the body recover. If the symptoms persist or worsen, the vaccinees can contact the vaccination site and go to the hospital for examination and corresponding treatment.