The causes of children’s limb weakness and tenderness include physiological and pathological, pathological causes include hypokalemia, muscle weakness, etc. The treatment includes medication such as immunosuppressant, surgical treatment and so on. 1. Physiological factors: children’s prolonged over-exertion, excessive mental stress, anxiety and depression, and insufficient sleep due to late-night homework may cause weakness and tenderness of the limbs. Generally speaking, active physical exercise and good work and rest habits can effectively alleviate the symptoms. 2. Pathological factors: Hypokalemia is often manifested as loss of appetite, generalized weakness, increased nocturia, etc. Commonly used drugs include potassium chloride, potassium citrate, etc. Diseases such as Cushing’s syndrome can be treated by surgical resection. The main symptoms of myasthenia gravis are ptosis, double vision, etc. Commonly used drugs include azathioprine, etc., and serious conditions can be treated by surgery. When the child is not feeling well, he should go to the hospital immediately, and need to choose the drugs under the guidance of the doctor.