The most common causes of hand and foot weakness in the elderly are as follows: First, cerebrovascular diseases: cerebrovascular diseases commonly include cerebral infarction and cerebral hemorrhage, with sudden onset and symptoms such as sensory impairment and urinary and fecal disorders in addition to hand and foot weakness. It is recommended to go to the neurology department of the hospital and make a clear diagnosis by reviewing the cranial CT or MRI, and patients who are diagnosed need to be hospitalized. Second, hypokalemia: Patients may have hypokalemia. Elderly people have irregular diet, less intake of vegetables and fruits, plus the absorption function decreases. If sweating is too much, it can easily lead to hypokalemia, which is also the main cause of weakness in hands and feet. Third, inflammation: pay attention to the exclusion of any inflammation in the body, especially pneumonia. Clinically, we often see many elderly people suddenly develop weakness in their hands and feet, which is found to be pneumonia through examination, so pneumonia can also cause weakness in the hands and feet of the elderly.