The sudden onset of limb weakness in the elderly may be due to acute cardiovascular disease, which may cause weakness and swelling of the limbs in addition to heart-related symptoms. It may also be due to Parkinson’s disease, which causes limb weakness, delayed movement, and increased muscle tone; or cerebrovascular disease, such as cerebral infarction, cerebral hemorrhage, or subarachnoid hemorrhage, which may cause limb weakness; or hypokalemia due to hyperthyroidism or aldosteronism, which may cause limb weakness. The above discomfort can also be caused by hypokalemia. When elderly people develop hypokalemia, they tend to have weakness and numbness in their limbs. Therefore, if the elderly suddenly experience weakness in the limbs, it is important to go to a regular hospital in a timely manner.