The causes of numbness in the left hand and left leg are very many, and it is necessary to combine the patient’s medical history as well as relevant examinations to clarify the cause. If you are an elderly person, especially if you smoke, drink alcohol, have a salty diet, have high blood pressure, diabetes, high blood cholesterol, the possibility of cerebrovascular disease is more likely to be considered, and it is recommended that the patient go to the hospital for a head CT, MRI to make a clear diagnosis. Other causes, such as cervical disc herniation or lumbar disc herniation compression to the nerve root, can also appear on one side of the limb numbness. There are also rare peripheral nerve diseases, mostly caused by local trauma and long-term pressure. In addition, numbness in one limb can occur if the patient is taking a particular drug or has a history of localized chemical exposure.