Numbness on the left side of the face can be caused by a variety of reasons and may not necessarily be a precursor to a blood clot, but requires a visit to the neurology department of a hospital to determine the specific cause. In addition to numbness in the left side of the face, other conditions such as abnormal sensation in other parts of the face, aphasia, slanting of the mouth, slurred speech, unsteady gait, headache, etc. may also occur depending on the location of the blockage. In addition, numbness in the left side of the face may also be a manifestation of idiopathic facial nerve palsy, allergy, or pre-rash of herpes zoster. Patients are advised to go to the neurology department of the hospital for MRI examination to clarify the cause and provide targeted treatment. Some patients with cerebral thrombosis may experience transient cerebral ischemic attacks, with the main symptoms being dizziness, inability to speak, and limb weakness lasting for seconds or minutes. If middle-aged or elderly people develop the above symptoms, it is recommended to visit the neurology department for examination in time and take preventive measures in advance to avoid serious cerebral infarction attacks.