The first disease to consider in a patient with sudden dizziness and loss of consciousness is acute cerebrovascular disease. Dizziness and loss of consciousness are considered to be the result of brainstem ischemia or infarction. Because the brainstem contains the body’s upward reticular activating system, the reticular activating system governs the level of consciousness of a person. In cases of ischemia or infarction, the patient will experience a loss of consciousness. It is also necessary to improve the examination to exclude cardiogenic factors, for example, in the case of malignant arrhythmia, the heart cannot eject blood effectively, the brain does not receive an effective blood supply, and the patient will also experience dizziness and loss of consciousness, but the patient is often accompanied by discomfort such as heartburn and chest tightness. In addition, reflex syncope and epilepsy also need to be ruled out. It is recommended that patients who experience dizziness and loss of consciousness should seek medical attention promptly to improve the examination and clarify the diagnosis.