Patients with cerebral blood supply deficiency are not recommended to drink coffee because coffee contains a certain amount of caffeine, which is an alkaloid that excites the central nervous system. Drinking coffee can also play a role in constricting the blood vessels in the heart and brain. If the patient has cerebral blood supply deficiency, drinking coffee can cause constriction of the cerebral blood vessels, and in severe cases, it can also lead to cerebral vasospasm. Patients can experience an increase in the symptoms of insufficient blood supply to the brain, and in severe cases, headache, nausea, vomiting, etc. Therefore, coffee is not recommended for patients with insufficient blood supply to the brain. Drinking coffee can also cause vasoconstriction of the heart, which can lead to panic attacks and increased heart rate, so coffee is not recommended for patients with atherosclerosis and cerebral insufficiency. If the patient has a headache or dizziness after drinking coffee, drink more water to facilitate the metabolism of caffeine.