Generally speaking, the hazards of CT brain are minimal. Although CT brain has a certain degree of radiation, its dose is relatively small and the radiation dose is acceptable for CT brain examinations performed for medical purposes, and can be considered to have no significant side effects on the human body. CT of the brain is sometimes performed with a contrast agent, which is generally safe. However, in some cases, the contrast agent may cause allergy, as long as timely symptomatic treatment, generally will be quickly recovered, after the enhanced brain CT need to drink more water to accelerate the excretion of contrast agent in the body can be.