Most of the contrast agents are iodine agents, and generally the amount of conventional contrast use will not cause damage to the human body, but a few exceptions, such as improper use of contrast agents, allergy to contrast agents, etc., will cause certain harm to the body, the specific hazards are as follows: 1, mild allergic reactions: including nausea, low fever, facial flushing, hives, itchy throat, etc., these reactions are usually transient and do not require special treatment, but be promptly Alert, it may also be the precursor of severe allergic reactions; 2, moderate allergic reactions: including laryngeal edema, dyspnea, hoarseness, tracheospasm, etc., which need to be treated with epinephrine and oxygen according to the situation; 3, severe adverse reactions: including large facial edema, urticaria, dyspnea, laryngeal edema with wheezing, which can lead to shock in severe cases and need timely symptomatic treatment. In addition, the use of contrast agent during the examination will eventually be excreted through the kidneys, which may increase the burden on the kidneys in the process, requiring more water to accelerate excretion after the contrast procedure.