The side effects of thyroid ultrasonography may have some effect on the kidneys, and may also cause contrast allergy and local infection. 1. Kidney damage: The contrast agent has a relatively large molecular weight, and it has to be excreted from the kidneys, which is generally harmful to the kidneys, so drink plenty of water after the examination to promote the expulsion of the contrast agent. People with renal insufficiency should choose this test with caution. 2. Allergic reaction: If allergic to contrast medium can easily cause nausea, vomiting and other symptoms, or skin rash, redness and swelling, etc. If it is mild, no special treatment is needed, just pay attention to observation. If the reaction is severe, anti-allergy treatment is needed, such as applying anti-allergy ointment. If the patient is allergic to the contrast medium in the past, the patient should communicate with the doctor in advance, and the contrast medium can be changed. 3. Local infection: During the process of injecting contrast medium, there may be a risk of local infection to the skin at the injection site, so it is necessary to pay attention to keeping the skin at the injection site dry, sterilizing it with iodine povidone, and covering it with gauze if necessary. Contrast agent is used during thyroid ultrasonography. Drinking plenty of water after thyroid ultrasonography can promote the excretion of the contrast agent, and generally speaking, there is no great danger. However, there is a small risk of side effects in a few people. Thyroid ultrasonography should be performed at an authorized medical institution.