Taking iodine generally refers to taking iodine 131 medication. You can generally drink a moderate amount of water before taking iodine 131, and it is recommended that you consult your doctor about the precautions to be taken before the examination to avoid delaying the treatment. Before taking iodine 131, you need to fast for 2 hours, but you can drink a moderate amount of water. Before the examination, iodine-containing foods and medicines must be stopped for a certain period of time, such as seafood, iodized salt and other foods, as well as anti-thyroid drugs, thyroid hormones and other medicines. After taking iodine, you should pay attention to rest, avoid exertion, drink more water to speed up the metabolism after taking the medicine, and avoid close contact with children and pregnant women. The specific precautions for taking iodine can be consulted with your doctor for more details and treatment under the doctor’s guidance.