Potassium Iodide is an antiradiological agent used to prevent and treat Radiation Sickness due to exposure to ionising radiation. It works by protecting the thyroid gland, a part of the human body that is particularly sensitive to radiation poisoning. However, overuse is not recommended, as it does come with some notable side-effects (including goitre, headaches, allergic reactions, depression, vomiting, diarrhoea, rashes and abdominal pain).