In a radiation emergency, radioactive iodine may be released in the air.This material may be breathed or swallowed. It may enter the thyroid gland and damage it. The damage would probably not show itself for years. Children are most likely to have thyroid damage.

Who Should Not Take Potassium Iodide:
The only people who should not take potassium iodide are people who know they are allergic to iodide. You may take potassium iodide even if you are taking medicines for a thyroid problem a thyroid hormone or antithyroid drug.
If you take potassium iodide, it will fill up your thyroid gland. This reduces the chance that harmful radioactive iodine will enter the thyroid gland. Pregnant and nursing women and babies and children may also take this drug.
How And When To Take Potassium Iodide:

Potassium iodide should be taken as soon as possible after public health officials tell you.You should take one dose every 24 hours. More will not help you because the thyroid can "hold" only limited amounts of iodine.Larger doses will increase the risk of side effects. Do not take the drug for more than 10 days.

Side Effects:
Usually effects of potassium iodide happen when people take higher doses for a long time. You should be careful not to take more than the recommended. Side effects are unlikely because of the low dose and the short time you take the drug.

Possible side effects:
include skin rashes,swelling of the salivary glands & iodism metallic taste,burning mouth and throat,sore teeth & gums,symptoms of a head cold & sometimes stomach upset & diarrhea.Few people have an allergic reaction with more serious symptoms.These could be fever and joint pains, or swelling of parts of the face or body and at times severe shortness of breath requiring immediate medical attention. If Side Effects are severe call a doctor or public health authority.