system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does Iodine (pill form?) help reduce the effects of radiation poisoning if you’re already irradiated?
gpt
It doesn't. Potassium iodide does one thing and one thing only: It protects your thyroid by blocking it from taking up radioactive iodine-131 which can cause thyroid cancer. It does nothing if you take it after exposure and it doesn't protect any other part of your body or protect you from any other radionuclide.