Radiation sickness (also called acute radiation syndrome) happens when a person is exposed to large amounts of radiation all at once.
Exposure to small amounts of radiation—like from an X-ray or CT scan—doesn't cause any symptoms. But exposure to large amounts of radiation all at once—like from a nuclear accident—may cause radiation sickness and death.
Symptoms of radiation sickness may include:
Nausea, vomiting, and diarrhea.
Feeling weak, faint, or dizzy.
Skin redness, itching, swelling, or burns.
People who have been exposed to large amounts of radiation and have these symptoms need to see a doctor right away.