What Is Acute Radiation Syndrome?

The CDC defines acute radiation syndrome, or ARS, sometimes known as acute radiation sickness, as an acute illness caused by irradiation of the entire body, or most of it, by a high dose of penetrating radiation in a very short period of time, usually a matter of minutes. Its clinical guidance says the dose may not be uniform, but a large portion of the body must have received more than 0.7 Gy (70 rads). The CDC says cutaneous radiation injury happens when exposure to a large dose of radiation injures the skin, and that people with symptoms should seek medical attention as soon as emergency officials say it is safe.

The CDC describes four stages. In the prodromal stage, nausea, vomiting, loss of appetite and possibly diarrhea occur from minutes to days after exposure. In the latent stage, the patient looks and feels generally healthy for a few hours or up to a few weeks. In the manifest illness stage, symptoms depend on the specific syndrome and last from hours up to several months. The last stage is recovery or death, and the CDC says most patients who do not recover die within months of exposure, while recovery lasts from several weeks up to two years.

The CDC says treatment of ARS focuses on reducing and treating infections, maintaining hydration, and treating injuries and burns, that the lower the radiation dose the more likely a person is to recover, and that some patients may benefit from treatments that help the bone marrow recover its function. It says the cause of death in most cases is destruction of the bone marrow, which results in infections and internal bleeding.

For a radiation emergency, CDC guidance explains that get inside means to find a building and take shelter, stay inside means to close and lock doors and windows and shelter in place to reduce exposure, and stay tuned means listening to emergency officials and using technology to stay informed. The CDC says potassium iodide protects only the thyroid and only against radioactive iodine, not other radioactive materials, must be taken within 24 hours before or 4 hours after exposure to be most effective, cannot reverse damage already done to the thyroid, and may not give 100% thyroid protection.