Radiation sickness

• ANATOMY OR SYSTEM AFFECTED: Gastrointestinal system, hair, skin, stomach

DEFINITION: An acute illness that occurs when an individual is exposed to a sudden, large dose of ionizing radiation (from X-rays, gamma rays, and particle bombardments)

Causes and Symptoms

Typical symptoms of radiation sickness are nausea, diarrhea, skin burns, internal bleeding, and severe anemia. The production of blood corpuscles in the bone marrow is inhibited, and the ability of the body to fight infection is reduced.

The severity of radiation sickness depends on the dose, which is commonly measured in units called rads (an acronym for "radiation absorbed dose"). For humans, a whole-body dose greater than 600 rads is usually fatal. At 450 rads, there is a 50 percent survival rate. Below 50 rads, no symptoms of radiation sickness are observable, although the risk of cancer is somewhat higher than normal.

Radiation therapy for cancer patients has typically been prescribed in total doses of about 5,000 rads. Such large doses are not fatal for two reasons: first, only a small region of the body (the actual cancer site) is irradiated; and second, the therapy is given in smaller doses of about 200 rads over a period of several weeks so that the body has time to recover between treatments.

Treatment and Therapy

Once radiation damage occurs, little can be done to repair it directly. Immediate treatment involves washing the body with soap and lukewarm water to remove radioactive material and monitoring the levels of radiation in the body. This monitoring continues throughout the course of treatment, which centers on whichever parts of the body have been affected and focuses on helping the body’s natural processes of recovery. Vomiting and diarrhea can be controlled with drugs, while bacterial infections and wounds are treated with antibiotics. In extreme cases, a bone marrow transplant can be performed to reestablish the formation of new blood cells. Donor cells are not likely to be rejected because the body’s immune system has been inactivated temporarily by the radiation. In cases of specific radiation exposure, there do exist a handful of targeted therapies that target specific internal organ damage, such as potassium iodide and Prussian blue. However, in cases of lethal radiation exposure, end-of-life palliative care should be offered.

Into the mid-2020s, radiation sickness is often referred to as acute radiation syndrome (ARS). Radiation dose is measured in grays (Gy) and sieverts (Sv), with about 4–5 Gy representing a 50 percent mortality rate without advanced treatment. Therapy is supportive and includes intravenous fluids, antibiotics, pain and nausea control, and, in some cases, hematopoietic stem-cell transplantation. Colony-stimulating factors such as filgrastim or sargramostim are used to restore bone marrow function. Targeted antidotes continue to be available.

Bibliography

Frigerio, Norman A. Your Body and Radiation. Rev. ed., US Atomic Energy Commission, 1967.

Hall, Eric J. Radiation and Life. 2nd ed., Pergamon, 1984.

Ogura, Toyofumi. Letters from the End of the World: A Firsthand Account of the Bombing of Hiroshima. Trans. Kisaburo Murakami and Shigeru Fujii. Kodansha, 2001.

Prasad, Kedar N. Handbook of Radiobiology. 2nd ed. CRC, 1995.

“Radiation Basics.” Environmental Protection Agency, 1 Oct. 2024, www.epa.gov/radiation/radiation-basics. Accessed 22 Aug. 2025.

“Radiation Exposure and Cancer Risk.” American Cancer Society, www.cancer.org/cancer/risk-prevention/radiation-exposure.html. Accessed 22 Aug. 2025.

“Radiation Sickness.” Cleveland Clinic, 11 June 2024, my.clevelandclinic.org/health/diseases/24328-radiation-sickness. Accessed 22 Aug. 2025.

“Radiation Sickness.” MedlinePlus, 1 July 2023, medlineplus.gov/ency/article/000026.htm. Accessed 22 Aug. 2025.

“Radiation Sickness - Diagnosis and Treatment.” Mayo Clinic, 13 Feb. 2024, www.mayoclinic.org/diseases-conditions/radiation-sickness/diagnosis-treatment/drc-20377061. Accessed 22 Aug. 2025.