Symptoms and Signs

Patients with acute radiation syndrome progress through four phases, prodromal phase, latent phase, manifest illness phase and recovery or death.

Acute radiation syndrome usually affects blood cells, digestive tract, the brain and circulation. Symptoms appear within hours or weeks depending on the dose of the radiation. The patient goes through the following phases:

Prodromal Phase: The prodromal phase usually occurs within 48 hours but may be delayed up to 6 days following radiation exposure. An early prodrome indicates an exposure to a high dose of radiation.

Latent Phase: The patient shows apparent improvement during the latent phase, which may last from several days to a month.

Manifest Illness Phase: The patient suffers from low immunity during this phase and may recover if he/she survives this stage.

In the fourth stage, the patient may either recover or may die.

The patient may suffer from all the phases within a few hours if he/sheis exposed to a very high dose of radiation. This could result in death.

The effect of radiation of different body parts and systems is described below:

Blood cells: Blood cells fail to divide in the presence of high doses of radiation. This leads to a decrease in formation of all types of blood cells leading to infection, bleeding and poor wound healing. This could result in death.

Digestive Tract: Radiation damages the inner lining of the digestive tract. It causes symptoms like abdominal cramps, diarrhea, nausea and vomiting. Symptoms disappear during the latent phase, but reappear along with high fever in the manifest illness phase. Complications arising from the effect of radiation on the digestive tract include malnutrition due to decreased absorption from the intestines, dehydration, loss of electrolytes, low blood pressure, bowel obstruction and anemia. The patient could also suffer from sepsis and kidney failure.

Brain and Circulation: Radiation affects the blood supply to the brain. In the prodromal phase, the patient may appear disoriented, confused and in some cases show loss of balance and seizures. Apparent improvement takes place in the latent phase. The patient worsens in the manifest illness stage resulting in shock, which occurs due to very low blood pressure. Complications include brain edema (swelling of the brain), increase in intracranial pressure (increased pressure around the brain) and lack of oxygen to the brain thus resulting in brain damage.

Skin: The skin and the muscles under the skin may be damaged with severe injuries. The skin may show signs of redness, blistering, accumulation of fluid (edema) and loss of hair. Burns may occur due to heat rather than radiation. The skin may show signs of bleeding, infection and poor wound healing.


  1. Harrison’s Principles of Internal Medicine 17th edition
  2. Waselenko JK et al. Medical Management of the Acute Radiation Syndrome
  3. Recommendations of the Strategic National Stockpile Radiation Working Group. Ann Intern Med. 2004;140:1037-1051.

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