Acute radiation syndrome




Acute Radiation Syndrome (ARS) (sometimes known as radiation toxicity or radiation sickness) is an acute illness caused by irradiation of the entire body (or most of the body) by a high dose of penetrating radiation in a very short period of time (usually a matter of minutes).

The three classic ARS Syndromes are:

Bone marrow syndrome (sometimes referred to as hematopoietic syndrome): The survival rate of patients with this syndrome decreases with increasing dose. The primary cause of death is the destruction of the bone marrow, resulting in infection and hemorrhage.

Gastrointestinal (GI) syndrome: Survival is extremely unlikely with this syndrome. Destructive and irreparable changes in the GI tract and bone marrow usually cause infection, dehydration, and electrolyte imbalance. Death usually occurs within 2 weeks. Damage to the gastrointestinal tract is one of the primary causes of morbidity and mortality following radiation exposure.

Cardiovascular (CV)/ Central Nervous System (CNS) syndrome: Death occurs within 3 days. Death likely is due to collapse of the circulatory system as well as increased pressure in the confining cranial vault as the result of increased fluid content caused by edema, vasculitis, and meningitis.


The four stages of ARS are:

  1. Prodromal stage (N-V-D stage)
  2. Latent stage
  3. Manifest illness stage
  4. Recovery or death

Symptoms for GI syndrome during four stages:

  1. Stage lasts about 2 days. Onset occurs within a few hours after exposure. Symptoms are: Anorexia, severe nausea,vomiting, cramps, diarrhea
  2. Stage lasts less than 1 week. Symptomes are: Stem cells in bone marrow and cells lining GI tract are dying, although patient may appear and feel well.
  3. Death is due to infection, dehydration, and electrolyte imbalance. Death occurs within 2 weeks of exposure. Symptomes are: Malaise, anorexia, severe diarrhea, fever, dehydration, and electrolyte imbalance.
  4. the LD100 (the dose necessary to kill 100% of the exposed population) is about 10 Gy (1000 rads)


The full GI syndrome will usually occur with a dose greater than approximately 10 Gy* (1000 rads) although some symptoms may occur as low as 6 Gy or 600 rads.

The full Bone marrow syndrome will usually occur with a dose between 0.7 and 10 Gy (70 – 1000 rads) though mild symptoms may occur as low as 0.3 Gy or 30 rads

The full CV/CNS syndrome will usually occur with a dose greater than approximately 50 Gy (5000 rads) although some symptoms may occur as low as 20 Gy or 2000 rads.

* - The Gray (Gy) is a unit of absorbed dose and reflects an amount of energy deposited into a mass of tissue (1 Gy = 100 rads). In this document, the referenced absorbed dose is that dose inside the patient’s body (i.e., the dose that is normally measured with personal dosimeters).


Administration of radioprotectants before irradiation decreases damage to healthy cells, while not protecting cancerous tissues.


The diagnosis of ARS can be difficult to make, because ARS causes no unique disease. Also, depending on the dose, the prodromal stage may not occur for hours or days after exposure, or the patient may already be in the latent stage by the time they receive treatment, in which case the patient may appear and feel well when first assessed.

If you were exposed to high dose of radiation or have the abovementioned symptoms (like nausea, vomiting, diarrhea, and itching, reddening or blistering of the skin) of unknown nature, contact your healthcare provider.

Blood samples have to be taken as soon as possible after the radiation exposure.


The treatment of the gastrointestinal subacute syndrome remains difficult and unsuccessful after exposure to total body doses greater than 8-10 Gy.

Supportive therapy to prevent infection and dehydration may be effective, if restoration or repopulation of the intestinal and bone marrow stem cells does occur. In addition, bone marrow transplantation may improve the prospect of treating the hemopoietic syndrome. Anaesthetics and antiemetics are administered to counter the symptoms of exposure, as well as antibiotics for countering secondary infections due to the resulting immune system deficiency.

Treatment has to be performed by a healthcare professional.


  • Centers for Control & Prevention (SDC)