Acute radiation syndrome (ARS), also known as radiation sickness, is a constellation of symptoms associated with short term exposure to high doses of radiation. Some people recover from radiation exposure, while others may die in weeks or months. The chances for recovery depend on the nature of radiation and the dosage. Prevention of acute radiation syndrome involves avoidance of sources of high dose radiation.
To develop acute radiation syndrome, most of someone's body needs to be exposed to a large amount of penetrating radiation in a short period of time. A classic example of a cause of ARS is the detonation of a nuclear bomb. People who are not adequately shielded when the explosion occurs will die instantly or be exposed to levels of radiation which can lead to radiation sickness. Nuclear accidents can also lead to acute radiation syndrome. First responders such as police and fire personnel are often at increased risk because they enter danger areas before they are entirely safe.
There are four phases of this syndrome. The first phase, known as the prodromal phase, involves early symptoms such as nausea, vomiting, and diarrhea. Then, the patient starts to feel better for hours or days, and may seem relatively healthy in the latency phase. This is followed by the manifest illness or critical phase, in which the patient experiences neurological and gastrointestinal symptoms like seizures, coma, confusion, vomiting, and diarrhea. In addition, the patient's bone marrow is damaged, leading to infections, internal bleeding, and anemia.
The fourth phase of acute radiation syndrome is death or recovery. Patients can die because the dose of exposure is too high or because their bodies were simply not able to cope with the radiation damage. People who recover can be at risk for health complications later in life. Commonly radiation sickness leads to damage of the skin and hair which can endure for life. Radiation burns on the skin, for example, can scar and will be visible after recovery.
Treatment for patients who experience acute radiation syndrome is focused on supportive care. This can include hydration to help patients retain fluid levels if they are vomiting, cold baths for patients who develop fevers, and pain management for patients who experience severe pain as a result of radiation damage. Because events which can lead to radiation sickness are fairly rare, many doctors have limited firsthand experience treating ARS and they may require assistance from experts who respond to radiation disasters.