Overview

Radiation sickness is damage to your body caused by a large dose of radiation often received over a short period of time (acute). The amount of radiation absorbed by the body — the absorbed dose — determines how sick you'll be.

Radiation sickness is also called acute radiation sickness, acute radiation syndrome or radiation poisoning. Common exposures to low-dose radiation, such as X-ray or CT examinations, don't cause radiation sickness.

Although radiation sickness is serious and often fatal, it's rare. Since the atomic bombings of Hiroshima and Nagasaki, Japan, during World War II, most cases of radiation sickness have occurred after nuclear industrial accidents, such as the 1986 fire that damaged the nuclear power plant at Chernobyl, Ukraine.

Symptoms

The severity of signs and symptoms of radiation sickness depends on how much radiation you've absorbed. How much you absorb depends on the strength of the radiated energy and the distance between you and the source of radiation.

Signs and symptoms also are affected by the type of exposure — such as total or partial body and whether contamination is internal or external — and how sensitive to radiation the affected tissue is. For instance, the gastrointestinal system and bone marrow are highly sensitive to radiation.

Absorbed dose and duration of exposure

The absorbed dose of radiation is measured in a unit called a gray (Gy). Diagnostic tests that use radiation, such as an X-ray, result in a small dose of radiation — typically well below 0.1 Gy — focused on a few organs or small amount of tissue.

Signs and symptoms of radiation sickness usually appear when the entire body receives an absorbed dose of at least 1 Gy. Doses greater than 10 Gy to the whole body are generally not treatable and usually lead to death within two days to two weeks, depending on the dose and duration of the exposure.

Initial signs and symptoms

The initial signs and symptoms of treatable radiation sickness are usually nausea and vomiting. The amount of time between exposure and when these symptoms develop is an indicator of how much radiation a person has absorbed.

After the first round of signs and symptoms, a person with radiation sickness may have a brief period with no apparent illness, followed by the onset of new, more-serious symptoms.

In general, the greater your radiation exposure, the more rapid and more severe your symptoms will be.

Signs and symptoms of radiation sickness
Mild exposure
(1-2 Gy)
Moderate exposure
(2-6 Gy)
Severe exposure
(6-9 Gy)
Very severe exposure
(10 Gy or higher)
Based on Radiation exposure and contamination. Merck Manual Professional Edition.
Nausea and vomiting Within 6 hours Within 2 hours Within 1 hour Within 10 minutes
Diarrhea -- Within 8 hours Within 3 hours Within 1 hour
Headache -- Within 24 hours Within 4 hours Within 2 hours
Fever -- Within 3 hours Within 1 hour Within 1 hour
Dizziness and disorientation -- -- Within 1 week Immediate
Weakness, fatigue Within 4 weeks Within 1-4 weeks Within 1 week Immediate
Hair loss, bloody vomit and stools, infections, poor wound healing, low blood pressure -- Within 1-4 weeks Within 1 week Immediate

When to see a doctor

An accident or attack that causes radiation sickness would no doubt cause a lot of attention and public concern. If such an event occurs, monitor radio, television or online reports to learn about emergency instructions for your area.

If you know you've been overexposed to radiation, seek emergency medical care.

Causes

Radiation is the energy released from atoms as either a wave or a tiny particle of matter. Radiation sickness is caused by exposure to a high dose of radiation, such as a high dose of radiation received during an industrial accident. Common exposures to low-dose radiation, such as X-ray exams, don't cause radiation sickness.

Sources of high-dose radiation

Possible sources of high-dose radiation include the following:

  • An accident at a nuclear industrial facility
  • An attack on a nuclear industrial facility
  • Detonation of a small radioactive device
  • Detonation of a conventional explosive device that disperses radioactive material (dirty bomb)
  • Detonation of a standard nuclear weapon

Radiation sickness occurs when high-energy radiation damages or destroys certain cells in your body. Regions of the body most vulnerable to high-energy radiation are cells in the lining of your intestinal tract, including your stomach, and the blood cell-producing cells of bone marrow.

Complications

Radiation exposure that causes immediate radiation sickness significantly increases a person's risk of developing leukemia or cancer later in life.

Having radiation sickness could also contribute to both short-term and long-term mental health problems, such as grief, fear and anxiety about:

  • Experiencing a radioactive accident or attack
  • Mourning friends or family who haven't survived
  • Dealing with the uncertainty of a mysterious and potentially fatal illness
  • Worrying about the eventual risk of cancer due to radiation exposure

Prevention

In the event of a radiation emergency, stay tuned to your radio or television to hear what protective actions local, state and federal authorities recommend. Recommended actions will depend on the situation, but you will be told to either stay in place or evacuate your area.

Shelter in place

If you're advised to stay where you are, whether you're at home or work or elsewhere, do the following:

  • Close and lock all doors and windows.
  • Turn off fans, air conditioners and heating units that bring air in from outside.
  • Close fireplace dampers.
  • Bring pets indoors.
  • Move to an inner room or basement.
  • Stay tuned to your emergency response network or local news.

Evacuate

If you're advised to evacuate, follow the instructions provided by your local authorities. Try to stay calm and move quickly and in an orderly manner. In addition, travel lightly, but take supplies, including:

  • Flashlight
  • Portable radio
  • Batteries
  • First-aid kit
  • Necessary medicines
  • Sealed food, such as canned foods, and bottled water
  • Manual can opener
  • Cash and credit cards
  • Extra clothes

Be aware that most emergency vehicles and shelters won't accept pets. Take them only if you're driving your own vehicle and going someplace other than a shelter.