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Symptoms
By Mayo Clinic staffThe 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.
Absorbed dose and duration of exposure
The absorbed dose of radiation is measured in a unit called a gray (Gy). An example of a safe radiation exposure is a conventional dental X-ray, which results in an absorbed dose to the jaw of about 0.0025 Gy. A typical whole-body computerized tomography (CT) scan, a type of X-ray exam, results in an average whole-body dose of about 0.012 Gy.
Signs and symptoms of radiation sickness usually appear with absorbed doses to the whole body of at least 1 Gy. Doses greater than 8 Gy are generally not treated successfully and usually result in death within two days to two or three weeks depending on the 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 the onset of these symptoms is, in fact, a relatively reliable indicator of how much radiation a person has absorbed.
After the initial onset of signs and symptoms, a person with radiation sickness then experiences a brief period of a few days with no apparent illness. This period precedes the onset of signs and symptoms indicating more serious illness.
Mild radiation sickness
Signs and symptoms resulting from an acute absorbed dose of 1 to 2 Gy may include:
- Nausea and vomiting within 24 to 48 hours
- Headache
- Fatigue
- Weakness
Moderate radiation sickness
With an acute absorbed dose of 2 to 3.5 Gy, a person may experience:
- Nausea and vomiting within 12 to 24 hours
- Fever
- Hair loss
- Infections
- Vomiting blood
- Bloody stool
- Poor wound healing
- Any signs and symptoms associated with a lower absorbed dose
Moderate radiation sickness can be fatal to those most sensitive to radiation exposure.
Severe radiation sickness
An absorbed dose of 3.5 to 5.5 Gy can result in the following signs and symptoms:
- Nausea and vomiting less than one hour after exposure to radiation
- Diarrhea
- High fever
- Any signs and symptoms associated with a lower absorbed dose
Severe radiation sickness is fatal about half the time.
Very severe radiation sickness
A person with an absorbed dose greater than 5.5 to 8 Gy can have the following signs and symptoms:
- Nausea and vomiting less than 30 minutes after exposure to radiation
- Dizziness
- Disorientation
- Low blood pressure (hypotension)
- Any signs and symptoms associated with a lower absorbed dose
Very severe radiation sickness is often fatal.
