Coma Causes & Risks

Causes

Normally, information from a person’s surroundings is passed from the brainstem into the cerebrum. This feedback allows a person to be conscious of and react to his environment. When this system breaks down and a person is no longer able to respond, a coma can result.

Brainstem and Cerebrum

A coma may be caused by:

Severe head injury, most commonly from:
- Motor vehicle accidents
- Violence
- Falls
Primary brain disorder
- Brain tumor
- Brain hemorrhage or stroke
- Brain infection
Lack of oxygen to the brain due to:
- Very high blood pressure
- Very low blood pressure or shock
- Cardiac arrest
- Severe seizures
Severe general illness:
- Severe bodily infections
- Severe acute liver or kidney failure
- High carbon dioxide levels
- Carbon monoxide poisoning
- Toxicity from poisons, medication, alcohol , or drugs
- Abnormal hormone levels, such as from the thyroid or adrenal gland
- Abnormal blood chemistries, such as sodium or calcium
- Very low or very high levels of blood sugar
- Very low or very high body temperatures
- Severe nutrient deficiency
- Liver failure
- Kidney failure
- Inherited metabolic diseases

Risk Factors

Risk factors for coma include:

Severe illness
Diabetes
Liver, kidney, or cardiovascular disease
Tendency to have blood clots
Exposure to poisonous substances (eg, carbon dioxide)
Cancer and chemotherapy

Risk factors for brain injury include:

Age: 5 years or younger, 15-24 years old, and 75 years or older
Sex: male
Traveling in a vehicle at a high rate of speed or at night
Lack of sleep
A previous head injury

Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition. Copyright © 2026 EBSCO Publishing All rights reserved.