Coma is a state of prolonged unconsciousness that can be caused by a variety of problems — traumatic head injury, stroke, brain tumor, drug or alcohol intoxication, or even an underlying illness, such as diabetes or an infection.
Coma is a medical emergency. Swift action is needed to preserve life and brain function. Doctors typically order a battery of blood tests and a brain CT scan to try to determine what's causing coma so that proper treatment can begin.
Comas seldom last longer than several weeks. People who are unconscious for longer than that can transition to a persistent vegetative state. Depending on the cause of coma, people who are in a persistent vegetative state for more than three years are extremely unlikely to awaken.
The signs and symptoms of coma commonly include:
When to see a doctor
Many types of problems can cause coma. Some examples are:
Although many people gradually recover from coma, others enter a vegetative state or die.
Complications that may develop during coma include pressure sores, bladder infections and pneumonia.
Preparing for your appointment
Coma is an emergency medical condition. If you are with a person who develops signs and symptoms of coma, call 911 or your local emergency number immediately.
When you arrive at the hospital, emergency room staff will urgently need as much information as possible about what happened before the coma. On the way to the hospital, try to pull together answers to the following questions:
Tests and diagnosis
Because people in coma can't express themselves, doctors must rely on physical clues and information provided by families and friends. Be prepared to answer a number of questions about:
A spinal tap (lumbar puncture) can check for signs of infections. During a lumbar puncture procedure, a doctor inserts a needle into your spinal canal, measures the pressure and collects fluid for analysis. The entire procedure usually takes about 10 minutes.
Treatments and drugs
Coma is a medical emergency, and attention first is given to maintaining respiration and circulation. Assistance with breathing, administration of fluids and blood, and other supportive care may be necessary.
Emergency personnel may administer glucose or antibiotics intravenously, even before blood test results return, on the chance that the person is in diabetic shock or has an infection affecting the brain.
Treatment varies, depending on what's causing the coma. Sometimes surgery is needed to relieve the pressure due to brain swelling. Other treatments may focus on addressing an underlying disease, such as diabetes, kidney failure or liver disease.
Sometimes the cause of coma can be completely reversed and the person will regain normal function. But if the brain damage is severe, the person may sustain permanent disabilities or may never regain consciousness.
Last Updated: 2010-05-08
© 1998-2014 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved. A single copy of these materials may be reprinted for noncommercial personal use only. "Mayo," "Mayo Clinic," "MayoClinic.com," "Mayo Clinic Health Information," "Reliable information for a healthier life" and the triple-shield Mayo logo are trademarks of Mayo Foundation for Medical Education and Research.
Terms and conditions of use