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Medically reviewed by Last updated on Dec 14, 2022.


Coma is a state of prolonged loss of consciousness. It can have a variety of causes, including traumatic head injury, stroke, brain tumor, or drug or alcohol intoxication. A coma may even be caused by an underlying illness, such as diabetes or an infection.

Coma is a medical emergency. Quick action is needed to preserve life and brain function. Health care providers typically order a series of blood tests and a brain scan to try to learn what's causing the coma so that proper treatment can begin.

A coma doesn't usually last longer than several weeks. People who are unconscious for a longer time might transition to a lasting vegetative state, known as a persistent vegetative state, or brain death.


The symptoms of a coma commonly include:

When to see a doctor

A coma is a medical emergency. Seek immediate medical care for the person in a coma.


Many types of problems can cause a coma. Some examples are:


Although many people gradually recover from a coma, others enter a persistent vegetative state or die. Some people who recover from a coma end up with major or minor disabilities.

During a coma, bedsores, urinary tract infections, blood clots in the legs and other problems may develop.


Because people in a coma can't express themselves, health care providers must rely on physical clues and information provided by families and friends. Be prepared to provide information about the affected person, including:

Physical exam

The exam is likely to include:

Laboratory tests

Blood samples typically are taken to check for:

A spinal tap, also known as a lumbar puncture, can check for signs of infections in the nervous system. During a spinal tap, a health care provider inserts a needle into the spinal canal and collects a small amount of fluid for analysis.

Brain scans

Imaging tests help pinpoint areas of brain injury. Tests might include:


A coma is a medical emergency. Health care providers typically first check the affected person's airway and help maintain breathing and circulation. Providers might give breathing assistance, medicines through a vein and other supportive care.

Treatment depends on the cause of the coma. A procedure or medicines to relieve pressure on the brain due to brain swelling might be needed. Emergency responders might give glucose or antibiotics through a vein in the arm. These may be given even before blood test results return in cases of very low blood sugar or an infection affecting the brain.

If the coma is the result of drug overdose, health care providers typically give medicines to treat the condition. If the coma is due to seizures, medicines can control seizures. Other treatments might focus on medicines or therapies to address an underlying disease, such as diabetes or liver disease.

Sometimes the cause of a coma can be completely reversed, and the affected person regains function. Recovery usually occurs gradually. A person with severe brain damage might have permanent disabilities or never regain consciousness.

Preparing for an appointment

A coma is an emergency medical condition. If you are with a person who develops symptoms of a coma, call 911 or emergency medical help immediately.

When you arrive at the hospital, emergency room staff will need as much information as possible from family and friends about what happened to the affected person before the coma. You might be asked the following questions while riding in the ambulance:

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