Many types of problems can cause a coma

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

Traumatic brain injuries. These are often caused by traffic collisions or acts of violence.

Stroke. Reduced or interrupted blood supply to the brain (stroke), can result from blocked arteries or a burst blood vessel.

Tumors. Tumors in the brain or brainstem can cause a coma.

Diabetes. Blood sugar levels that become too high (hyperglycemia) or too low (hypoglycemia) can cause a coma.

Lack of oxygen. People who have been rescued from drowning or those who have been resuscitated after a heart attack might not awaken due to lack of oxygen to the brain.

Infections. Infections such as encephalitis and meningitis cause swelling of the brain, spinal cord or the tissues that surround the brain. Severe cases of these infections can result in brain damage or a coma.

Seizures. Ongoing seizures can lead to a coma.

Toxins. Exposure to toxins, such as carbon monoxide or lead, can cause brain damage and a coma.

Drugs and alcohol. Overdosing on drugs or alcohol can result in a coma.


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

Complications can develop during a coma, including pressure sores, urinary tract infections, blood clots in the legs and other problems.


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