A coma is a state of unconsciousness where a person is unresponsive and cannot be woken.
A person can also be in a coma as a result of alcohol intoxication. Extreme changes in blood sugar levels in people with diabetes - very low blood glucose levels (hypoglycaemia) or very high blood glucose levels (hyperglycaemia) - can also cause coma.
You may find the following information useful if you have a friend or a loved one who is in a coma. It covers:
Someone who is in a coma has minimal brain activity. They're alive but can't move or be woken. Their potential for recovery will depend on the cause of the coma.
A person in a coma will often be unresponsive to their environment. They may not be able to hear voices or feel pain. However, a person in a coma may have some awareness of their surroundings. Every coma experience is unique.
Occasionally, a person in a coma may open their eyes, grimace or make a noise. They may not be aware of these movements or have any control over them.
Being in a coma means the person has a low level of consciousness. Their level of consciousness will depend on how much of their brain is functioning, which may change over time.
For example, initially a person may be in a very deep coma, where they're unresponsive to pain, before gradually recovering to a lighter coma, where they respond to pain. They may continue improving and eventually they may become aware of their surroundings and begin to communicate.
The ability to make a clearly conscious response to external instructions indicates that the person is no longer in a coma.
Doctors score a person's level of consciousness using a tool called the Glasgow Coma scale. This level is monitored constantly for signs of improvement or deterioration. The Glasgow Coma Scale assesses three things. They are:
A higher score on the scale suggests that less brain function has been lost. A score of eight or less is often used to mean that someone is in a relatively deep coma.
While someone in a deeper coma generally has a poorer outcome, the cause of the coma is important in determining their recovery. For example, a young person who took an alcohol or drug overdose may be deeply comatose to begin with, but may make a very good recovery with the appropriate medical care.
A person in a coma may be unable to maintain normal body function. For example, they may not be able to breathe unaided and their blood pressure may be unstable.
Caring for a person in a coma involves ensuring that their condition is stable and their body functions, such as breathing and blood pressure, are supported, while the underlying condition is treated.
Healthcare staff will try to prevent infections, provide good nutrition and prevent bedsores by moving the person’s position regularly.
In the early stages, most people in a coma will be cared for in an intensive care unit (ICU).
The experience of being in a coma differs from person to person, and also depends on how deep the coma is.
Some people remember events that happened around them while they were in a coma, while others don't. Most memories are likely to relate to the period when the person comes out of the coma.
Some people have reported feeling enormous reassurance from the presence of a loved one when coming out of a coma.
When visiting a friend or loved one in a coma, you may find the advice below helpful.
A coma can last hours, days or even months. Some people remain in a coma for years, although this is unusual.
Recovery depends on how much of the person’s brain has been affected by the underlying condition or injury. Generally, the longer the person has been in a coma, the poorer the outlook.
People don't usually suddenly 'wake up' from a coma, but tend to come round gradually and regain brain function over time. When a person comes out of a coma, they may be agitated and confused. They may need to be sedated for their own safety.
Some people will make a full recovery and be completely unaffected by the coma. Others may not be able to do some of the things they used to do, and may need to have physiotherapy, occupational therapy and psychotherapy during a period of rehabilitation. They may need care for the rest of their lives.
Some people who recover from a coma will be in a vegetative state. They may be able to open their eyes and appear to be awake, and they may recover basic functions, such as breathing unaided and controlling their blood pressure. However, someone who is in a vegetative state will have lost a substantial amount of brain function and be unaware of their surroundings.
For further information and support from healthcare professionals and the families of people in a coma, you may find the following resources helpful:
Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.