What is a coma?
When someone is in a coma, they are unconscious, they do not respond, and they cannot be woken up. A coma is a medical emergency and the person in the coma will need immediate treatment in hospital.
Someone who is in a coma is alive but completely unresponsive to the world around them. There is very little activity in their brain.
Some people in a coma can breathe on their own but others will need help. They won’t be able to cough or swallow and they won’t respond to pain, light or sound. Their eyes will be closed and they won’t be able to move or communicate.
There are different levels, or depths, of coma. The hospital will measure the depth of the coma based on the person’s responses, how long they have been in a coma and how well their body is functioning. They do this to track the person’s level of consciousness over time.
Some people may become more alert and wake up but show no signs of awareness. This is called post-coma unresponsiveness (previously called persistent vegetative state). People can stay like this for a long time and may improve, but they are unlikely to make a full recovery.
What are the most common causes of coma?
The causes of coma include:
- brain injuries caused by an accident or violence
- a stroke or lack of oxygen to the brain
- diabetes, if sugar levels get much too high or too low
- an infection such as meningitis or encephalitis
- a seizure
- overdosing on drugs or medicines
- being exposed to a toxic substance, such as carbon monoxide
- diseases of the central nervous system
Sometimes people are put into a medically induced coma with medicines. This helps their brain to keep functioning after an injury and saves the patient from feeling extreme pain.
What care does someone in a coma need?
Someone in a coma needs intensive care in hospital. They may need help with breathing, they will be fed through a tube and they will receive blood and fluids through a drip inserted into the vein. The cause of their coma will also need to be treated to prevent further brain damage.
They will need medical support to stop their body deteriorating and to prevent complications such as pressure sores and ulcers, infections or blood clots in the legs, including deep vein thrombosis (DVT). Their limbs will need to be exercised gently to prevent them from getting tight. They may also need medicine to calm them down if they get restless.
Although it has not been scientifically proven, many families of people who have been in a coma say that talking to them, playing their favourite music and stimulating them can help them to wake up.
What is the expected outcome of a coma?
Comas usually don’t last longer than 4 weeks, although cases have been recorded where people stay in a coma for several years. When someone comes out of a coma, they become more aware and regain consciousness gradually. After they wake up, they might be very confused about the day and time, where they are and who they are.
Their long-term expected outcome (prognosis) will depend on the brain injury that caused the coma. Some people, such as people who were in a diabetic coma, will make a full recovery. Others may have permanent brain damage and will need therapy and support for the rest of their lives.
People with post-coma unresponsiveness can be in this state for months or years. They may gradually pass into a minimally conscious state, where they are more aware and may be able to communicate.
Unfortunately, some people never recover from a coma. If the coma lasts more than a few weeks, their family may be asked to make decisions about whether to continue medical support. It’s easier to make the decision if families members have discussed their wishes earlier.
Resources and support
You can find more information about brain injury and coma from the following organisations:
- Brain Foundation
- Synapse (Australia's brain injury organisation)
- Brain Injury Australia
If you know someone in a coma, you can register their details on the Australian Register of Disorders of Consciousness (ARDOC).
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Last reviewed: May 2021