Coma

A coma happens when you’re unconscious, unresponsive and unaware of what’s going on around you. You can’t wake up, think, talk, respond to a conversation or react to the feeling of pain.

There are several possible causes, like brain injuries, stroke, complications from substance use or infections, among others.

A coma is a medical emergency that requires immediate attention. It’s a common reason people end up in emergency rooms.

Comas typically don’t last longer than a couple of weeks. Severe brain injuries may lead to a persistent vegetative state or possible brain death. Delaying treatment may lead to serious complications or life-threatening outcomes.

Types of coma

The types vary based on the cause:

• Anoxic brain injury: Caused by a lack of oxygen to your brain (like after a cardiac arrest or drowning)
• Diabetes-related: Due to very low or very high blood sugar levels
• Medically induced: A controlled coma in a medical setting to help the brain rest
• Toxic-metabolic encephalopathy: From too much or too little of certain chemicals in your body (like overdose)
• Trauma-induced: Caused by a head injury

Symptoms of a coma

Signs and symptoms may include:

• Closed eyes
• Pupils that don’t respond to light when the eyes are opened
• No movement except reflexes
• No response to pain or loud noises
• No speech, communication or awareness
• Slow, irregular or gasping breathing patterns
• Loss of consciousness

These can vary from person to person. While many signs are common, some people may move differently. Comas also range in severity.

Causes of a coma

A coma occurs when something disrupts how your brain works. This could happen to your:

• Brainstem’s reticular activating system: A network of nerve cells (neurons) that keeps you awake
• Cerebral hemispheres: The two largest areas of your brain that help you think

Common causes may include:

• A lack of oxygen or blood flow to the brain
• Brain tumors
• Extreme body temperatures (high or low)
• Head injuries
• Infection (meningitis or encephalitis)
• Metabolic issues (blood sugar levels, liver or kidney failure)
• Seizures (status epilepticus)
• Stroke
• Substance overdose (opioids, alcohol)

Risk factors

Anyone can fall into a coma. But you might be more at risk if you have:

• A substance use disorder
• Diabetes (with very high or low blood sugar)
• Epilepsy or other seizure disorders
• Heart problems
• High blood pressure or cholesterol
• Low thyroid levels

Your risk also goes up if you skip a helmet during activities like biking, motorcycling or contact sports, or if you don’t wear a seatbelt in the car.

Complications of a coma

If you’re in a coma, you can’t care for yourself. You’ll need around-the-clock medical support. You might need tube feeding, a urinary catheter to collect pee and a ventilator to help you breathe.

Complications from being in a coma or receiving coma-related care may include:

• Bedsores
• Blood clots
• Delirium
• Infections, like pneumonia from a ventilator or UTIs from a catheter
• Muscle loss and weakness

How doctors diagnose a coma

If you’re unconscious, providers will immediately check your vitals, which include your breathing, heart rate and blood pressure. They may offer immediate treatment, like sugar for low blood sugar or opioid reversal medication if they suspect an overdose.

Your providers will perform a physical and neurological exam. They’ll use the Glasgow Coma Scale to identify the severity. The GCS measures three categories:

• Eye response (1 to 4)
• Motor response (1 to 6)
• Verbal response (1 to 5)

A total score ranges from 3 to 15. A score of 15 means fully alert, and 8 or below usually indicates a coma.

What tests diagnose a coma?

Tests help confirm a diagnosis and find the cause. Common tests include:

• Lab tests (blood, urine, spinal fluid) to check for infections, toxins, organ issues or imbalances
• Imaging (CT or MRI) to look for brain injuries or damage
• EEG to track brain activity and seizures
• EKG to detect heart rhythm problems

Your provider may need other tests based on the situation. A healthcare provider can explain what’s being done and why.

Disorders of consciousness

Severe brain injuries can lead to disorders of consciousness. This describes how awake and aware a person is. A provider might use these terms to describe a diagnosis better:

• Vegetative state: Awake but unaware of yourself or your surroundings
• Persistent vegetative state: Awake but unaware, and lasting more than one month
• Minimally conscious state: Limited, inconsistent signs of awareness
• Confusional state: Some awareness, but disoriented and confused
• Coma: Loss of consciousness, unaware and unresponsive
• Brain death: Complete and irreversible loss of all brain function

How is a coma treated?

Treatment may include:

• Making sure you’re safe: Your care team will help you breathe using a ventilator and keep your heart beating by giving you fluids through an IV.
• Handling emergencies: Depending on the cause, you may need IV sugar (dextrose) for low blood sugar, an injection of naloxone for an overdose or medications for seizures.
• Managing the cause: You may need antibiotics for infections, surgery for head injuries or medicine for heart problems, among other treatments, to prevent complications.

Your care team will watch how your body responds. They may use the Glasgow Coma Scale to check your progress.

Coma recovery scale

As you recover, your body and brain need time to heal. You may not be able to talk or move right away. But even small signs of awareness, like following something with your eyes, are important. Healthcare providers use the Coma Recovery Scale to track these signs.

The scale measures:

• Body movement
• Eye movement
• Sounds and speech
• Touch and pain responses

This scale helps your care team see how you’re progressing. It can help them choose the right treatments to support your recovery.

What can I expect if I am in a coma?

Being in a coma means you’re not conscious, so you don’t know you’re in a coma. You don’t show any signs of awareness of the world around you, and you can’t react to your environment or your body’s needs. Depending on the depth of the coma, you may still have some reflex responses. But these vary from case to case.

How long does a coma last?

A coma can be very brief and last only a few minutes, or it can last as long as one to two weeks. Unfortunately, death is a possible complication. This is more likely with severe injuries, serious illness or delayed medical care.

Most comas don’t last more than a few weeks. People often either wake up or shift into a different state of reduced consciousness.

The outcome depends on many factors. A healthcare provider familiar with the case is the best person to explain what to expect.

How to make sure your wishes are followed if you can’t speak for yourself

If you’re ever in a coma, loved ones will have to make medical decisions for you. Talking with them ahead of time about your wishes and putting those wishes in writing can help ensure your choices are respected. Legal documents like advance directives can guide your care if you’re unable to decide for yourself.

Can I hear or remember things that happened while I was in a coma?

It’s possible. Some people in a coma can hear what’s happening around them and even remember parts of it later. But this varies a lot and is hard to predict. A healthcare provider can help you understand what this might mean for you or your loved one’s recovery.