How Long Can the Brain Be without Oxygen before Brain Damage?

Erin J. Hill

In general, the brain can withstand up to three to six minutes without oxygen before brain damage occurs, but this may vary from person to person. If the brain goes without oxygen longer than this, serious and often irreversible damage is likely to take place. After ten minutes, severe neurological damage has generally occurred. Very few people regain any cognitive function after the brain has gone 15 or more minutes without oxygen.

The brain can be deprived of oxygen for three to six minutes before permanent damage occurs, though this can be extended in scenarios that involve a sudden immersion in cold water.
The brain can be deprived of oxygen for three to six minutes before permanent damage occurs, though this can be extended in scenarios that involve a sudden immersion in cold water.

Since the brain cannot retain oxygen on its own, it relies on a steady supply provided through the bloodstream. Brain death can occur rapidly as cells begin to die off without any oxygen stores or new oxygen circulating to the brain. Almost immediately after oxygen intake has ceased, brain cells begin to perish. The brain usually only lasts a few short minutes without oxygen before damage occurs on some level.

Cognitive brain function is rarely regained after more than 15 minutes without oxygen.
Cognitive brain function is rarely regained after more than 15 minutes without oxygen.

Occasionally, the brain can last longer without oxygen before brain damage becomes severe, but this usually requires very specific circumstances. It usually requires that oxygen cessation happen at the same time as the body becomes cold very rapidly, such as if a person falls into icy water and begins to drown. Young children have been known to go up to half an hour without oxygen and still survive in situations like this.

The brain is unable to retain its own oxygen.
The brain is unable to retain its own oxygen.

In most cases, brain damage is irreversible when it occurs due to long-term oxygen deprivation. For this reason, during cases of illness or injury where breathing ceases, it is vital that emergency personnel work to provide steady oxygen flow to the heart and brain. This can be done through artificial means or by getting the patient to breathe again on his or her own. Death is usually declared once the brain has gone more than 15 minutes without oxygen.

Brain damage can be a potentially devastating medical issue.
Brain damage can be a potentially devastating medical issue.

Although the brain can only go a few minutes without oxygen before some type of brain damage occurs, patients can often regain cognitive function if treated quickly. The severity of long-term complications is usually in direct correlation with the length of time the person has gone without oxygen. A patient’s exact outcome and level of damage may also depend on why he or she stopped breathing to begin with.

Some patients can regain cognitive functions if their oxygen-deprived brain is treated promptly.
Some patients can regain cognitive functions if their oxygen-deprived brain is treated promptly.

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Discussion Comments


I was rushed into hospital last July 2018, after having repeated seizure's, at home, in town they would just happen without warning. I'd not had anything like this before, only light dizzy spells, feeling weak and palpitations.

The day before I was rushed to hospital I'd had (worst run of them) another nine seizures in one day, that my doctor just put down to panic attacks/stress.

The following morning I woke feeling rather ill and collapsed in my daughters room, ambulance/paramedics came at first refused to take me (this didn't go down well with my family) eventually they did (good thing they did) after being taken in and just left in a wheelchair in the waiting area, 2 minutes later I went into full cardiac arrest lucky another paramedic noticed and rushed me to resuscitation room, where I was without oxygen to my brain for about five minutes, and needed to be shocked with the defibrillator twice.

Long story short, I was rushed to another hospital for emergency surgery to have a temporary heart pacing wire fitted, kept in the hospital nine days where in that time I needed to have a permanent pacemaker fitted, which still might need to be upgraded to a ICD in case my heart stops again, and put on Beta-blockers (Nadolol). They eventually diagnosed me with condition(s) called Long QT Syndrome Torsades de Pointes, COPD, and I also have asthma.

I have to be aware of what medications I can't take. At last count there were around 127 types of meds I cannot take. I am still learning about my illness and see my specialist very often. The slightest startling, stress etc. can affect my heart.

If anyone else has it or heard of it and knows some good websites to look at please tell me. Thank you.


My mum had a seizure and cardiac arrest brought on by alcoholism. She was down for 20 minutes, but the medical staff shocked her five times and got her back.

After treatment in ITC and HDU for four weeks, she is physically OK, but her short term memory has gone. She doesn't recognize people and forgets what you told her five minutes ago. This is heartbreaking to watch and I wonder if there is a chance she could recover as now needs to go into a 24 hour care home. She cannot keep her balance when standing and keeps falling. Can anyone advise, please?


It seems a lot of posters are confused about why brain damage is delayed in a cold environment. The cold environment essentially acts to slow down time within the body. Cold temperatures slow the rates of chemical reactions down. In the body these consist of the many reactions like enzymatic activity and essentially all other cellular processes. Thus, for a given amount of time, the brain needs much less oxygen for a given period of time under very cold circumstances. Scientists understand the concept well.

Additionally, this concept has been employed as a surgical tool as well (a blood machine that dramatically lowers the temperature of the blood and then returns the cooled blood to the patient). This method greatly prevents brain damage and also gives the surgeon a larger time window which, is especially important in complex and lengthy surgical interventions.


@turquoise-- That's a good question, I'm not sure if it works or not.

Like @feasting said though, there are cases of people who fell into extremely cold water, was without oxygen for a good number of minutes and recovered without any brain damage.

I think scientists are still studying how this is possible. This might become a new first aid technique in these sort of situations. Although I don't think it has been recognized as a precautionary measure or treatment yet.

I've heard that if you apply something cold like ice to people's eyes when their heart has stopped, you can delay brain damage. Is this true?

I have to have an MRI once a year, and I have to hold my breath several times during the scan. Sometimes, it is just for 30 seconds, but other times, it is for nearly a minute.

After awhile, I start to panic a little. I lie there thinking that surely the technician will tell me to breathe soon, but sometimes, he doesn't, and I just can't take it anymore!

I guess the lack of oxygen to my brain is making it send signals to my diaphragm, because I feel it start to jump a little. I find myself taking tiny little breaths and exhaling the smallest amount possible, hoping that it will be imperceptible to the technician.


I find it amazing that a person who is dunked into cold water for several minutes can survive. I wonder if they exhibit brain damage symptoms, though.

I guess that extreme cold preserves the body somehow. I know that my lungs seem to go into shock even when I enter a swimming pool in early summer and the water is still pretty cool. This makes it hard to breathe, and it feels as if my lungs are paralyzed.


@Oceana – I've read that there are tricks to this. I believe the world record for breath holding is 19 minutes, which seems an insane amount of time.

To keep the lack of oxygen from causing brain damage, people hyperventilate. As the carbon dioxide is building up in their bodies, they have to have a way to expel it, so they do these quick little bursts of hyperventilation to remove it from their lungs.

I would never try this, because even with the tricks, there is still a big risk of brain damage. It would also be a very uncomfortable thing to do.


How do some people manage to hold their breath for several minutes? I've heard that there are actual competitions to see who can hold their breath the longest. How can they do this without suffering damage to the brain?


My friend had a heart attack and her heart stopped. They got her heart beating again but close to twenty minutes passed in between.

When I saw her in the hospital, she was hooked up to all the machines because she couldn't breathe on her own. Twenty minutes was more than enough for brain damage from lack of oxygen.

Her family decided to let her go because they knew she wouldn't be better again. I hope she rests in peace.

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