The human body can generally survive without oxygen for about 3 to 6 minutes before permanent brain damage begins to occur. Brain cells start dying after roughly 3 to 5 minutes of oxygen deprivation, with death becoming likely around 4 to 6 minutes without oxygen
. Loss of consciousness can happen within 30 seconds to 3 minutes of oxygen loss, and after about 10 minutes, coma and severe brain damage are almost inevitable, with survival beyond 15 minutes being nearly impossible
. However, survival time can vary depending on factors such as body size, temperature, and metabolic rate. For example, children and women may survive longer due to faster body cooling, which slows metabolism and oxygen use
. Some exceptional cases, such as certain freedivers or people submerged underwater, have survived longer periods without oxygen due to specialized training, pre-breathing pure oxygen, or hypothermia slowing their metabolic rate
. In summary:
- Permanent brain damage begins after about 3-5 minutes without oxygen.
- Death or irreversible damage usually occurs between 4-6 minutes.
- Loss of consciousness can occur within seconds to a few minutes.
- Exceptional cases with cooling or training can extend survival beyond this timeframe.
The critical factor is that the brain needs a continuous supply of oxygen-rich blood, and once this stops, damage accumulates rapidly
