Necrosis is the death of cells and tissue due to injury or disease. The speed at which it starts depends on the severity of the injury or disease and the amount of time it has been present.
In cases of acute injury, necrosis can start within a few minutes to a few hours. For example, if a person is exposed to extreme cold temperatures, the cells in the affected area will start to die quickly. Similarly, if a person suffers a traumatic injury, such as a crushing or puncture wound, the cells in the affected area will start to die rapidly.
In cases of chronic injury or diseases, necrosis may take days, weeks, or even months to start. For example, in cases of chronic inflammation, necrotic cells may not appear until the inflammation has been present for some time. Similarly, in cases of cancer, necrosis may not be present until the cancer has spread and the tumor has grown significantly.
In general, it is difficult to predict exactly how quickly necrosis will start in any given situation. The best way to reduce the risk of necrosis is to address any underlying causes as soon as possible and to seek medical attention if necessary.