Asphyxia is a condition of severe lack of oxygen supplied to the body. In the absence of remedial action it will very rapidly lead to unconsciousness and death. Asphyxia is the same as suffocation and anoxia. Asphyxiation is the act of causing asphyxia, usually by suffocation.

Asphyxia in humans is a medical emergency.

Causes of asphyxia can include:

• Crushing or constriction of the chest or abdomen
• Choking
• Drowning
• Strangulation, or external constriction of the neck or throat, e.g. by a human or a snake)
• Reduction of the airways due to anaphylaxis or asthma
• Inhalation of vomit
• Positional asphyxia
• Autoerotic asphyxiation
• a seizure which stops breathing activity

Prolonged asphyxia can result in brain damage even when it does not cause death.