What Are Some Causes of Unconsciousness?

Causes of unconsciousness include low blood pressure, dehydration, hyperventilation, low blood sugar and syncope. Abnormal heart rhythm, straining, alcohol poisoning and drug poisoning also cause unconsciousness. Other causes of unconsciousness are severe blood loss, and a blow to the chest or the head, according to Healthline.

Unconsciousness is the inability to respond to stimuli. An unconscious person has a faint pulse and may stop breathing. Additionally, unconscious people lack response to shaking and loud sounds. Fainting is the loss of consciousness for a short period of time. Symptoms that predict unconsciousness include slurred speech, an accelerated heartbeat, lightheadedness and confusion, says Healthline.

To administer first aid to a person experiencing unconsciousness, first confirm that the person is breathing. If the person is not breathing, call 911. If the person is breathing, lay him on his back, raise his legs 12 inches from the ground and loosen his clothing. If the individual doesn't regain consciousness after a minute, call 911. Confirm that the patient's airway is clear, and check for signs of positive circulation such as coughing, breathing and movement. In the absence of positive circulation, perform cardiopulmonary resuscitation, states Healthline.

A coma is a state of prolonged unconsciousness. A patient in a comma is unresponsive to all stimuli including pain. Causes of coma include trauma, swelling of brain tissue, brain bleeding, stroke and oxygen deprivation, according to WebMD.