Hyperventilation is breathing that is deeper and more rapid than normal. It causes a decrease in the amount of a gas in the blood. (This gas is called carbon dioxide, or CO2.) The decrease may make you feel lightheaded. You may have a rapid heartbeat and be short of breath.

Hyperventilation is a condition with multiple etiologies in which the respiratory rate is abnormally increased, such that there are significant changes in blood gases (O2 and CO2) and acid-base chemistry, causing many signs and symptoms.