Hyperventilation: Overbreathing. This can cause dizziness, lightheadedness, weakness, shortness of breath, a sense of unsteadiness, muscle spasms in the hands and feet, and tingling around the mouth and fingertips. All of these symptoms are the result of abnormally low levels of carbon dioxide in the blood caused by overbreathing.
Hyperventilation is often due to anxiety or panic. Other less common causes include stimulant use; excessive use of aspirin; pulmonary disease such as asthma, chronic obstructive pulmonary disease (COPD), and pulmonary embolism; infection such as pneumonia or sepsis; heart disease such as congestive heart failure or heart attack; pain; and ketoacidosis when diabetes is out of control.
Reassurance can help relax breathing. Breathing in and out of a paper bag (to increase the level of carbon dioxide in the blood) is no longer recommended (because the level of carbon dioxide can rise too high).
The opposite of hyperventilation is hypoventilation (underventilation).