Hyperventilation means breathing too fast and/or too deeply. This causes the lungs to remove carbon dioxide from the blood and this affects the amount of acid in the blood and causes a variety of symptoms, most commonly tingling in the fingers and toes, some headache and breathlessness and sometimes even chest pain. Often it comes on fairly acutely and then subsides. The condition is not at all serious even though the symptoms can be quite distressing. It may be caused by abnormal control of the breathing, and usually resolves spontaneously over time. It can sometimes occur in the context of other lung diseases.