Hyperventilation is rapid or deep breathing, usually caused by anxiety or panic. This overbreathing, as it is sometimes called, may actually leave you feeling breathless.

When you breathe, you inhale oxygen and exhale carbon dioxide. Excessive breathing may lead to low levels of carbon dioxide in your blood, which causes many of the symptoms that you may feel if you hyperventilate.

Feeling very anxious or having a panic attack are the usual reasons that you may hyperventilate. However, rapid breathing may be a symptom of an underlying disease, such as a heart or lung disorder, bleeding, or an infection. (See rapid shallow breathing.)

Your doctor will determine the cause of your hyperventilation. Rapid breathing may be considered a medical emergency -- unless you have experienced this before and have been reassured by your doctor that your hyperventilation can be self treated. (See below.).

Often, panic and hyperventilation become a vicious cycle -- panic leads to rapid breathing while breathing rapidly can make you feel panicked.

If you frequently overbreathe (sometimes referred to as hyperventilation syndrome), this may be triggered by ongoing emotions of stress, anxiety, depression, or anger. However, hyperventilation from panic is generally related to a specific fear or phobia, such as a fear of heights, dying, or closed-in spaces (claustrophobia).

If you have hyperventilation syndrome -- that is, if you regularly hyperventilate -- you might not be aware of it. But you will be aware of having many of the associated symptoms, including dizziness or lightheadedness, shortness of breath, belching, bloating, dry mouth, weakness, confusion, sleep disturbances, numbness and tingling in your arms or around your mouth, muscle spasms in hands and feet, chest pain, and palpitations.

• anxiety and nervousness
• stress
• panic attack
• situations where there is a psychological advantage in having a sudden, dramatic illness (for example, somatization disorder)
• stimulant use
• lung disease such as asthma, chronic obstructive pulmonary disease (COPD), or pulmonary embolism (blood clot in the lung)
• infection such as pneumonia or sepsis
• cardiac disease such as congestive heart failure or heart attack
• severe pain
• bleeding
• drugs (such as an aspirin overdose)
• pregnancy
• ketoacidosis and similar medical conditions

Assuming that a more serious, underlying cause of hyperventilation has been eliminated and your doctor has explained that you hyperventilate from anxiety, stress, or panic, there are steps you can take at home. You, your friends, and family can learn techniques to stop you from hyperventilating when it happens and to prevent future attacks.

If you start hyperventilating, the goal is to raise the carbon dioxide level in your blood, which will put an end to most of your symptoms. There are several ways to do this:

1. Reassurance from a friend or family member can help relax your breathing. Words like "you are doing fine," "you are not having a heart attack," and "you are not going to die" are very helpful. It is extremely important that the person helping you remain calm and deliver these messages with a soft, relaxed tone.
2. To increase your carbon dioxide, you need to take in less oxygen. To accomplish this, you can breathe through pursed lips (as if you are blowing out a candle) or you can cover your mouth and one nostril, breathing through the other nostril.

Over the long term, there are several important steps to follow to try to eliminate your tendency to overbreathe:

1. If anxiety or panic has been diagnosed, see a psychologist or psychiatrist to help you understand and treat your condition.
2. Learn breathing exercises that help you relax and breathe from your diaphragm and abdomen, rather than your chest wall.
3. Practice relaxation techniques regularly, such as progressive muscle relaxation or meditation.
4. Exercise regularly.

If these methods alone are not preventing your overbreathing, your doctor may recommend a beta blocker medication.

• You are experiencing rapid breathing for the first time. (This is a medical emergency and you should be taken to the emergency room right away.)
• You are in pain, have a fever, or notice any bleeding.
• Hyperventilation persists or worsens despite home treatment, or if it is accompanied by other symptoms.

Your doctor will perform a careful physical examination.

To obtain your medical history, your doctor will ask questions about your symptoms like:

• Do you feel short of breath?
• What other symptoms do you have when you are breathing rapidly? Do these symptoms start at any other time (for example, when you are walking or exercising)?
• Do you have any underlying medical conditions like high blood pressure, diabetes, or high cholesterol?
• What medications do you take?
• What is happening in your life in general? Has it been a particularly stressful time?
• Do you feel anxious or stressed, especially before you start breathing rapidly?
• Are you in pain? What does the pain feel like? How intense is the pain? Where is it located?
• What other symptoms do you have (for example, have you had any bleeding? Are you dizzy?)

The doctor will assess how rapidly you are breathing at the time of the visit. If you are not breathing quickly, the physician may try to induce hyperventilation by instructing you to breathe a certain way.

While you hyperventilate, the doctor will ask how you feel and watch how you breathe -- including what muscles you are using in your chest wall and surrounding areas.

Tests that may be performed include:

• ECG
• X-rays of the chest
• Blood tests for the oxygen and carbon dioxide levels in your blood
• Chest CT scan
• Ventilation/perfusion scan of your lungs