Wheezing describes a form of difficult, noisy breathing.

Wheezing is often described as a whistling or squeaking noise that occurs when people breathe. It is thought to occur due to narrowed airways. When the airways are narrowed from any cause, the air passing through them may make the noise known as wheezing. Wheezing usually occurs when a person breathes out, or exhales, but may also occur when a person breathes in, or inhales. There are many possible causes.

What are the signs and symptoms of the condition?

If someone complains of wheezing, the healthcare provider will need more information. Questions may be asked related to:

· when the wheezing started

· whether there is any family history of wheezing

· whether the wheezing is constant or comes and goes

· what medications, herbs, or illegal drugs a person takes, if any

· whether or not the person has been exposed to any substances that may irritate the lungs, such as tobacco smoke or industrial chemicals

· what other medical conditions a person has, especially heart and lung conditions

· if anything makes the wheezing better or worse, such as staying inside or being around cats

· any other symptoms, such as fever, weight loss, or cough Sometimes a healthcare provider will detect wheezing during a physical exam when the person doesn't even notice it.

What are the causes and risks of the condition?

Wheezing has many possible causes, including:

· asthma, a condition that causes reversible narrowing of the airways. This usually occurs after exposure to certain triggers, such as pollen, cold air, or exercise.

· chronic obstructive pulmonary disease, or COPD, which includes emphysema and chronic bronchitis. This is usually due to smoking cigarettes.

· heart conditions, such as congestive heart failureand mitral stenosis , a disorder that affects one of the valves of the heart

· cancer or a tumor, particularly primary lung cancer

· heartburn, also called gastroesophageal reflux disease

· allergic reactions, which may be from medications such as penicillin or aspirin, or due to exposure to cat dander, bee stings, a certain food, or some other substance

· infections, such as pneumonia, or an infection usually seen in children called bronchiolitis

· a foreign body somewhere in the windpipes. This commonly occurs in young children who can accidentally inhale small objects they put into their mouths.

· cystic fibrosis, an inherited condition that mainly affects the lungs and digestion

· inflammation of the lung from other conditions, such as a disorder known as sarcoidosis Other causes are also possible. Sometimes no cause can be found.

What can be done to prevent the condition?

Prevention is related to the cause. For instance, avoiding smoking can help prevent most cases due to emphysema or lung cancer. Keeping small objects away from young children can prevent some cases due to a foreign body. Medicines can be used to help prevent wheezing when asthma is the cause. Many cases cannot be prevented.

How is the condition diagnosed?

The first step in figuring out the cause of wheezing is taking a medical history and performing a physical exam. This may be all that is needed to make the diagnosis. In other cases, further tests may be needed. Different tests may be ordered, depending on the suspected cause. For instance, a type of breathing test called pulmonary function testing can help diagnose asthma and COPD. Chest x-rays are commonly used, and can help detect pneumonia, sarcoidosis, and other conditions. Special x-ray tests, such as a chest CT scan, may be needed in certain cases. For instance, a CT scan can help detect lung cancer.