May also be called: Hypersensitivity Pneumonitis; HP; Extrinsic Allergic Alveolitis; Bird Fancier's Lung; Farmer's Lung; Hot Tub Lung

Pneumonitis (noo-muh-NY-tus) is a general term for inflammation of the lungs.

More to Know

When someone has pneumonitis, it means that tiny air sacs in the lungs called alveoli have become irritated and swollen. Pneumonia (a type of lung infection) is a form of pneumonitis; however, when doctors use the term "pneumonitis," they usually mean an illness that's caused by something a person has inhaled. This can lead to shortness of breath, a dry cough, and other symptoms.

Over time, untreated pneumonitis can lead to lung damage and a condition called pulmonary fibrosis, which can be life-threatening.

Sometimes, the cause of pneumonitis is obvious, but in many cases, it's never found. Radiation treatments and certain drugs can cause pneumonitis; more commonly, people get it from inhaling airborne dust containing certain types of fungus or molds. This is called hypersensitivity pneumonitis. It usually affects people who spend a lot of time around birds and farm workers who are exposed to dust from moldy hay and grain. For this reason, hypersensitivity pneumonitis is sometimes called "bird fancier's lung" or "farmer's lung."

Treatment involves identifying the cause when possible and avoiding it. In chronic cases (those that go on for a long time), doctors may prescribe medicines to reduce inflammation in the lungs or fight infections.

Keep in Mind

In most cases, pneumonitis will clear up on its own if the cause can be identified and successfully avoided. Because long-term inflammation of the alveoli can lead to irreversible lung damage, it's important to talk to a doctor if anyone in your family has pneumonitis symptoms.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.