Skip navigation
MedlinePlus Trusted Health Information for You U.S. National Library of MedicineNational Institutes of Health
Contact Us FAQs Site Map About MedlinePlus
español Home Health Topics Drugs & Supplements Medical Encyclopedia Dictionary News Directories Other Resources

 

Medical Encyclopedia

Other encyclopedia topics:  A-Ag  Ah-Ap  Aq-Az  B-Bk  Bl-Bz  C-Cg  Ch-Co  Cp-Cz  D-Di  Dj-Dz  E-Ep  Eq-Ez  F  G  H-Hf  Hg-Hz  I-In  Io-Iz  J  K  L-Ln  Lo-Lz  M-Mf  Mg-Mz  N  O  P-Pl  Pm-Pz  Q  R  S-Sh  Si-Sp  Sq-Sz  T-Tn  To-Tz  U  V  W  X  Y  Z  0-9 

Hypersensitivity pneumonitis

Printer-friendly versionEmail this page to a friend
Contents of this page:

Illustrations

Bronchoscopy
Bronchoscopy
Respiratory system
Respiratory system

Alternative Names    Return to top

Extrinsic allergic alveolitis; Farmer's lung; Mushroom picker's disease; Humidifier or air-conditioner lung; Bird breeder's lung

Definition    Return to top

Hypersensitivity pneumonitis is inflammation of the lungs due to breathing in a foreign substance, usually certain types of dust, fungus, or molds.

Causes    Return to top

Hypersensitivity pneumonitis usually occurs in those who work in places where there are high levels of organic dusts, fungus, or molds. For example, farmer's lung is the most common type of hypersensitivity pneumonitis. Repeated or intense exposure to dust from moldy hay, straw, and grain can lead to lung inflammation and acute lung disease. Over time, this acute condition may turn into long-lasting (chronic) lung disease.

The condition may also result from fungus present in humidifiers, heating systems, and air conditioners found in homes and offices. Exposure to certain bird droppings (for example, among bird owners) can also lead to hypersensitivity pneumonitis.

Symptoms    Return to top

Symptoms of acute hypersensitivity pneumonitis may occur 4 - 6 hours after you have left the area where the foreign substance is found. These symptoms may include:

Symptoms of chronic hypersensitivity pneumonitis may include:

Exams and Tests    Return to top

Your doctor may hear abnormal lung sounds called crackles (rales) when listening to your chest with a stethoscope.

Lung changes due to chronic hypersensitivity pneumonitis may be seen on chest x-ray. Other tests may include:

Treatment    Return to top

First, the foreign substance must be identified. Treatment involves avoiding this substance in the future. Some people may need to change jobs if they can not avoid the substance at work.

If you have a chronic form of this disease, your doctor will give you glucocorticoids (power anti-inflammatory medicines).

Outlook (Prognosis)    Return to top

Most symptoms go away when you avoid or limit your exposure to the material that caused the problem.

Possible Complications    Return to top

The chronic form of this disease may lead to pulmonary fibrosis (a scarring of the lung tissue that is often not reversible).

When to Contact a Medical Professional    Return to top

Call your health care provider if symptoms of hypersensitivity pneumonitis develop.

Prevention    Return to top

The chronic form can be prevented by avoiding the material that causes the lung inflammation.

References    Return to top

Hoppin JA, Umbach DM, Kullman GJ, et al. Pesticides and other Agricultural Factors Associated with Self-reported Farmer's lung among Farm Residents in the Agricultural Health Study. Occup Environ Med. 2006 Dec 20;[Epub ahead of print].

Lacasse Y, Cormier Y. Hypersensitivity pneumonitis. Orphanet J Rare Dis. 2006 Jul 3;1:25.

Update Date: 3/16/2007

Updated by: David A. Kaufman, M.D., Assistant Professor, Division of Pulmonary, Critical Care & Sleep Medicine, Mount Sinai School of Medicine, New York, NY. Review provided by VeriMed Healthcare Network.

A.D.A.M. Logo

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2008, A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.