Hypersensitivity pneumonitis

By Medically reviewed by hellodoktor


What is hypersensitivity pneumonitis?

Hypersensitivity pneumonitis is a condition of the lungs in which your lungs become inflamed as an allergic reaction to inhaled dust, fungus, molds or chemicals.

Hypersensitivity pneumonitis is caused by an allergy to certain dust (allergens) that you breathe in. Commonly, these allergens are naturally occurring (organic). These allergens may be present at home, work or in the environment. Commonly, these dusts contain fungus spores from moldy hay or bird droppings.

Hypersensitivity pneumonitis can become a serious condition for some individuals whose lungs develop scarring. Lung scarring (also called pulmonary fibrosis) may occur in the later stages of the disease. The lung scarring is permanent. Unfortunately, there is no cure or effective treatment for chronic (or long-standing) hypersensitivity pneumonitis.

How common is hypersensitivity pneumonitis?

Hypersensitivity pneumonitis is estimated to affect anywhere from 0.5–19.0% of exposed farmer. Bird fancier’s lung is the most form of hypersensitivity pneumonitis worldwide given a growing poultry husbandry industry

Please discuss with your doctor for further information.


What are the symptoms of hypersensitivity pneumonitis?

The signs and symptoms of hypersensitivity pneumonitis are likely similar to usual flu when the acute attack occurs. It appears about 4 to 6 hours after you inhale the dust. The signs and symptoms seen are:

  • Dry cough
  • Shortness of breath
  • Chest tightness
  • Fever
  • Chills
  • Tiredness

The initial symptoms may last for as little as 12 hours but may continue for several days in some individuals. If you have repeated exposure to the dust, the following symptoms may be seen.

  • Shortness of breath, especially with activity
  • Dry cough
  • Unintentional weight loss

When should I see my doctor?

If you have any signs or symptoms listed above or have any questions, please consulting with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.


What causes hypersensitivity pneumonitis?

There are more than 300 known substances which, when inhaled as a fine dust, have been known to cause hypersensitivity pneumonitis. Some commonly seen problems are given specific names related to the source of the dust, including:

Farmer’s lung

It is seen in farmers and cattle workers, this condition is caused by breathing mold that grows on hay, straw and grain.

Bird fancier’s lung(also called pigeon breeder’s disease)

It is caused by breathing particles from feathers or droppings of many species of birds.

Humidifier lung

It can develop by breathing in fungus growing in humidifiers, air conditioners and heating systems, particularly if they are not well maintained.

Hot tub lung

It may develop by breathing in bacteria that may be found in the water vapor coming from indoor hot tubs.

Risk factors

What increases my risk for hypersensitivity pneumonitis?

There are many risk factors for hypersensitivity pneumonitis such as:

  • You work in certain occupations, you may be at an increased risk of developing hypersensitivity pneumonitis. This includes farmers, vegetable or dairy cattle workers, bird and poultry handlers, veterinary workers and animal handlers, grain and flour processing and loaders, lumber milling, wood stripping and paper and wallboard manufacturers.
  • Inhaling certain chemicals produced in plastic manufacturing, painting, and the electronics industry.

Most individuals who work in such occupations do not develop hypersensitivity pneumonitis. It appears that certain genetic factors determine if you are going to develop hypersensitivity pneumonitis or not. Unfortunately, at this time, there is not much information about the genes that can predispose a person to develop hypersensitivity pneumonitis.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is hypersensitivity pneumonitis diagnosed?

If your doctor suspects you may experience hypersensitivity pneumonitis, he or she may perform a physical examination. And then some recommended tests may include:

Chest x-ray and CT scan

It may be able to show early stages of the disease and if there is any scarring.

Lung function tests

It shows how well you breathe to see if your lungs are working correctly.

Blood tests

It is done to find out if you have developed antibodies against the dust (allergen). These blood tests can help show if you have been exposed to a certain dust.


It is performed when a bronchoscope (small flexible tube about the size of a pencil with a video camera attached at its end) is passed either through your nose or mouth. This tool can be used to collect specimens from your lung for further testing.

Video-assisted thoracic surgery (VATS) or open lung biopsy

This procedure is performed by a cardiothoracic surgeon under general anesthesia. It is another way to get lung tissue for further testing.

How is hypersensitivity pneumonitis treated?

The single most important thing that you can do is avoid the dust that causes the disease. If you do so, your lungs can return to normal function, as the disease is completely reversible in the early stages. Completely avoiding the dust is sometimes not possible, unless you remove yourself from the dust-causing environment.

In patients who have severe cases, treatment may include prescription steroids, such as prednisone. You may be required to take this medication for up 3 months and sometimes longer.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Hypersensitivity pneumonitis?

The following lifestyles and home remedies might help you cope with hypersensitivity pneumonitis:

  • Allergy-causing bacteria and fungus can thrive in stagnant, or still, water. Be sure to remove any standing water inside and outside your home.
  • Take efforts to keep the humidity in your home and work below 60%.
  • Immediately repair any water damage inside your home or work. This includes removing water-damaged carpeting, furnishings and drywall.
  • Properly maintain your heating, ventilation and air conditioning systems.
  • Make sure that the water in heating, air conditioning and ventilation systems is not recirculated.
  • Properly dry and store farm products if you work with them.

If you have any questions, please consult with your doctor to better understand the best solution for you

Hello Health Group does not provide medical advice, diagnosis or treatment.

Review Date: August 16, 2017 | Last Modified: September 12, 2019