Pneumonitis due to Hypersensitivity: Symptoms, Causes and Treatment

Hypersensitivity pneumonitis is a disease in which the lungs become inflamed when you breathe in certain particles, such as dust, to which you are allergic.

These powders contain fungal spores from moldy hay or bird droppings.

When you inhale the powder for the first time, you will not notice any problems, but some people may develop symptoms after repeated or intense exposure to dust. The tiny air sacs in the lungs become inflamed, their walls fill with white blood cells, and sometimes the sacs fill with fluid.

How severe is hypersensitivity pneumonitis?

There is no cure or effective treatment for hypersensitivity pneumonitis. The good news is that the disease can be completely reversed in its early stages if the dust that causes it is avoided.

The lung scarring or pulmonary fibrosis may occur in the later stages of the disease. This damage is permanent and can happen even after the symptoms have disappeared.

What causes hypersensitivity pneumonitis?

The disease is caused by a natural material inhaled, producing a dust allergy that develops over several months to several years.

The disease occurs most often in people who work in places with high levels of dust that contain mold spores of mold. The most common type of hypersensitivity pneumonitis is the farmer’s lung, which can develop from exposure to moldy hay, straw, and grain.


Hypersensitivity Pneumonitis can also develop from fungi in humidifiers, heating systems, and air conditioners found in homes and offices, especially if they are not well cared for. Exposure to certain bird droppings can also lead to this disease.

Other causes of hypersensitivity pneumonitis are powders of:

  • Sugar cane
  • Barley
  • Maple bark
  • Cork
  • Animal hair
  • Bird feathers and their droppings
  • Coffee beans


The symptoms of an attack are similar to those of the flu and appear about 4-6 hours after the person inhales the powder. They include:

  • Shaking chills
  • Fever
  • Dry cough
  • Difficulty breathing
  • The sensation of tightness in the chest
  • Fatigue

Symptoms can last as little as 12 hours or ten days. You may not have any symptoms between the attacks and feel quite normal.

After repeated exposure to dust, the following symptoms may occur:

  • Chronic cough with much phlegm that contains pus
  • Difficulty breathing
  • Loss of appetite
  • Weightloss

How is hypersensitivity pneumonitis detected?

The doctor will make a detailed and careful history in which you will perform a physical examination and listen to the lungs with a stethoscope. A sign of hypersensitivity pneumonitis is abnormal lung sounds called crackles.

Tests may include:

    • Blood tests
    • Mold tests from your workplace
    • X-ray of the chest
    • Computed tomography of the thorax
    • Pulmonary function tests
    • Lung biopsy


How is hypersensitivity pneumonitis treated?

Avoiding the dust that causes the disease is the most important thing you can do because it is completely reversible in the early stages of the disease.

Most drugs are not very effective in the treatment. Antihistamines and bronchodilators do not work. Steroids can relieve the symptoms of hypersensitivity pneumonitis attacks, but they do not cure the disease. Recovery from attacks can take up to three weeks.

If you have the disease and are a smoker, now is the time to stop smoking. The habit of smoking can worsen the symptoms of the disease. Smokers with hypersensitivity pneumonitis are likely to become uncomfortable with other lung diseases, such as emphysema, chronic bronchitis, or lung cancer.