Key Points About Pneumonitis

  • Pneumonitis is a lung condition that occurs when an irritant causes inflammation in the lungs.
  • Pneumonitis is caused by breathing in irritants such as mold, bacteria, fungi, or chemicals found in animal fur, bird droppings, hot tubs, contaminated foods, or humidifiers.
  • You are at higher risk for developing pneumonitis if you have a career where you are exposed to irritants regularly.
  • While there is not a specific cure for pneumonitis, you can relieve your symptoms with treatments.
  • Your primary care or pulmonologist can diagnose pneumonitis in a clinic exam, using your symptoms, medical history, exposure to irritants, and a series of diagnostic testing such as blood tests, imaging tests, pulmonary function tests, bronchoscopy, and lung biopsy.
  • Treatments may include avoidance, medical management, oxygen therapy, bronchodilators, and as a last resort - lung transplant.
  • Seek treatment immediately if you are having trouble breathing.


Pneumonitis is a type of allergic reaction characterized by inflammation in your lungs. It can occur when an irritant such as mold irritates the lungs causing swelling and inflammation. While anyone can develop pneumonitis, it is more common in people who are especially sensitive to these substances.

Pneumonitis can be treated. If not treated early, it can cause severe lung scarring and damage.

Pneumonitis causes

You may develop pneumonitis if you breathe in substances that irritate the lungs' alveoli (small air sacs). When you are exposed to an irritating substance, your body will react by producing inflammation. This makes it harder for oxygen to pass through the alveoli into the bloodstream.

Substances such as mold, bacteria, fungi, or chemicals can trigger pneumonitis. These substances can often be found in animal fur, bird droppings or feathers, hot tubs, humidifiers, or contaminated foods.

Antibiotics, chemotherapy medications for arrhythmia medications may also cause pneumonitis.

Pneumonitis risk factors

There are a variety of factors that can increase your risk of developing pneumonitis.

Risk factors include:

  • Occupation - professions where you are regularly exposed to irritants may increase your risk of developing pneumonitis, they include:
    • Farmers
    • Poultry or bird handlers
    • Animal breeders
    • Lumber millers
    • Grain processors
    • Wine producers
    • Electronic or plastic manufacturers
  • Genetic predisposition - people with a genetic predisposition to pneumonitis are more likely to develop the condition.
  • Age - while you can develop pneumonitis at any age, it is most common in people between the ages of 50 and 55.
  • Exposure to molds - if you have been exposed to mold in hot tubs, humidifiers, air conditioners, or heating systems, you are at a higher risk of developing pneumonitis.
  • Cancer treatments - patients who are taking specific chemo drugs or get radiation therapy are at higher risk of developing pneumonitis.

Pneumonitis symptoms

Symptoms of acute pneumonitis generally appear four to six hours after breathing in an irritating substance. Initially, you may experience symptoms such as:

  • Fever
  • Chills
  • Muscle or joint pain
  • Headaches

Symptoms should go away in a few days if you are not exposed to the irritant again. People who are continually exposed may develop chronic pneumonitis. Symptoms of chronic pneumonitis include:

  • Dry cough
  • Fatigue
  • Tightening in your chest
  • Loss of appetite
  • Unintentional weight loss

Pneumonitis complications

If left untreated, pneumonitis can cause severe, irreversible lung damage.

Chronic inflammation can lead to pulmonary fibrosis, which, in severe cases, can cause heart failure, respiratory failure, and death.

Pneumonitis diagnosis

If you suspect you have pneumonitis, schedule an appointment with your primary care or pulmonology doctor. A pulmonologist is a type of physician who specializes in lung diseases.

During the clinic visit, your doctor will take a full medical history, ask you what substances you could have been exposed to, and perform a physical exam.

Your doctor will listen to your lungs to determine if you have any abnormal sounds in your lungs.

If your doctor suspects you may have pneumonitis, he or she may order testing such as:

  • Oximetry measures the amount of oxygen in your blood.
  • Blood tests - your doctor may order blood tests to determine if you have any antibodies in your blood against irritants such as dust or mold.
  • X-ray - a chest X-ray can reveal lung scarring or other damage.
  • CT scan - a CT scan provides higher resolution and higher quality images than an X-ray to reveal lung damage.
  • Spirometry tests measure your airflow while you breathe in and out.
  • A bronchoscopy may be performed to remove lung cells for testing.
  • Lung biopsy - during a lung biopsy, your doctor will remove a sample of tissue from the lung to evaluate for damage.

Pneumonitis treatment

The most effective treatment for pneumonitis is avoidance. If you can avoid substances that trigger your symptoms, your symptoms can be relieved. If you have a job where you work around the irritating material, you may need to consider changing careers.

While pneumonitis cannot be cured, treatments can help relieve your symptoms.

Treatments include:

  • Corticosteroids, such as prednisone, can reduce your inflammation.
  • Oxygen therapy - oxygen therapy can help you breathe easier.
  • A bronchodilator can help you breathe easier by relaxing the airways.
  • Lung transplant - lung transplant is the last resort option for patients with severely damaged lungs who cannot breathe well after other treatment options.

When to Seek Care

Anytime you have trouble breathing, contact your doctor right away. If you are having severe shortness of breath, seek immediate care. If you are having noticeable shortness of breath, schedule an appointment with your doctor.

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