Version July 2025
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What is pneumonitis? —
Pneumonitis, or "hypersensitivity pneumonitis," is a type of lung disease. In this condition, the lungs get irritated because a person breathed in certain chemicals or substances.
Pneumonitis is different from pneumonia. Pneumonia is an infection in the lungs. With pneumonitis, the chemicals do not cause an infection, but they do make the immune system respond. This leads to swelling and inflammation of the tiny air sacs in the lungs. This can also sometimes cause scarring in the lungs.
What can cause pneumonitis? —
Many people breathe in chemicals or substances because of something in their home, job, or hobby.
People are more likely to get pneumonitis if they:
●Work on a farm, are around grain, or process grain
●Work with animals like cattle, poultry, rats, gerbils, or birds
●Are exposed to certain germs from water or ventilation systems, like mold from a hot tub or humidifier that is not cleaned properly
●Work with textiles, plastics, wood, or other types of manufacturing
●Are around certain chemicals
What are the symptoms of pneumonitis? —
The swelling, inflammation, and scarring in the lungs can cause symptoms. Examples include:
●Cough
●Trouble breathing
●Chest tightness
●Feeling tired
●Weight loss
●Fevers or chills
Will I need tests? —
Maybe. Your doctor will do an exam and ask about your symptoms. They will ask about any health problems you have or had in the past, past surgeries, and any medicines you take.
They will also ask about possible exposures to things that can cause pneumonitis. This might include questions about your past or current jobs or hobbies, where you live, and whether you use things like hot tubs or humidifiers.
Your doctor might send you to get tests, such as:
●Chest X-ray or other imaging test – These create pictures of the inside of your body.
●Lab tests
●Breathing tests to see how well your lungs are working
If the doctor needs more information, they might want to do more tests. Examples include:
●Biopsy of lung tissue – The doctor takes a small sample of tissue and looks at it under the microscope.
●Breathing challenge – You breathe in a small sample of what the doctor thinks is causing your symptoms to see how you respond.
How is pneumonitis treated? —
The most important treatment is to avoid the chemical or substance that is causing your symptoms. The doctor might also prescribe a steroid medicine. This can help reduce the inflammation and swelling in your lungs.
For more serious cases, you might need:
●Oxygen – This can help you breathe more comfortably.
●Other anti-inflammatory medicines – If you take these, you might be able to take steroids for a shorter time or stop taking them.
●Medicines to prevent scarring in the lungs
●Pulmonary rehabilitation ("rehab") – This is a program that includes exercise, education, and healthy lifestyle changes to help you feel better and cope with your condition.
People with very serious cases of pneumonitis (for example, their lungs have a lot of scarring) might need a lung transplant.
What can I do on my own to feel better?
●Try to avoid whatever chemical or substance is causing your symptoms, if possible.
●Quit smoking, if you smoke. Smoking can make your symptoms worse. If you are having trouble quitting, your doctor or nurse can help.
Can pneumonitis be prevented? —
You can lower your risk of getting pneumonitis by avoiding chemicals and substances that cause inflammation in the lungs.
You can also:
●If you have to be around chemicals or irritants in the air, wear a special mask with a filter.
●Use an air filter in your home to remove allergens and other irritating things from the air.
●Clean and sanitize heating and air conditioning systems, as well as things like hot tubs and humidifiers.
When should I call the doctor? —
Call for advice if:
●You have a fever of 100.4°F (38°C) or higher, or chills.
●You are having so much trouble breathing you can only say 1 or 2 words at a time.
●You need to sit upright to breathe, or you cannot lie down.
●You have trouble breathing when talking or sitting still.
●Your shortness of breath has not gotten better after a few days.
●You cough up blood.
●Your symptoms are not improving after 3 to 4 weeks of treatment.
Patient education: Breathing tests (The Basics)
Patient education: Oxygen therapy at home (The Basics)
Patient education: Pulmonary rehabilitation (The Basics)
Patient education: Quitting smoking for adults (The Basics)
Patient education: Quitting smoking for teens (The Basics)
Patient education: Pneumonia in adults (The Basics)
Patient education: Pneumonia in children (The Basics)
Patient education: Quitting smoking (Beyond the Basics)
Patient education: Pneumonia in adults (Beyond the Basics)
