Chemical Pneumonitis

Overview

Chemical pneumonitis is inflammation of the lung tissue caused by breathing in or aspirating an irritating substance, rather than by an infection. The offending agent damages the delicate lining of the airways and air sacs, triggering inflammation, swelling, and sometimes fluid buildup that interferes with the lungs' ability to take in oxygen.

It can develop suddenly after a single heavy exposure, such as inhaling toxic fumes or aspirating stomach contents or a chemical liquid, or more gradually with repeated low-level exposures. While many mild cases improve with supportive care, severe chemical pneumonitis can be life-threatening and needs urgent medical attention.

Symptoms

Symptoms vary with the substance and the amount inhaled or aspirated. They can come on within minutes to hours.

• Cough, sometimes with frothy or discolored sputum
• Shortness of breath or rapid breathing
• Chest tightness or pain
• Wheezing
• A burning sensation in the nose, throat, or chest
• Fever and a general feeling of being unwell

Severe cases can cause low oxygen levels, bluish lips, and respiratory distress. As with several toxic inhalations, lung injury can sometimes worsen over the hours following exposure.

Causes

Chemical pneumonitis occurs when irritating substances reach the lungs. Common causes include:

• Aspiration: Breathing stomach acid into the lungs, or accidentally inhaling liquids such as certain hydrocarbons (for example, lamp oil, gasoline, or furniture polish), which is especially dangerous in children.
• Toxic fumes and gases: Chlorine, ammonia, nitrogen dioxide, and other irritant gases.
• Smoke and vapors: Fumes from fires, welding, or strong cleaning agents.
• Certain medications and substances reaching the lung: In specific medical circumstances.

The severity depends on the substance, its concentration, and how much entered the lungs.

Risk Factors

• Working with industrial chemicals, solvents, or gases
• Conditions that increase aspiration risk, such as swallowing difficulties or reduced consciousness
• Young children, who may swallow or inhale household liquids
• Pre-existing lung disease
• Exposure to fires, smoke, or strong fumes without protection

Diagnosis

Diagnosis is based on the history of exposure or aspiration combined with examination and tests:

• History and examination: Identifying the exposure and listening to the lungs.
• Oxygen measurement: Checking blood oxygen levels.
• Chest X-ray or CT scan: Showing areas of inflammation or fluid in the lungs.
• Blood tests: To assess overall condition and rule out infection.

Distinguishing chemical pneumonitis from infectious pneumonia is important because the treatments differ.

Treatment

There is no specific cure, so treatment removes the exposure and supports the lungs while inflammation settles.

• Remove the exposure: Get to fresh air and stop further contact with the substance.
• Oxygen and breathing support: Supplemental oxygen, and in severe cases assisted ventilation in hospital.
• Bronchodilators: Inhaled medicines to open narrowed airways.
• Supportive care: Fluids, rest, and close monitoring.
• Other medicines: Corticosteroids may be considered in some cases; antibiotics are added only if infection develops, not routinely.

Importantly, after swallowing a hydrocarbon liquid, vomiting should not be induced because bringing it back up can worsen lung injury.

Prevention

• Store hydrocarbons and household chemicals safely out of reach of children, in labeled containers
• Use ventilation and protective equipment when working with chemicals or fumes
• Never siphon fuel by mouth
• Avoid mixing cleaning products, which can release toxic gases
• Manage swallowing problems and reflux to lower aspiration risk

When to See a Doctor

Call emergency services for severe shortness of breath, choking, bluish lips, or collapse after inhaling or swallowing a chemical, and move the person to fresh air. Seek prompt medical care if you have:

• Persistent cough or worsening breathlessness
• Chest pain or wheezing after exposure
• Fever developing after an inhalation or aspiration event
• Any child who has swallowed lamp oil, fuel, or polish

Because lung injury can worsen over hours, get evaluated even if early symptoms seem mild.

Related Topics

Frequently Asked Questions

References

1. MedlinePlus, U.S. National Library of Medicine. Chemical pneumonitis.
2. Agency for Toxic Substances and Disease Registry (ATSDR). Toxic inhalation injury.
3. American Lung Association. Aspiration pneumonia and pneumonitis.
4. Centers for Disease Control and Prevention (CDC). Toxic gas and fume exposures.