Acute Respiratory Distress Syndrome
Acute Respiratory Distress Syndrome

Acute Respiratory Distress Syndrome Causes and Risk Factors

What causes acute respiratory distress syndrome?

Damage to the lung’s air sacs (called alveoli) causes ARDS. Fluid from tiny blood vessels leaks through the damaged walls of the air sacs and collects, limiting the lungs’ normal exchange of oxygen and carbon dioxide. The damage also causes inflammation that leads to the breakdown of surfactant — a liquid that helps keep your air sacs open.

The air sacs may become damaged as a result of an illness, such as a lung infection, or breathing in smoke. Other illnesses or injuries may trigger inflammation that damages the air sacs. To understand ARDS, you may also want to read about how the lungs work.

Speak with your doctor if you have any symptoms of ARDS. Your doctor will diagnose ARDS based on your medical history, a physical exam, and test results.

Illustration of ARDS
The image on the left shows the location of the lungs, trachea, and bronchi within the body. The middle image shows the normal gas exchange of oxygen and carbon dioxide through the air sacs. The image on the right shows the fluid buildup in the air sacs of someone who has ARDS. The fluid buildup prevents gas exchange. Medical Illustration Copyright © 2022 Nucleus Medical Media, All rights reserved.

What raises the risk of ARDS?

You may have an increased risk of ARDS because of an infection, environmental exposures, lifestyle habits, or another medical condition. Risk factors can vary depending on your age, overall health, where you live, and the healthcare setting in which you receive care.

When diagnosing ARDS, doctors will use information about causes and risk factors to tailor a treatment that improves oxygen levels and treats underlying causes.


Infections are the most common risk factors for ARDS. The most common are flu or other viruses , such as respiratory syncytial virus and SARS-CoV-2, the virus responsible for COVID-19. Watch this video to learn more about how COVID-19 affects the lungs.

Other infections may include:

  • Pneumonia
  • sepsis , a condition in which bacteria infect the bloodstream
  • Uterine infection in the mother, affecting a newborn’s lungs


Being exposed to air pollution for weeks or months can make you more vulnerable to ARDS.

Lifestyle habits

Habits that harm the health of your lungs increase your risk of ARDS. These include:

  • Heavy alcohol use
  • Overdose of illegal drugs
  • Smoking

Family history and genetics

The Genes you inherit may put you at an increased risk for ARDS. These genes play a role in how the lungs respond to damage.

Other medical conditions or procedures

Other medical conditions, injuries, or medical procedures can raise your risk for ARDS. These may include:

  • Inhaling vomit, smoke, chemical fumes, or water during a near drowning
  • Injury: An injury from a blow, burn, or broken bone can lead to ARDS. A broken bone, for example, can lead to a fat embolism, a clot of fat that blocks an arteries .
  • Lung or heart surgery or being placed on a heart-lung bypass machine or ventilator
  • Pancreatitis, a condition in which the pancreas (a gland that releases enzymes and hormone ) becomes infected
  • Reaction to medicines, such as those used to treat cancer or arrhythmia

Newborn lung conditions can raise your baby’s risk of neonatal ARDS. These conditions include pneumonia and a condition where the unborn baby passes stool while still in the womb and then inhales the stool into his or her lungs. Your baby is also at higher risk for ARDS if they did not get enough oxygen during delivery.

Can ARDS be prevented?

You can help lower your risk of ARDS with the following steps:

  • Get routine vaccines to prevent the flu, COVID-19, and other infections.
  • Avoid tobacco smoke.
  • Limit the amount of alcohol you drink. (The recommended amount is no more than 2 drinks per day for men and 1 drink per day for women.)
  • Limit exposure to pollution as much as possible.

If you have a condition that puts you at risk of ARDS, getting early treatment may help prevent the syndrome. Your doctor and healthcare team may try to prevent ARDS by treating infection or shock, managing your fluid levels carefully, and managing the settings of your ventilator.

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