What is acute respiratory distress syndrome (ARDS)?

Acute respiratory distress syndrome, or ARDS, is an inflammatory lung injury that happens when fluids build up in small air sacs (called alveoli) in the lungs. ARDS prevents the lungs from filling up with air and causes dangerously low oxygen levels in the blood (hypoxemia).

This condition prevents other organs such as brain, heart, kidneys and stomach from getting the oxygen they need to function. ARDS is dangerous and can lead to a number of serious and life-threatening problems.

ARDS typically happens in hospital settings while the patient is being treated for infection or trauma. If you’re not hospitalized and experience symptoms of ARDS, get medical attention immediately.

What causes acute respiratory distress syndrome (ARDS)?

ARDS is caused when fluids leak from small lung vessels into lung air sacs (alveoli). When the protective membrane between blood vessels and air sacs is compromised, levels of oxygen in the blood decrease.

Causes of ARDS include:

  • Sepsis: The most common cause of ARDS, a serious infection in the lungs (pneumonia) or other organs with widespread inflammation.
  • Aspiration pneumonia: Aspiration of stomach contents into the lungs may cause severe lung damage and ARDS.
  • The coronavirus (COVID-19): The infection COVID-19 may develop into severe ARDS.
  • Pancreatitis (severe inflammation in the pancreas), and massive blood transfusion.
  • Major trauma and burns: Accidents and falls may directly damage the lungs or other organs in the body that trigger severe inflammation injury in the lungs.
  • Inhalational injury: Breathing and exposure to high concentrations of chemical fumes or smoke.
  • Drug overdose: An overdose on drugs like cocaine and opioids.

What are the symptoms of acute respiratory distress syndrome (ARDS)?

Symptoms of ARDS depend on the cause and severity of the case, as well as pre-existing lung or heart conditions. Symptoms include:

  • Severe shortness of breath or breathlessness.
  • Rapid and labored breathing.
  • Extreme tiredness and muscle fatigue.
  • Confusion.
  • Rapid heart rate.
  • Bluish color of fingernails and lips due to low oxygen level in the blood.
  • Cough and chest pain.

If ARDS is caused by severe infection (sepsis), symptoms of sepsis may also be present (fever, low blood pressure).

How quickly can acute respiratory distress syndrome (ARDS) develop?

ARDS tends to develop within a few hours to a few days of the event that caused it. ARDS can worsen rapidly.

Last reviewed by a Cleveland Clinic medical professional on 06/20/2020.


  • American Lung Association. Learn about ARDS. Accessed 6/29/2020.
  • National Heart, Blood, and Lung Institute. Acute Respiratory Distress Syndrome. Accessed 6/29/2020.
  • Udobi KF, Childs E, Touijer K. Acute respiratory distress syndrome. Am Fam Physician. 2003;67(2):315-322. Accessed 6/29/2020.
  • Santacruz JF, Diaz Guzman Zavala E, Arroliga AC. Update in ARDS management: recent randomized controlled trials that changed our practice. Cleve Clin J Med 2006;73:217-236.

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy