ARDS (Acute Respiratory Distress Syndrome)

ARDS (acute respiratory syndrome) definition and facts*

*ARDS facts Medically Edited by: Melissa Conrad Stöppler, MD

  • ARDS, or acute respiratory distress syndrome, is a lung condition that leads to low oxygen levels in the blood. ARDS can be life-threatening. This is because your body's organs, such as the kidneys and brain, need oxygen-rich blood to work properly.
  • Most people who develop ARDS are in the hospital for other serious health problems. Rarely, people who aren't hospitalized have health problems that lead to ARDS, such as severe pneumonia. If you have trouble breathing, call your doctor right away. If you have severe shortness of breath, call an ambulance or emergency medical services like 911 immediately.
  • Causes of ARDS include infections, injuries, or other conditions that cause the lung's tiny blood vessels to leak more fluid than normal into the lungs' air sacs. This prevents the lungs from filling with air and moving enough oxygen into the bloodstream.
  • Some common conditions and factors that cause ARDS are sepsis, pneumonia, severe bleeding caused by an injury, an injury to the chest or head, breathing in harmful fumes or smoke, and inhaling vomited stomach contents from the mouth.
  • Risk factors for ARDS include any condition or illness that can directly or indirectly injure the lungs.
  • The first signs and symptoms of ARDS are feeling like you can't get enough air into your lungs, rapid breathing, and low oxygen levels in the blood. Other signs and symptoms depend on the cause of the condition. They may occur before ARDS develops.
  • Your doctor will diagnose ARDS based on your medical history, a physical exam, and the results from tests.
  • Treatment of ARDS involves oxygen therapy, fluids, and medicines. Treatments are done in a hospital's intensive care unit. Patients who have ARDS may develop other medical problems while in the hospital. The most common problems are infections, pneumothorax (collapsed lung), lung scarring, and blood clots. The survival rate for people with ARDS is dependent upon the underlying disease as well as the overall health status of the patient.
  • Some people fully recover from ARDS. Others continue to have health problems. These problems may include shortness of breath, tiredness and muscle weakness, depression, and problems with memory and thinking clearly.
  • You can take steps to recover from ARDS and improve your quality of life. Ask your family and friends to help with everyday activities. Don't smoke and avoid secondhand smoke and other lung irritants, such as harmful fumes. Go to pulmonary rehabilitation if your doctor recommends it. Join a support group for ARDS. Seek help from your health care team if you feel depressed.
  • ARDS treatment has improved in recent years. As a result, the survival rate for ARDS is improving. Researchers are studying new treatments for the condition.

What is ARDS?

Acute respiratory distress syndrome (ARDS) is dangerous lung damage
ARDS is caused due to fluid leakage from the small lung vessels into the lung air sacs (alveoli). It causes difficulty in breathing and severe falls in oxygen in the body.

Acute respiratory distress syndrome (ARDS) is a serious lung condition that causes low blood oxygen. People who develop ARDS are usually ill due to another disease or a major injury. In ARDS, fluid builds up inside the tiny air sacs of the lungs, and surfactant breaks down. A surfactant is a foamy substance that keeps the lungs fully expanded so that a person can breathe. These changes prevent the lungs from filling properly with air and moving enough oxygen into the bloodstream and throughout the body. The lung tissue may scar and become stiff.

ARDS may develop over a few days, or it can get worse very quickly. The first symptom of ARDS is usually shortness of breath. Other signs and symptoms of ARDS are low blood oxygen, rapid breathing, clicking, bubbling, or rattling sounds in the lungs when breathing.

ARDS can develop at any age. To diagnose ARDS, your doctor or your child’s doctor will do a physical exam, review the patient’s medical history, measure blood oxygen levels, and order a chest X-ray. Supplying oxygen is the main treatment for ARDS. Other treatments help make you more comfortable or aim to eliminate the cause of ARDS. Treatments for ARDS may help prevent serious or life-threatening complications, including organ damage or organ failure.

ARDS symptoms and signs

Signs and symptoms that you are developing or are at risk for ARDS may include:

If you have trouble breathing, call your doctor right away. If you have severe shortness of breath, call 9-1-1.


COPD (chronic obstructive pulmonary disease) is the same as adult-onset asthma. See Answer

What causes ARDS?

Many conditions or factors can directly or indirectly injure the lungs and lead to ARDS. Some common ones are:

  • Sepsis. This is a condition in which bacteria infect the bloodstream.
  • Pneumonia. This is an infection in the lungs.
  • Severe bleeding caused by an injury to the body.
  • An injury to the chest or head, like a severe blow.
  • Breathing in harmful fumes or smoke.
  • Inhaling vomited stomach contents from the mouth.

It's not clear why some very sick or seriously injured people develop ARDS and others don't. Researchers are trying to find out why ARDS develops and how to prevent it.

Risk factors

People at risk for ARDS have a condition or illness that can directly or indirectly injure their lungs. You may have an increased risk of ARDS because of infection, environmental exposures, lifestyle habits, genetics, other medical conditions or procedures, race, or sex. Risk factors can vary depending on your age, overall health, where you live, and the healthcare setting in which you receive care.


Infections are the most common risk factors for ARDS. These may include:

  • Flu or other viruses, such as respiratory syncytial virus and SARS-CoV-2, are the virus responsible for COVID-19. Watch this video external link to learn more about how COVID-19 affects the lungs. Additionally, we offer information and resources on how we are working hard to support necessary COVID-19 research. 
  • Pneumonia
  • Sepsis, is 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:

  • Blood transfusions
  • Fat embolism, in which a clot of fat blocks an artery. A physical injury, such as a broken bone, can lead to a fat embolism.
  • Hemorrhagic shock
  • Inhaling vomit, smoke, chemical fumes, or water during a near-drowning
  • Injuries, such as from a blow or burns
  • Lung injury from being on a ventilator
  • Lung or heart surgery, or being placed on a heart-lung bypass machine
  • Newborn lung conditions can raise the risk of your baby having neonatal ARDS. These include pneumonia and a condition where the unborn baby passes stool while still in the womb, and the stool is then inhaled into his or her lungs. Your baby is also at higher risk if he or she did not get enough oxygen during delivery.
  • Pancreatitis is a condition in which the pancreas becomes infected. The pancreas is a gland that releases enzymes and hormones.
  • Pulmonary vasculitis
  • Reaction to medicine, such as those used to treat cancer or arrhythmia

Race or ethnicity

The risk of developing ARDS is higher among nonwhite groups.


Among children, boys are at a higher risk of ARDS than girls are.

Learn more about how ARDS in newborns is different from respiratory distress syndrome, a similar breathing condition that also affects newborns.

How do doctors diagnose the condition?

Your doctor will diagnose ARDS based on your medical history, physical exam, and test results. ARDS can be difficult to diagnose and is often mistaken for another condition, so it is important to know your symptoms.

Medical history

To help diagnose ARDS, your doctor may ask you about any medical conditions or recent events that could be considered risk factors. For example, traveling could be a risk factor because of potential exposure to infections that are more common in certain geographic areas. Your doctor may also ask about your symptoms and whether you have a heart problem, such as heart failure, or another condition that can cause signs and symptoms similar to those for ARDS.

Physical exam

Your doctor will examine you for signs of ARDS. This exam may include:

  • Listening to your lungs through a stethoscope for abnormal breathing sounds, such as crackling
  • Listening to your heart for a fast heart rate
  • Checking for signs that you are having difficulty breathing, such as using muscles in your chest to help you breath
  • Examining your skin or lips for a bluish tone can signal a low blood oxygen level
  • Examining your body for swelling or other signs of extra fluid, which may be linked to heart or kidney problems
  • Measuring your blood pressure and oxygen levels

Diagnostic tests and procedures

To diagnose ARDS, your doctor may have you undergo some of the following tests and procedures. Different tests may be appropriate for different ages.

  • Blood tests measure the oxygen level in your blood using a sample of blood taken from an artery. A low blood oxygen level might be a sign of ARDS. In order to confirm the cause of your symptoms, your doctor may also check your blood for signs of infection or a heart problem, or to see how well other organs are working.
  • Chest X-ray to create detailed images of the inside of your chest. This test is generally the standard for showing excess fluid in your lungs.
  • CT (computed tomography) scan of the chest or abdomen to create detailed images of your lungs or check for abdominal infections.
  • Other tests of blood oxygen levels, such as pulse oximetry, do not require collecting a blood sample. For these tests, a sensor is attached to the skin or placed on a hand or foot.

Tests for other medical conditions

Other tests can help find the cause of your ARDS or determine if there is another type of problem. These include:

  • Sputum culture to help find the cause of an infection. The culture is used to study the phlegm you have coughed up from your lungs.
  • Bronchoscopy to diagnose a lung problem when there is no clear cause of your ARDS. As part of this test, your doctor may rinse an area of your lung to get cells and examine them under a microscope or with other tests.
  • Echocardiogram or a lung ultrasound. These tests can help your doctor rule out heart failure, congenital heart defects, or other breathing problems.
  • Lung biopsy, when other tests do not confirm a diagnosis
  • Urine test to detect bacterial infections or rule out kidney problems


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How is ARDS treated?

The goal of treatment for ARDS is to improve oxygen levels and treat the underlying cause. Other treatments aim to prevent complications and make you comfortable.

Breathing support

Oxygen therapy to raise the oxygen levels in your blood is the main treatment for ARDS. Oxygen can be given through tubes resting in your nose, a face mask, or a tube placed in your windpipe.

Depending on the severity of your ARDS, your doctor may suggest a device or machine support your breathing. These include:

  • Non-invasive ventilation, such as bilevel positive airway pressure (BiPAP) or continuous positive airway pressure (CPAP) devices. These electronic breathing devices help keep your airways open by blowing air through a face mask.
  • A ventilator. Your doctor will adjust the ventilator settings to help prevent any more damage to your lung tissue. If the ventilator helps restore your blood oxygen levels and it is easier to breathe on your own, your doctor may turn off the ventilator to see if you are ready for it to be removed completely. Some people transition from a ventilator to portable oxygen therapy. Risks from being on a ventilator include pneumonia and pneumothorax, which can cause your lungs to collapse.


Your doctor may recommend medicine to relieve symptoms, treat the underlying cause, or prevent complications from being in a hospital. These may include:

  • Acid-reducing medicines to prevent stress ulcers, which can cause bleeding in the intestines.
  • Antibiotics to treat or prevent infections. If you are on a ventilator, your healthcare team may do tests, such as lung fluid lab tests or CT scans, to look for signs of a new infection.
  • Blood thinners to stop blood clots from forming or growing larger. Heparin is a common blood thinner for adults.
  • Muscle relaxants help prevent coughing or gagging while on a ventilator or reduce the amount of oxygen your body needs.
  • Pain medicines, which your doctor may prescribe, depending on your needs.
  • Sedatives to help relieve anxiety, make it easier to breathe on a ventilator, or lower your body’s oxygen needs. Sometimes your doctor may pair a sedative with another medicine to make it easier to deliver the oxygen. Complications vary depending on the sedative used, the dose, and how long it is used. They can include depression, post-traumatic stress disorder (PTSD), problems with thinking or memory, or a delay in removing the ventilator.

Other treatments

Your doctor may recommend other treatments, including:

  • Blood transfusion to treat low hemoglobin levels. Hemoglobin carries oxygen in the blood, so a transfusion can improve the delivery of oxygen to the body’s organs.
  • Extracorporeal membrane oxygenation (ECMO) or a similar device, especially for severe ARDS. ECMO helps when ventilation alone cannot deliver enough oxygen or while a patient waits for a lung transplant. ECMO works like an artificial lung, removing carbon dioxide and pumping oxygen-rich blood back into the body.
  • Fluid management. Your healthcare team will monitor the fluid balance in your body. Low blood pressure can occur when the fluid in your blood vessels is low. This may prevent oxygen from getting to your organs. To help restore the balance, your doctor may give you fluid through an intravenous (IV) line. When you have too much fluid in the lungs, your doctor may give you medicines that help your body get rid of it.
  • Nutritional support. You may need a feeding tube to make sure you get enough of the right nutrients while you are on a ventilator.
  • Physical therapy to maintain muscle strength and prevent sores from forming. Movement may help shorten the time you are on a ventilator and improve recovery after you leave the hospital.
  • Positioning your body. For severe ARDS, your doctor may recommend that you spend most of the time lying facedown, which helps oxygen get to more of your lungs.

What are the complications from ARDS?

If you have ARDS, you can develop other medical problems while in the hospital. Some can be life-threatening. The most common problems are:

  • Atelectasis is when small air pockets in the lung collapse
  • Complications of treatment in a hospital. Such complications include blood clots that can form from lying down for long periods, weakness in muscles used for breathing or moving around, infections, stress ulcers, and depression or other mood disorders. Problems with thinking, memory, and judgment also can result from the long-term use of sedative medicines.
  • Failure of multiple organs. The body’s organs may not work as well or may stop working altogether if they do not get enough oxygen. This lack of oxygen may cause several organs to stop working at the same time, setting up a potentially life-threatening situation.
  • Pulmonary hypertension, or an increase in blood pressure in the major artery leading from the heart to the lungs. This condition may occur when the blood vessel narrows as a result of damage from inflammation or mechanical ventilation. ARDS may also cause tiny clots to form in blood vessels in the lungs.

Learn more about how some people are more at risk of complications from ARDS.

  • Some studies indicate that the risk of life-threatening complications may be linked to race or ethnicity. They suggest that African Americans and Hispanics who develop ARDS are less likely than whites to survive. Research also indicates that men with ARDS are more likely than women to develop life-threatening problems.

Living with ARDS

Some people fully recover from ARDS. Others continue to have health problems. After you go home from the hospital, you may have one or more of the following problems:

  • Shortness of breath. After treatment, many people who have ARDS recover close-to-normal lung function within 6 months. For others, it may take longer. Some people have breathing problems for the rest of their lives.
  • Tiredness and muscle weakness. Being in the hospital and on a ventilator (a machine that supports breathing) can cause your muscles to weaken. You also may feel very tired following treatment.
  • Depression. Many people who've had ARDS feel depressed for a while after treatment.
  • Problems with memory and thinking clearly. Certain medicines and a low blood oxygen level can cause these problems.

These health problems may go away within a few weeks, or they may last longer. Talk with your doctor about how to deal with these issues. Also, see the suggestions below.

Getting Help

You can take steps to recover from ARDS and improve your quality of life. For example, ask your family and friends for help with everyday activities.

If you smoke, quit. Smoking can worsen lung problems. Talk to your doctor about programs and products that can help you quit. Also, try to avoid secondhand smoke and other lung irritants, such as harmful fumes.

If you have trouble quitting smoking on your own, consider joining a support group. Many hospitals, workplaces, and community groups offer classes to help people quit smoking.

Go to pulmonary rehabilitation (rehab) if your doctor recommends it. Rehab might include exercise training, education, and counseling. Rehab can teach you how to return to normal activities and stay active.

Your rehab team might include doctors, nurses, and other specialists. They will work with you to create a program that meets your needs.

Emotional Issues and Support

Living with ARDS may cause fear, anxiety, depression, and stress. Talk about how you feel with your health care team. Talking with a professional counselor also can help. If you're very depressed, your doctor may recommend medicines or other treatments that can improve your quality of life.

Joining a patient support group may help you adjust to living with ARDS. You can see how other people who have the same symptoms have coped with them. Talk to your doctor about local support groups or check with an area medical center.

Support from family and friends also can help relieve stress and anxiety. Let your loved ones know how you feel and what they can do to help you.

What is the prognosis and survival rate for ARDS?

More people are surviving ARDS now than in the past. One likely reason for this is that treatment and care for the condition have improved. Survival rates for ARDS vary depending on age, the underlying cause of ARDS, associated illnesses, and other factors. Some studies estimate that the mortality rate for ARDS is 36% to 52% per 100,000 people, depending upon their current health condition.

Some people who survive recover completely. Others may have lasting damage to their lungs and other health problems.

Researchers continue to look for new and better ways to treat ARDS.

What are other names for ARDS?

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National Institutes of Health. ARDS"What Is ARDS?" Updated: Jan 12, 2012.

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