Hypoxemia is a low level of oxygen in the blood. It starts in blood vessels called arteries. Hypoxemia isn't an illness or a condition. It's a sign of an issue tied to breathing or blood flow.
Hypoxemia may lead to:
- Shortness of breath.
- Fast breathing.
- Fast or pounding heartbeat.
- Not thinking clearly.
A healthy level of oxygen in the arteries is about 75 to 100 millimeters of mercury (mm Hg). Healthcare professionals use a sample of blood taken from an artery to measure levels of oxygen and the waste gas carbon dioxide. This is called an arterial blood gas test.
Most often, the first measure is the amount of oxygen that red blood cells carry. This is called oxygen saturation. A medical device that clips to the finger, called a pulse oximeter, measures oxygen saturation. Healthy pulse oximeter values range from 95% to 100%. Values under 90% are low.
Often, hypoxemia treatment involves getting extra oxygen. This treatment is called supplemental oxygen or oxygen therapy. Other treatments focus on the cause of hypoxemia.
You may learn you have hypoxemia when you see a healthcare professional for shortness of breath or another breathing-related condition. Or you might share the results of an at-home pulse oximetry test with your healthcare professional.
If you use a pulse oximeter at home, know that the following can make the results less exact:
- Poor blood flow, also called poor circulation.
- Black or brown skin color.
- Tobacco use.
- Fingernail polish.
If you have hypoxemia, the next step is to figure out its cause.
Seek emergency care if you have shortness of breath that:
- Comes on fast, affects how well you can do daily tasks or happens with symptoms such as chest pain
- Happens at an elevation above 8,000 feet (about 2,400 meters) and comes with a cough, fast heartbeat or weakness. These are symptoms of fluid leaking from blood vessels into the lungs, called high-altitude pulmonary edema. This can be deadly.
See your healthcare professional as soon as you can if you:
- Become short of breath after slight physical effort or when you're at rest.
- Have shortness of breath that you don't expect from a certain activity, given your fitness and health.
- Wake up at night with a gasp or a feeling that you're choking. This may be a symptom of sleep apnea, a condition in which breathing starts and stops during sleep.
Self-care
These tips could help you cope with continued shortness of breath:
- If you smoke, quit. This is one of the most important things you can do if you have hypoxemia. Smoking makes medical conditions worse and harder to treat. For help quitting, talk with your healthcare professional.
- Stay away from secondhand smoke. Don't be around others who smoke. It can cause more lung damage.
- Get regular exercise. Ask your healthcare professional what activities are safe for you. Regular exercise can boost your strength and help you endure hard effort.
Show References
- Theodore AC. Measures of oxygenation and mechanisms of hypoxemia. https://www.uptodate.com/contents/search. Accessed Oct. 6, 2025.
- AskMayoExpert. Hypoxemia. Mayo Clinic; 2023.
- Breathlessness: Shortness of breath. American Thoracic Society. https://www.thoracic.org/search.php?cx=007982365765420951334%3A7u3jtkdzuqu&cof=FORID%3A10&ie=UTF-8&q=shortness%20of%20breath&sa=&siteurl=www.thoracic.org%2F&ref=&ss=0j0j1#. Accessed Oct. 7, 2025.
- Sood S. Evaluation and management of the nonventilated, hospitalized adult patient with acute hypoxemia. https://www.uptodate.com/contents/search. Accessed Oct. 7, 2025.
- Learn about shortness of breath. American Lung Association. https://www.lung.org/lung-health-diseases/warning-signs-of-lung-disease/shortness-of-breath/diagnosing-treating. Accessed Oct. 7, 2025.
- Pulse oximetry. American Lung Association. https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/pulse-oximetry. Accessed Oct. 7, 2025.
Original article: https://www.mayoclinic.org/symptoms/hypoxemia/basics/definition/sym-20050930