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Low blood oxygen (hypoxemia)

Medically reviewed by Last updated on Mar 24, 2023.


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 a problem tied to breathing or blood flow. It may lead to symptoms such as:

A healthy level of oxygen in the arteries is about 75 to 100 millimeters of mercury (mm Hg). Hypoxemia is any value under 60 mm Hg. Levels of oxygen and the waste gas carbon dioxide are measured with a blood sample taken from an artery. This is called an arterial blood gas test.

Most often, the amount of oxygen carried by red blood cells, called oxygen saturation, is measured first. It is measured with a medical device that clips to the finger, called a pulse oximeter. Healthy pulse oximeter values often range from 95% to 100%. Values under 90% are considered low.

Often, hypoxemia treatment involves receiving extra oxygen. This treatment is called supplemental oxygen or oxygen therapy. Other treatments focus on the cause of hypoxemia.


You might learn you have hypoxemia when you see a doctor for shortness of breath or another breathing-related problem. Or you might share the results of an at-home pulse oximetry test with your doctor.

If you use a pulse oximeter at home, be aware of factors that can make the results less accurate:

If you have hypoxemia, the next step is to figure out its cause.

Hypoxemia can be a sign of problems such as:

Causes of hypoxemia that are related to problems with blood or blood flow include:

Breathing conditions that can lead to hypoxemia include:

Some medicines that can cause slow, shallow breathing can lead to hypoxemia. These include certain opioid pain relievers and medicines that prevent pain during surgery and other procedures, called anesthetics.

When to see a doctor

Seek emergency care if you have shortness of breath that:

See your doctor as soon as possible if you:


These tips could help you cope with ongoing shortness of breath:

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