If you are experiencing severe shortness of breath, changes in skin color, confusion, or rapid heart rate, call 911 immediately.

Hypoxemia occurs when there are low oxygen levels in the arterial blood. It is typically caused by another medical condition, particularly those that affect the respiratory and circulatory systems. There are treatments for hypoxemia but the underlying cause must also be treated. If left untreated, hypoxemia can cause serious health problems and even death.

This article discusses hypoxemia’s symptoms, possible causes, diagnosis, complications, and treatments.

a person outside, closing their eyes and presumably focusing on their breathing

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Symptoms of Hypoxemia

Common symptoms of hypoxemia are:

  • Shortness of breath or rapid breathing
  • Wheezing
  • Cough
  • Confusion
  • Increased heart rate
  • Changes in skin color, including blue lips and nails

Causes of Hypoxemia

Hypoxemia is usually caused by a medical condition that leads to decreased oxygen in the blood. Because the respiratory and cardiovascular symptoms are the two main systems responsible for delivering oxygen to the body, conditions that affect these systems are common causes of hypoxemia.

Causes of hypoxemia include:

Asthma, COPD, and other lung conditions can affect the airflow in and out of the lungs. Infections that affect the respiratory system, such as pneumonia and COVID-19, can also cause hypoxemia. When the lungs aren't able to take air in and out as they should, the blood doesn't receive enough oxygen.

If the heart is not pumping efficiently, a lack of oxygen-rich blood is being delivered to the body, which can cause hypoxemia. Some heart conditions, such as heart failure, can cause fluid to accumulate in the lungs, leading to breathing problems and hypoxemia.

Hypoxemia can occur in newborns with congenital heart defects or disease. One way infants are screened for congenital heart defects is by measuring blood oxygen levels. Preterm infants are vulnerable to hypoxemia, especially if they’ve been placed on a mechanical ventilator.

Obstructive sleep apnea is a chronic condition caused by a relaxation of the muscles in the back of the throat as well as other anatomical factors. People with the condition have brief pauses where they stop breathing during sleep. These pauses can lead to intermittent hypoxemia, a condition where a person transitions between low and normal blood oxygen levels.

What Medications Can Cause Hypoxemia?

Opioids are a class of drugs used to block pain. Common examples include morphine and oxycodone.

Opioids can cause respiratory depression, especially if they are overused or abused. When someone's respiratory rate falls, hypoxemia can develop. People who already have lung disease or obstructive sleep apnea are at an increased risk of respiratory issues during opioid therapy, especially within the first 24 hours of using the drugs.

How to Treat Hypoxemia

The goal of treating hypoxemia is to raise oxygen levels in the blood. A healthcare team may use medications given through an inhaler to treat the condition causing hypoxemia.

Some people may require oxygen therapy, which typically takes place in a hospital. For many people, receiving oxygen through a mask or nose cannula (tube) is enough to restore normal oxygen levels.

Because hypoxemia is a symptom of an underlying medical condition, it is also important to determine and treat the cause of hypoxemia.

Complications and Risk Factors Associated With Hypoxemia

If hypoxemia is not treated and becomes severe, respiratory failure can occur. Untreated hypoxemia can also seriously affect the function of the heart and brain.

Hypoxemia can also lead to a serious condition called hypoxia, or low levels of oxygen in the tissues and organs.

People who experience intermittent hypoxemia due to obstructive sleep apnea may be at an increased risk of cardiovascular disease, metabolic dysfunction, cognitive decline, and cancer progression.

Are There Tests to Diagnose the Cause of Hypoxemia?

To determine what might be causing hypoxemia, a healthcare provider might perform one or more of the following tests:

  • Physical exam: Your healthcare provider will listen to your heart and lungs and examine if your skin, lips, or fingernails are blue.
  • Tests to determine blood oxygen levels include pulse oximetry, where a sensor is placed on your finger to measure the amount of oxygen in the blood, and an arterial blood gas test that uses a blood sample to measure the blood’s oxygen levels.
  • Lung function tests measure the amount of air you are breathing in and out, how fast you can expel air, and how well your lungs are delivering oxygen. The most common lung function test is called spirometry.

When to See a Healthcare Provider

If you are experiencing symptoms of hypoxemia for the first time, it's important to contact a healthcare provider right away.

Anyone experiencing the following symptoms should seek emergency help:

  • Severe shortness of breath or rapid breathing
  • Increased heart rate
  • Confusion
  • Changes in skin color, including blue skin, lips, or nails


Hypoxemia is a symptom of other medical conditions, or, in some cases, opioid drug use. It is diagnosed through physical exams, tests that measure blood oxygen levels, and, sometimes, lung function tests. Hypoxemia is often successfully treated with medications or oxygen therapy and can cause serious complications if left untreated.

A Word From Verywell

Seek medical help if you are experiencing any of the signs of hypoxemia. Medications and oxygen treatment are enough to bring blood oxygen levels back to normal for many people. However, it is important to also find and treat the condition causing hypoxemia. Work with your healthcare provider to manage any underlying causes, and ask if there are steps you can take to prevent hypoxemia from occurring again.

Frequently Asked Questions

  • What causes hypoxemia?

    The most common causes of hypoxemia are conditions that affect the respiratory or circulatory systems. Obstructive sleep apnea is another cause of hypoxemia.

  • Can anything besides a medical condition cause hypoxemia?

    Yes. Opioids can also cause hypoxemia, especially if they are abused. Spending time at high altitudes where there is less oxygen in the air can also cause hypoxemia, especially during exercise.

  • Is hypoxemia a symptom of COVID-19?

    When COVID-19 is severe, it can cause difficult or labored breathing, which is often accompanied by hypoxemia. Severe illness typically occurs about one week after the onset of COVID-19 symptoms.

12 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cathy Nelson
Cathy Nelson has worked as a writer and editor covering health and wellness for more than two decades. Her work has appeared in print and online in numerous outlets, including the Detroit Free Press and The Detroit News.