Normal Blood Oxygen Levels: What Is Safe, And What Is Low?

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Medical News TodaySubscribeWhat is a normal blood oxygen level and how do doctors treat low blood oxygen?

Medically reviewed by Lauren Castiello, MS, AGNP-C — Written by Joana Cavaco Silva — Updated on January 25, 2024

Normal levels
Low blood oxygen
Oxygen saturation
Measurement process
Symptoms
Causes
Contacting a doctor
Treatment
Outlook
FAQ
Summary

Blood oxygen levels refer to the amount of oxygen circulating in the blood. Normal blood oxygen levels fall between 75 and 100 millimeters of mercury (mm Hg) on arterial blood gas (ABG) test results.

A person’s blood oxygen level indicates how well the body distributes oxygen from the lungs to the cells.

If someone’s blood oxygen level falls below 60 mm Hg, there may not be enough oxygen reaching the body’s vital organs. This can lead to symptoms such as shortness of breath and dizziness.

This article explains the expected blood oxygen level, what happens when blood oxygen is low, how blood oxygen is measured, and more.

What is the expected blood oxygen level?

a woman breathless on an exercise bike who may have low or normal blood oxygen levels-1 — Hiraman/Getty Images

The body regulates oxygen levels to ensure vital organs receive enough oxygen to function normally.

A healthy blood oxygen level, according to ABG test results, ranges between 75 and 100 mm Hg. This range indicates no abnormalities in a person’s blood oxygen level.

What is a low blood oxygen level, and what does it mean?

When ABG test results reveal an oxygen level below 60 mm Hg, doctors may consider a person to have low blood oxygen. In some cases, people with these results may require oxygen supplementation.

A blood oxygen level that is too low can be a sign of a condition known as hypoxemia. This develops when the body has difficulty delivering oxygen to its cells, tissues, and organs.

What should someone’s oxygen saturation level be?

Oxygen saturation refers to the percentage of oxygen in a person’s blood. Medical professionals can use a device called a pulse oximeter for either a quick test or continuous monitoring.

A healthy oxygen saturation level, according to a pulse oximeter, ranges between 95% and 100%. If a person’s levels drop below this range, they may experience symptoms of low oxygen, including:

trouble breathing
confusion
blue tint to lips or face
difficulty waking up

How do doctors measure blood oxygen levels?

An ABG test is a common way to monitor blood oxygen levels. This test involves taking a blood sample from an artery, usually in the wrist.

This procedure is very accurate, but it can be a little painful. Doctors carry out ABG tests in a hospital. A person cannot perform an ABG test at home.

Pulse oximetry is an alternative, noninvasive method to measure blood oxygen saturation. People can test themselves at home using a pulse oximeter.

A pulse oximeter is a small clip that often attaches to a finger, although it will also work on an ear or a toe. It measures blood oxygen indirectly by light absorption through a person’s pulse.

Although the pulse oximeter test is easier, quicker, and less painful than the ABG test, the following factors can interfere with the results:

bright lights
darker skin tones
nail polish
poor circulation to the extremities

Learn how to choose the best pulse oximeter.

Symptoms of low blood oxygen levels

Low blood oxygen levels can result in abnormal circulation and cause the following symptoms, depending on severity:

shortness of breath
headaches
restlessness
dizziness
rapid breathing
chest pain
confusion
high blood pressure
lack of coordination
visual disorders
rapid heartbeat

Learn more about the symptoms of poor circulation.

What causes low blood oxygen?

The medical term for low blood oxygen is hypoxemia. It may happen due to:

insufficient oxygen in the air
an inability of the lungs to inhale and send oxygen to all cells and tissues
an inability of the bloodstream to circulate to the lungs, collect oxygen, and transport it around the body

Conditions that can lead to hypoxemia

Several medical conditions and situations can contribute to the above factors, including:

asthma
chronic obstructive pulmonary disease (COPD)
interstitial lung disease
pulmonary hypertension
bronchiectasis
emphysema
acute respiratory distress syndrome (ARDS)
pneumonia
obstruction of an artery in the lung
pulmonary fibrosis, or scarring and damage to the lungs
presence of air or gas in the chest that makes the lungs collapse
excess fluid in the lungs

When to contact a doctor about blood oxygen levels

People should contact a doctor if they experience:

severe and sudden shortness of breath
shortness of breath when at rest
severe shortness of breath that worsens during exercise or physical activity
irritability or confusion
a rapid or irregular heartbeat
skin discoloration

These symptoms could indicate that they have low blood oxygen levels.

How do doctors treat low blood oxygen levels?

The treatment options for low blood oxygen levels include supplemental oxygen. Doctors can administer oxygen therapy in an office, or prescribe the use of home oxygen therapy (HOT).

A range of devices are available for delivering and monitoring HOT, but some require a prescription.

People can make lifestyle adjustments to reduce the symptoms of low oxygen levels, and improve their general health and quality of life. Changes that will likely be beneficial include:

quitting smoking
avoiding secondhand smoke
eating a nutritious diet containing plenty of fruits, whole grains, lean protein, and vegetables
exercising regularly

What is the typical outlook for someone with low blood oxygen?

Many conditions can cause low blood oxygen levels. Treating the underlying condition responsible will generally improve blood oxygen levels.

People with chronic lung diseases, such as COPD, and those who catch COVID-19 may need regular blood oxygen monitoring.

People with low blood oxygen can also make lifestyle changes, such as adjusting their dietary and exercise habits. In conjunction with oxygen therapy, these changes could help a person raise their oxygen saturation levels.

Frequently asked questions

Is 92% a good oxygen level?

A healthy oxygen saturation level of 92 is typically low. A pulse oximeter reading should display around 95-100% in most healthy adults and children.

What is a normal oxygen level for COVID-19?

People receiving oxygen therapy for COVID-19 will typically aim for an oxygen saturation of 95%. More intensive treatment may be necessary if oxygen therapy does not help a person achieve this.

Is 94% oxygen OK for older adults?

Summary

A person’s blood oxygen level refers to the amount of oxygen circulating in their blood. A person can measure blood oxygen levels using a pulse oximeter. On a pulse oximeter, doctors consider levels under 95% to be low.

Several conditions can cause low blood oxygen levels, including asthma, anemia, and COVID-19.

The treatment will often involve addressing the underlying cause, but doctors may sometimes also recommend oxygen therapy or lifestyle modifications.

Read the article in Spanish.

Pulmonary System
Respiratory
Blood / Hematology

How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Bhutta BS, et al. (2022). Hypoxia. Castro D, et al. (2022). Arterial blood gas. Coronavirus disease 2019 (COVID-19). (n.d.). COVID-19: How to monitor your oxygen level. (2022). Hafen BB, et al. (2022). Oxygen saturation. Pulse oximeter accuracy and limitations: FDA safety communication. (2022). Röttgering JG, et al. (2021). Determining a target SpO2 to maintain PaO2 within a physiological range. Sarkar M, et al. (2017). Mechanisms of hypoxemia. Torp KD, et al. (2023). Pulse oximetry.https://www.ncbi.nlm.nih.gov/books/NBK482316/

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Medically reviewed by Lauren Castiello, MS, AGNP-C — Written by Joana Cavaco Silva — Updated on January 25, 2024

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