Hypoxia: Causes, Symptoms, Tests, Diagnosis & Treatment

Written By: Dr. Fabrizio Facchini

Dr. Fabrizio Facchini is a Consultant in the Department of Pulmonology at Medcare Hospital, Al Safa. After completing his basic medical education he obtained an MD from the University of Ferrara in Italy. He is a Clinical & Research Fellow from the University College London in the UK and a Specialist in Pulmonary Diseases and Phthisiology from the University of Ferrara in Italy. He is Board Certified from ODM - Italy; GMC - UK; DHA - UAE.

Updated On:January 24, 2024

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 Hypoxia: Causes, Symptoms, Tests, Diagnosis & Treatment

What is Hypoxia?

Hypoxia occurs when the tissues in your body don't get enough oxygen. When you breathe, oxygen enters your lungs where it passes through your airways and into tiny sacs called alveoli before leaving your body. Your blood picks it up from there in tiny channels that move close to the alveoli (capillaries). Ultimately, it goes through your blood out to different tissues.

 Causes of Hypoxia

Hypoventilation, ventilation-perfusion mismatch, low air oxygen content, right-to-left shunting, or impeded diffusion are some of the traditional causes of hypoxia.

Most frequently, an underlying ailment interferes with breathing or blood flow and causes hypoxia. These conditions may include asthma, bronchitis, sleep apnea, and pneumonia, among others.

Symptoms of Hypoxia

Depending on the intensity, underlying cause, and affected body areas, hypoxia manifests itself in a variety of ways. You can feel like you can't breathe or think clearly when your oxygen levels are low. Some signs of hypoxia include the following:

  • Restlessness
  • Headache
  • Confusion
  • Anxiety
  • Quick heartbeat (tachycardia)
  • Quick breathing (tachypnea)
  • Respiratory issues or lack of breath (dyspnea)
  • Sluggish heartbeat (bradycardia)
  • Extreme agitation
  • Cyanosis (Bluish discoloration to the skin)

 Types of Hypoxia

For healthy lung functioning and for oxygen to reach the cells in your tissues, you would need sufficient oxygen levels in the air you breathe. Moreover, circulatory and cardiac health are necessary for delivering oxygen-rich blood to your tissues so are sufficient red blood cells to carry oxygen.

Each of the four forms of hypoxia is brought on by a deficiency of oxygen in one of the regions mentioned above.

  • Hypoxemic Hypoxia

Hypoxemic hypoxia, the most typical type of hypoxia, can result from low blood oxygen levels (hypoxemia). Lung and heart conditions, congenital cardiac problems, and drugs that slow breathing can all contribute to hypoxemia. Hypoxemia can also result when ascending to a high altitude, where oxygen concentrations are lower.

  • Circulatory Hypoxia

If the heart is not pumping enough blood or if a blood vessel is blocked, even though your blood contains enough oxygen, it may not reach your tissues. The term for this is circulatory hypoxia (also called stagnant hypoxia or ischemia hypoxia). The risk of circulatory hypoxia may increase if you have blood clots or congestive heart failure.

  • Anemic Hypoxia

When there are insufficient red blood cells to transport oxygen from your lungs to other tissues, anemic hypoxia occurs. If your body produces too few or abnormally shaped red blood cells, you could become anemic.

  • Histotoxic Hypoxia

When your cells are unable to use oxygen effectively, histotoxic hypoxia occurs. In this situation, you can have a lot of oxygen entering your blood and your lungs. However, something prevents your cells from using it when it reaches your tissues. With cyanide poisoning, this is possible.

When to see a doctor for Hypoxia?

You should get medical help right away if you exhibit symptoms like dizziness, shortness of breath, or a racing heartbeat, or if you notice that your lips, nails, or skin are turning blue. A pulse oximeter allows you to check your oxygen levels at home. In cases of severe hypoxia, immediate treatment is necessary to avoid organ damage.

Hypoxia Risk Factors

Hypoxia can be brought on by any condition that limits blood flow or lowers the amount of oxygen in your blood. Individuals who have heart or lung conditions, such as COPD, emphysema, or asthma, are more likely to experience hypoxia. You run a higher chance of developing hypoxia if you have certain infections, such as COVID-19, influenza, or pneumonia.

Hypoxia Complications

To produce energy and support the function of your organs and tissues, your cells require oxygen. Although certain of your tissues may adapt to brief drops in oxygen levels, sustained hypoxia can harm your organs. Damage to the heart and brain is highly hazardous and fatal. Cerebral hypoxia refers to a lack of oxygen reaching the brain.

Hypoxia Diagnosis

Your medical professional will conduct a physical examination, which will include listening to your heart and lungs. They might examine your lips, nails, and skin to see if they have a blue tint. In order to monitor your oxygen levels and identify the underlying cause of hypoxia, your doctor could also request the following tests:

  • Your healthcare professional will place a sensor over your finger to measure the amount of oxygen in your blood using pulse oximetry. It is a non-invasive, painless process, known as pulse oximetry.
  • A tiny needle is used to draw blood from your wrist, arm, or groin to perform an arterial blood gas test (ABG), which measures your blood's oxygen content.
  • When you perform a pulmonary function test (PFT), a mouthpiece that is connected to a machine assesses how well your lungs are functioning.
  • Images of your internal organs can be obtained using imaging techniques such as X-rays, CT scans, and V/Q scans. Your doctor can identify the source of hypoxia with the aid of imaging.
  • The six-minute walk test (6MWT) involves walking for six minutes straight on a flat surface to determine how far you can move. Your healthcare professional can assess lung and heart function using this test.

Hypoxia Treatment

The underlying cause of hypoxia will determine the course of treatment. The cause could be a recurring issue or a one-time occurrence. Possible treatments include:

  • Steroids that are inhaled can widen your airways and treat lung conditions including asthma.
  • Medications that ease the burden of extra pulmonary fluid (diuretics).
  • To cure sleep apnea, use a continuous positive airways pressure mask (CPAP).
  • BiLevel positive airway pressure, also referred to as BiPAP®, is used to treat some forms of sleep apnea and COPD.
  • Treatment of continuing (chronic) hypoxia with additional oxygen. To boost the amount of oxygen reaching your lungs and alveoli, an oxygen delivery system is attached to your nose via a mask or tubes.
  • When there is severe acute hypoxia, mechanical ventilation is used in hospitals.

 Hypoxia Prevention

Taking care of any underlying issues that can cause your oxygen levels to drop is the greatest method to lessen your risk of hypoxia. If you have a heart or lung issue, discuss your worries and special precautions with your healthcare professional. Be aware that some conditions, like going to a higher altitude, and drugs may make you more susceptible to hypoxia. Inquire with your doctor whether there are any extra safety measures you should take before traveling or switching medications.


Bhutta, B. S., Alghoula, F., & Berim, I. (2022). Hypoxia. In StatPearls [Internet]. StatPearls Publishing.

Cafaro, R. P. (1960). Hypoxia: its causes and symptoms. Journal of the American Dental Society of Anesthesiology7(4), 4.

Schaffer, K., & Taylor, C. T. (2015). The impact of hypoxia on bacterial infection. The FEBS journal282(12), 2260-2266.

Tirpe, A. A., Gulei, D., Ciortea, S. M., Crivii, C., & Berindan-Neagoe, I. (2019). Hypoxia: overview on hypoxia-mediated mechanisms with a focus on the role of HIF genes. International journal of molecular sciences20(24), 6140.

Meet our doctors from the Pulmonology department

Assem Eid Youssef
MRCP (UK), MBBS, MD, Master (Respiratory medicine)
Arabic, English
Mohammed Harriss
Arabic, English, Hindi, Malayalam
Fabrizio Facchini
English, Italian
Emadeldin Ibrahim
MBBCh, MSc in Chest Diseases, MD (Chest Diseases)
Arabic, English
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