What Is a Dangerous Blood Oxygen Level?


One of the things that drive our bodies is oxygen. Not only is oxygen in the air we breathe, but it is also circulating constantly through our blood. People need highly oxygenated blood at all times to be healthy and for survival. If your blood oxygen level drops to an unsafe point, it is a condition known as hypoxemia, which is life-threatening. Read on to learn more about blood oxygen levels, what is a normal level, and when you should be concerned.

Learning About Blood Oxygen Levels

Most patients don’t monitor their blood oxygen levels every day. The only time your oxygen likely gets checked is at a physical examination, a routine doctor’s appointment, or if your physician suspects a problem. Those who do need to closely monitor their oxygen levels likely already have an underlying condition, such as chronic obstructive pulmonary disease (COPD), asthma, or heart disease. Normal and abnormal levels may be different for patients who suffer from these conditions.

How Is Blood Oxygen Measured?

In most cases, your healthcare provider will likely use a pulse oximeter. This is a tiny device that fits over your finger, although it can be used on the toes if necessary, and it measures your blood oxygen level in your capillaries via infrared light. This is a simple device to use, which is why it’s used more often than other methods, but it does have a 2 percent margin of error. For those who may be hovering at the low end of the blood oxygen level, this can be a concern. In this case, your physician may use a blood test known as arterial blood gas (ABG), which more accurately measures your blood oxygen level. However, low blood oxygen may be an emergency, and waiting for blood test results may take time. 

What Are Normal Blood Oxygen Levels?

For healthy patients with no other conditions, a blood oxygen level should be between 95 and 100 percent. You can never have a reading that is too “high” when it comes to blood oxygen ― 100 is perfect. Patients who have COPD or other conditions may have a lower blood oxygen level, which is considered normal and not life-threatening to them.

What Are Low or Dangerous Blood Oxygen Levels?

Unless you have a preexisting condition, any reading below 95 percent is considered low. This may or may not be regarded as dangerous, based on your physician’s opinion and current state of health. If you have a reading below 95 percent on an oximeter, your physician will order the ABG test and will want to monitor you more closely. Hypoxemia is the term for low blood oxygen. A value below 90 percent, however, may be cause for concern.

What Are Hypoxemia Symptoms?

If you feel that your blood oxygen level may be low, you should go to an urgent care facility, your physician, or the emergency room immediately. Some common symptoms of hypoxemia to be mindful of include headache, shortness of breath, dizziness, high blood pressure, chest pain, and confusion, among others.

What Causes Low Blood Oxygen?

There can be many causes of low blood oxygen. Some may not be health-related and may be situational, such as being at a high elevation where there is not enough oxygen in the air. It may also be caused by a lung condition or by the inability of the oxygen to be circulated through the bloodstream properly. Conditions that can cause hypoxemia include asthma, COPD, anemia, heart disease, pneumonia, sleep apnea, or fluid in the lungs. Medications such as narcotics can cause low blood oxygen.