What Are the Symptoms of Oxygen Toxicity?

nausea, stomach pain, oxygen toxicity, oxygen, o2

Oxygen therapy is a lifesaver for people with COPD and other chronic (ongoing) illnesses, its benefits known to increase survival, relieve symptoms, increase exercise tolerance, improve health-related quality of life and more.[1] But what happens when you get too much oxygen? And under what circumstances could this occur? Learn the symptoms of too much oxygen and what it means to have oxygen toxicity.

History of “Pure Air”

Oxygen has existed in our atmosphere for 5 billion years, its concentration insignificant until approximately 2.5 billion years ago when the first photosynthetic organisms appeared. Joseph Priestly, the man who discovered oxygen in 1774, was one of the first to propose that adverse events may be associated with this “pure air” we now know as oxygen. But it wasn’t until 1878 that the first important contribution in the field of oxygen toxicity was made when Paul Bert, a French physiologist, demonstrated the effects of oxygen toxicity on larks. To this day, the toxic effects of oxygen on the central nervous system (CNS) are referred to as the “Bert Effect.”[2]

Who’s at Risk for Oxygen Toxicity?

In general, there are two medical settings in which oxygen toxicity might exist. The first scenario could occur anywhere the patient is exposed to very high concentrations of oxygen for short periods of time (e.g. hyperbaric oxygen therapy). The second scenario could occur where lower concentrations of oxygen are used, but for longer periods of time. These two situations could lead to what we often refer to as acute (sudden onset) and chronic (persistent, ongoing) oxygen toxicity. The acute effects often manifest as central nervous system (CNS) symptoms while chronic effects manifest in the lungs.[2]

Signs and Symptoms of Oxygen Toxicity

Signs and symptoms of oxygen toxicity are most dramatic in the central nervous system (brain and spinal cord) and the lungs, and can include the following:

    • CNS toxicity – early symptoms of CNS toxicity tend to come on suddenly and include twitching around the mouth area and small muscles of the hand. Facial pallor (ashen hue) and cogwheel breathing (peculiar, jerky inhalations) are also oxygen toxicity signs, along with headache, hiccups, shivering, tingling in the limbs, vision and hearing changes, fatigue and hyperventilation. If exposure to oxygen continues, vertigo and nausea occur, followed by behavioral changes (irritability, anxiety, confusion), clumsiness and finally convulsions. It is important to note that CNS toxicity is often accelerated by factors such as increased carbon dioxide in the blood, stress, fatigue and cold.[2]
    • Pulmonary toxicity – symptoms of pulmonary toxicity affect the lower respiratory tract including the trachea (windpipe), bronchi (air passages) and lungs. The initial sign of pulmonary oxygen toxicity manifests as a generalized pain behind the sternum (breastbone). This pain often becomes widespread, increases in intensity and is accompanied by an uncontrollable cough. Other pulmonary symptoms of too much oxygen include fever, rattling on the inhale, a tickling or burning sensation on the inhale, coughing up blood and labored breathing. Extreme cases may result in permanent scarring (fibrosis) of the lung tissue that is irreversible.[3]

Other oxygen toxicity signs include retinal edema and cataract formation with long-term exposure

Diagnosing Oxygen Toxicity Signs

Patients who are at a higher risk of developing oxygen toxicity because of long-term oxygen therapy or exposure to high concentrations of oxygen must be carefully monitored for signs and symptoms of oxygen toxicity throughout their treatment. Health care providers will check patients’ oxygen saturation regularly, as well as watching for any changes in breathing. Pulmonary function testing may take place to check for signs of respiratory distress. In addition, since some oxygen overdose symptoms are ocular in nature, eye exams may occur as well. If there are symptoms of too much oxygen present, oxygen treatment may be slowed or halted until the patient is stabilized. 

Treating Oxygen Toxicity

First and foremost, when oxygen toxicity signs appear, the exposure to the oxygen must be reduced right away. In most cases, this is enough to mitigate the oxygen overdose symptoms. Doctors are extremely careful to prescribe and administer the lowest possible concentrations of oxygen that still offer therapeutic benefits in order to avoid any symptoms of too much oxygen. Additionally, it is extremely rare for patients receiving oxygen therapy at home to show any signs or symptoms of oxygen toxicity. Still, oxygen toxicity is serious and as such, it is vital that you follow your doctor’s orders when receiving oxygen therapy and never adjust your dosage, flow rate or amount of time receiving oxygen treatment without first talking with your doctor. 

Are Oxygen Therapy Patients at Risk for Oxygen Toxicity?

The average patient using oxygen therapy according to their doctor’s instructions is not at risk for oxygen toxicity. Those at the highest risk for oxygen toxicity include deep sea divers, hospital patients, infants born prematurely who need supplemental oxygen and people who are undergoing hyperbaric oxygen therapy for carbon monoxide poisoning, cyanide poisoning and a host of other conditions.3 However, most supplemental oxygen patients are using a low enough oxygen concentration to have very little risk. Regardless, it is a good idea to be familiar with the symptoms of too much oxygen and oxygen toxicity signs. If you are at all concerned about potential oxygen overdose symptoms, call your doctor. If you or a loved one is experiencing signs and symptoms of oxygen toxicity, seek medical attention right away.

For more information about the symptoms of too much oxygen and oxygen toxicity, talk to your primary care provider.

Frequently Asked Questions: Oxygen Toxicity

Can you get too much oxygen from a machine?

It is possible to get too much oxygen from an oxygen concentrator machine. However, this is quite rare when oxygen concentrators are used as directed and prescribed. All supplemental oxygen requires a prescription from a doctor, who carefully chooses your oxygen prescription. Doctors prescribe the lowest possible concentration to their patients that will still provide therapeutic benefits in order to avoid symptoms of too much oxygen. While oxygen toxicity is still technically a risk, particularly for patients who will be using supplemental oxygen for an extended period of time, the risk is quite low when used as directed. It is vital, therefore, that patients never adjust their flow rate or the amount of time they use supplemental oxygen without first talking to their doctor. 

Can you die from too much oxygen?

Yes, but it would likely take days of excessive exposure to pure oxygen. If you have been exposed to high concentrations of oxygen already, or if you have been exposed to higher concentrations of oxygen over time, continued exposure could lead to oxygen toxicity and could be life-threatening. However, oxygen toxicity signs are usually clear enough to indicate a serious problem before it becomes life-threatening. 


[1] Stoller, James K. MD, MS, FCCP et. al. Oxygen Therapy for Patients With COPD: Current Evidence and the Long-Term Oxygen Treatment Trial. Chest. 2010 July; 138(1): 179–187. doi: 10.1378/chest.09-2555. PMCID: PMC2897694.

[2] CHAWLA, A., & LAVANIA, A. (2001). OXYGEN TOXICITY. Medical Journal, Armed Forces India, 57(2), 131–133. http://doi.org/10.1016/S0377-1237(01)80133-7

[3] Campbell, Ernest S., MD. Pulmonary Oxygen Toxicity. January 23, 2002.

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