What are the Symptoms of Oxygen Toxicity?

nausea, stomach pain, oxygen toxicity, oxygen, o2Oxygen 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?  Let’s explore this further.

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 where the patient is exposed to very high concentrations of oxygen for short periods of time (e.g. hyperbaric oxygen therapy); the second where lower concentrations of oxygen are used, but for longer periods of time. These lead to what we often refer to as acute (sudden onset) and chronic (persistent, ongoing) oxygen toxicity. The acute effects often manifest as CNS symptoms while chronic effects manifest in the lungs.2

Symptoms of Oxygen Toxicity

Symptoms of oxygen toxicity are most dramatic in the central nervous system (brain and spinal cord) and the lungs and 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 seen. If exposure to oxygen continues, vertigo and nausea occur, followed by behavioral changes (irritability, anxiety, confusion), clumsiness and finally convulsions. It’s 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 a cough. Extreme cases may result in permanent scarring (fibrosis) of the lung tissue that is irreversible.[3]


The average patient using oxygen therapy according to their doctor’s instructions is not at risk for oxygen toxicity. Those at highest risk for oxygen toxicity include deep sea divers, hospital patients, especially 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

For more information about oxygen toxicity, talk to your primary care provider.


[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 India57(2), 131–133. http://doi.org/10.1016/S0377-1237(01)80133-7

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

2 thoughts on “What are the Symptoms of Oxygen Toxicity?”

  1. Curious says:

    Can a high altitude resident experience a degree of such toxicity if flying to a sea level destination with a sudden landing?

    1. Inogen Inogen says:

      Hi Curious, To answer your questions briefly, no, but if this is a concern of yours you should consult your primary care doctor before you fly. When you fly on commercial airlines, the cabins are pressurized to avoid changes in altitude. The people at the highest risk for oxygen toxicity are deep sea divers, hospital patients, especially infants born prematurely who need supplemental oxygen and people who are undergoing hyperbaric oxygen therapy for carbon monoxide poisoning, cyanide poisoning, etc.

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