#450: Oxygen Toxicity

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Oxygen therapy, one of the most common interventions in the clinical setting, can actually harm patients when used incorrectly. Though oxygen is essential for life, there is truth in the adage that you can have too much of a good thing. Oxygen toxicity can be acute or chronic. Acute oxygen toxicity occurs with a short duration of very high FiO2 while chronic toxicity occurs when a patient is exposed to lower FiO2 levels for a prolonged duration.

Pathophysiology of oxygen toxicity

Exposure to too much oxygen leads to oxidative damage of cell membranes and, ultimately, alveolar collapse. With high concentrations of oxygen, oxygen-derived free radicals are produced which damage pulmonary tissue, inactivate surfactant, form intra-alveolar edema, and result in complications such as pulmonary atelectasis, tracheobronchitis, hypercapnia, and respiratory failure.

Who is at risk for oxygen toxicity?

Individuals at risk for oxygen toxicity include: 

• Patients receiving prolonged mechanical ventilation
• Any patient receiving > 50% FiO2 for 24 to 48 hours
• Patients on oxygen therapy with PaO2 above normal parameters (normal is 80 to 100 mm Hg)
• Patients receiving hyperbaric oxygen therapy
• Premature infants (due to immature lungs and retinas)
• Underwater divers
• Patients taking certain medications while on oxygen therapy, such as the chemotherapeutic agent bleomycin

L: How does the patient LOOK?

Most of the signs and symptoms of oxygen toxicity are neurological and respiratory in nature. 

Neurological:

• Twitching of the hand and perioral muscles (common early sign)
• Nausea
• Tinnitus (ringing in the ears)
• Dysphoria or feeling of unease
• Headache
• Hiccups
• Irritability, anxiety
• Disorientation, dizziness
• Tingling in the arms and legs
• Hyperventilation
• Seizures

Respiratory:

• Persistent, nonproductive cough
• Mild burning and/or tickling sensation when inhaling
• Shortness of breath
• Coarse lung sounds due to pulmonary edema
• Hemoptysis
• Red and swollen nasal mucosa
• Pleuritic chest pain
• Substernal heaviness
• Lower-than-expected oxygen saturation level

Oxygen toxicity can also affect the eyes, leading to temporary nearsightedness (myopia) and visual disturbances. Long term effects include cataract formation, and retinal edema. In premature infants, oxygen toxicity causes retinopathy of prematurity, which can lead to loss of vision.

A: What ASSESSMENTS are most important for a patient receiving oxygen therapy?

The most important assessments to prioritize when a patient is receiving oxygen therapy center on ensuring the patient is receiving an appropriate concentration of oxygen. Too little and their systems won’t be supported. Too much and they could potentially experience oxygen toxicity. 

Those key assessments are: 

Monitor SpO2 and/or PaO2. In most patients SpO2 should be 95 to 100%, though some patients will have lower parameters. For example, a patient with COPD may have an SpO2 goal of 88%. Likewise, PaO2 should be between 80 to 100 mmHg in an otherwise healthy patient. If the patient has a chronic lung condition such as COPD, then their normal PaO2 may be in the 50s. The key is to know the patient’s specific goal and titrate oxygen to that goal rather than a blanket “normal” number.

Monitor how much oxygen the patient is receiving. When your patient is on a ventilator, BiPAP or CPAP, it’s easy to see the FiO2 because the settings are displayed on the device’s screen. Calculating FiO2 with standard oxygen delivery systems such as nasal cannulas or simple face masks is a bit less obvious.

The general rule of thumb is that FiO2 increases by about 3 to 4% for every liter increase in the flow rate of oxygen. Recall that normal atmospheric FiO2 is 21%. Using this as a standard, you can estimate the approximate FiO2 based on the flow rate of oxygen.

O2 Flow	FiO2
2 L/min	28-29%
4 L/min	36-37%
6 L/min	44-45%
10 L/min	60-61%

Other key assessments include monitoring the patient’s respiratory status and, of course, keeping an eye out for any signs and symptoms of oxygen toxicity.

If your patient is experiencing oxygen toxicity, assessments are geared toward monitoring the severity of symptoms. This can include performing a chest pain assessment, listening to lung sounds, assessing visual acuity, and watching for neurological manifestations. 

T: What TESTS are utilized in oxygen toxicity?

• Arterial blood gas (ABG) – An ABG can show the partial pressure of oxygen in arterial blood, giving a definitive view of hyperoxemia. Remember, a normal PaO2 is 80 to 100 mmHg. If your patient has a PaO2 > 100 mmHg, this is a big clue to titrate the oxygen down.
• Chest X-Ray – The chest x-ray can show pulmonary edema and presence of acute respiratory distress syndrome (ARDS).
• Pulmonary function tests (PFTs) – Tests can show reduced lung compliance, diffusing capacity, and vital capacity
• Eye exams – Testing of visual acuity and opacity of the lens can detect early ocular manifestations of oxygen toxicity. 

T: What TREATMENTS are provided for oxygen toxicity?

The first key treatment is prevention! Always use the lowest amount of FiO2 needed for the patient to reach their oxygenation goal. For example, ARDS protocol utilizes higher levels of PEEP in order to keep FiO2 levels as low as possible. (Not sure what PEEP is? Check out this post here!). 

Aside from prevention, the next best thing you can do is decrease oxygen with the first sign of toxicity, taking note that sudden discontinuation can exacerbate symptoms. Beyond that, treatment for oxygen toxicity focuses on managing the various symptoms. For example, a medication such as levetiracetam would be indicated for a patient having seizures or ondansetron may be used for a patient experiencing nausea. Some studies show that vitamins C and E, which are antioxidants, have been found to reduce the prevalence of retinopathy in newborns.

E: What EDUCATION should be provided?

Since oxygen is a necessity, many patients may believe it’s impossible to overdo it. That’s why a key education point is to teach patients that only the prescribed amount of oxygen should be used. Other important things to highlight in your education plan include:

• The signs and symptoms of oxygen toxicity – this is important for anyone utilizing oxygen over a long-term period at home
• Studies show that long-term neurological damage does not occur and that pulmonary manifestations can be reversible, especially if caught early before ARDS sets in (that’s great news!)
• Infants who experience oxygen toxicity may have reduced lung function and be prone to respiratory infections throughout life
• Infants with retinopathy of prematurity may experience resolution of symptoms, though late-stage retinopathy can significantly damage the eye and can even lead to loss of vision

So, there you have it…your quick guide to oxygen toxicity. If you take nothing else from this lesson, let it be this: oxygen is considered a medication and must be administered as carefully as you would any other pharmacological agent. And, next time you’re at the bedside, take a look at your patient and their FiO2 and ask yourself, “Could this patient be on less oxygen?” If the answer is yes, begin weaning and know you’re doing a great job helping your patient avoid a potential complication. Go you!

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References:

Budavari, A. I., Hartsell, Z., Glenn, T. J., Wesselius, L., & Wilkens, J. (2007). Oxygen‐induced Pulmonary Toxicity 20 Years After Bleomycin Exposure. Journal of Hospital Medicine, 2(2). https://shmabstracts.mystagingwebsite.com/abstract/oxygeninduced-pulmonary-toxicity-20-years-after-bleomycin-exposure/

Cooper, J. S., Phuyal, P., & Shah, N. (2025). Oxygen Toxicity. In StatPearls. StatPearls Publishing. http://www.ncbi.nlm.nih.gov/books/NBK430743/

Davies, S. P., & Carruthers, H. (2013). Adult spontaneous and conventional mechanical ventilation. In Tidy’s Physiotherapy (Fifteenth, pp. 129–145). Churchill Livingstone. https://www.sciencedirect.com/science/article/abs/pii/B9780702043444000079

Lius, E. E., & Syafaah, I. (2022). Hyperoxia in the management of respiratory failure: A literature review. Annals of Medicine and Surgery, 81, 104393. https://doi.org/10.1016/j.amsu.2022.104393

MD Searchlight Team. (2024, July 30). Oxygen Toxicity. MD Searchlight. https://mdsearchlight.com/health/oxygen-toxicity/

National Eye Institute. (2025). Retinopathy of Prematurity. National Eye Institute. https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/retinopathy-prematurity

Oxygen Toxicity. (n.d.). Science Direct. https://www.sciencedirect.com/topics/nursing-and-health-professions/oxygen-toxicity

Singer, M., Young, P. J., Laffey, J. G., Asfar, P., Taccone, F. S., Skrifvars, M. B., Meyhoff, C. S., & Radermacher, P. (2021). Dangers of hyperoxia. Critical Care, 25, 440. https://doi.org/10.1186/s13054-021-03815-y

Last Updated on January 6, 2026 by Maureen Osuna, MSN, RN