Can Breathing Too Much Oxygen Cause Oxygen Toxicity?

You may be familiar with the expression “too much of a good thing.” This warning can be applied to just about anything — including oxygen.

Humans can only survive a few minutes without oxygen, so how could something so crucial ever be toxic? 

The air we breathe contains about 21% oxygen. Higher concentrations are used in medical treatment. But even though higher concentrations can be life saving, they can also cause damage to your body. Breathing in high levels of oxygen can lead to a condition called “oxygen toxicity.”

Let’s take a closer look at oxygen toxicity and what happens when your body gets too much of a good thing. 

How can oxygen be dangerous?

Our cells need to process oxygen just like any other substance. This creates a product called “free radicals.” Low levels of free radicals aren’t dangerous. Your body can clear them out just like other waste products.

But when you breathe in higher oxygen concentrations, more free radicals are created. If your body can’t keep up, these free radicals can cause damage to your:

• Lungs

• Heart

• Kidneys

• Thyroid

• Brain

Premature infants can also develop retina damage if they breathe high oxygen concentrations. This damage can cause permanent vision loss. 

Breathing in higher oxygen concentrations can also lead to throat and trachea (windpipe) irritation and dryness. When these parts of your body become dry, they start to crack, which gives bacteria an opportunity to get into the tissues and cause infection. 

How does someone breathe in too much oxygen?

People can breathe in too much oxygen when they breathe from a pure oxygen source, like an oxygen tank. 

It’s not possible to get oxygen toxicity from breathing regular air. That’s because no matter how fast or hard you breathe, the concentration of oxygen in the air is always the same, which is about 21%. 

But in a medical setting, people can receive a wide range of oxygen concentrations — from 21% to 100%. In medical settings, oxygen treatment is given as:

• Supplemental oxygen: When people have trouble breathing, they get oxygen therapy through masks, cannulas, and other devices. The oxygen comes from a tank or a portable oxygen concentrator. In a hospital, the oxygen comes from a spigot in the wall which connects to a built-in system. Devices that attach to the oxygen source allow a healthcare provider to change the concentration of oxygen that someone receives. 

• Hyperbaric oxygen therapy: People receiving hyperbaric oxygen therapy are exposed to high concentrations of oxygen under pressure for short periods of time. This therapy is used to treat only specific medical conditions like carbon monoxide poisoning, crush injuries, and decompression sickness (“the bends”). 

Some people also use higher concentrations of oxygen in non-medical settings, like oxygen bars. 

What are the signs of oxygen toxicity?

Signs of oxygen toxicity include:

• Pain when taking a breath

• Coughing

• Shortness of breath

These are signs that a person is developing inflammation and damage in their lungs. The signs usually happen when oxygen concentrations are higher than 50% and can usually start within 24 hours. 

When someone is receiving hyperbaric oxygen, signs of oxygen toxicity include:

• Visual changes

• Ringing in the ears

• Dizziness

• Confusion

• Hiccups 

These symptoms usually start within a few hours and are more likely to happen when someone is receiving oxygen under higher pressures.

How do you avoid oxygen toxicity? 

The best way to avoid oxygen toxicity is only to use exactly as much oxygen as you need. 

Healthcare providers will make sure to use the lowest oxygen concentrations when treating medical conditions. They also give people frequent breaks during hyperbaric oxygen treatment. 

Some medications can also increase your risk of oxygen toxicity. Let your healthcare providers know if you are taking:

• Dexamethasone

• Synthroid

• Acetazolamide

If you use supplemental oxygen for non-medical reasons, it’s a good idea to keep track of oxygen concentrations and duration of use. This can help you avoid overexposure. 

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Written by:

Ronald W. Dworkin, MD, PhD

Ronald W. Dworkin, MD, is a board-certified anesthesiologist who has been practicing anesthesiology in a community hospital for 30 years. He has taught in the honors program at George Washington University for over 10 years and works as a senior fellow at the Hudson Institute.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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