Why You Can't Breathe Ozone: Risks and What to Do

Ozone gas must never be inhaled. The fluid lining the lungs has no antioxidants to buffer ozone, so inhaled ozone damages lung tissue. The Madrid Declaration on Ozone Therapy, 4th edition (ISCO3, 2025) does not recommend the inhalation route and lists breathing ozone gas as a contraindication [1]. Every ozone therapy method is built to keep the gas out of your lungs.

This page explains why, what to do after an accidental exposure, and how to prevent one at home. Check with your healthcare provider before starting, especially if you are pregnant, have a heart or bleeding condition, or take blood thinners.

Why can't you breathe ozone?

Blood and other body fluids are full of antioxidants. When a small, measured dose of ozone meets them, they react with it right away, which is the basis of ozone therapy (how ozone therapy works). The surface fluid in the deep lung (the alveoli) has none of that protection. The Declaration says that on inhalation, because of the complete absence of antioxidants in that fluid, ozone is completely toxic. It calls inhalation strictly prohibited and says the lungs are extremely sensitive to oxidative damage from ozone [1].

Ozone therapy supporters and critics agree on this point. The FDA's well-known "toxic gas" line is about breathing ozone. See the FDA "toxic gas" statement, explained.

What does breathing ozone do?

Ozone irritates and inflames the lining of the airways. Even smog-level ozone can cause coughing, throat irritation and chest tightness, as covered in the safety of ozone therapy. The FDA's rule adds that fluid can build up in the lungs (pulmonary edema) with onset delayed for some hours after exposure, so feeling fine right away is not a reliable sign. The Declaration says inhaling ozone causes very severe damage to the body [1]. It also calls sublingual ozone, which involves inhaling the gas, clearly inappropriate.

What should I do if I breathe ozone by accident?

At home:

1. Leave the room and get fresh air.
2. Open windows and doors so the room can ventilate before anyone goes back in.
3. Watch for coughing, chest tightness or shortness of breath. Seek medical care if they do not settle quickly, and call emergency services for serious trouble breathing. Symptoms can show up hours later.
4. Do not use ozone again until you know what went wrong, such as a leak, a missing destruct or a poorly ventilated room.

Note for practitioners. The Declaration's steps for accidental inhalation poisoning are, in short: evacuate the room and open windows and doors; monitor the person in another room (pulse oximetry, blood pressure, heart rate, respiratory rate and lung sounds to spot bronchospasm); make sure there is IV access; have IV vitamin C (1 to 2 g) and, depending on severity, IV glutathione (20 mg/kg) available; give oxygen by mask at 3 L/min until readings return to normal; and ventilate the room well. It recommends that all staff be certified in CPR. The full guidance is in the ISCO3 document "First Aid in Ozone Therapy" [1].

How do I prevent it at home?

• Use an ozone destruct so leftover ozone is destroyed instead of released.
• Ventilate. Use a well-ventilated room, and a fan for methods that release gas into the room, such as vaginal insufflation. Ozone escapes from ozone water as you drink it, and from ozone oil while you make it, so do both in a ventilated room and do not breathe in over the glass or flask.
• Keep tubing and fittings in good shape. Ozone breaks down tubing slowly, so replace it when it turns stiff, cloudy or cracked.
• Never sniff the gas to test it. The FDA's rule notes that the sense of smell tires quickly, so the odor is not a reliable guide to how much ozone is in the air.
• Use a setup built for your method. See what you need at home: a checklist.

What about breathing ozonated oil (BOO)?

BOO is a different thing from breathing ozone gas. In BOO the gas is bubbled through olive oil first, and the ozone reacts with the oil almost at once. What you breathe is oxygen carrying the oil's vapor, not ozone gas. Even so, no formal safety studies of BOO exist, so start low, follow the protocol, and stop if you get a cough, chest tightness or a headache. Our informal checks found no ozone gas after the oil, but those were not a published study. See breathing ozonated oil (BOO) and the BOO protocol.

The Madrid Declaration says to never inhale ozone itself. In its section on inhaling oil vapors, it describes only ozonized oil aerosols made by an ultrasonic vapor generator.

One small hospital trial in Istanbul gave 30 adults with COVID-19 either ozone plus standard care (15) or standard care only (15). The ozone was bubbled through olive oil in a glass reservoir, mixed with cold water vapor from a nebulizer and given by mask, three 10-minute sessions a day for 5 days. The ozone group had a shorter hospital stay (about 18.7 vs 21.2 days), more patients who tested PCR-negative at day 5 (93% vs 20%) and a larger drop in CRP, and the authors reported no side effects [2]. This was a low-level ozone-in-oil vapor given in a hospital with a prototype device from the generator maker, not breathing ozone gas straight from a generator, and not guidance for home use.

Frequently asked questions

Why can’t you breathe ozone?

The fluid lining the lungs has no antioxidants to buffer ozone, so inhaled ozone damages lung tissue. The Madrid Declaration calls inhalation strictly prohibited.

What should I do if I breathe ozone by accident?

Leave the room, get fresh air, open windows and doors, and ventilate. Seek medical care if you have a cough, chest tightness or shortness of breath that does not settle, because symptoms can be delayed by hours.

Is the smell of ozone a good warning?

No. The sense of smell tires quickly, so the odor is not a reliable guide to how much ozone is in the air. Use a destruct and ventilation instead of relying on smell.

Is breathing ozonated oil (BOO) the same as breathing ozone?

No. The gas is bubbled through oil first and reacts with it, so you breathe oxygen carrying oil vapor. BOO has not had formal safety studies, so follow the protocol and stop if you cough or feel chest tightness. See the BOO article for details.

Does ozone water release ozone into the room?

Some ozone escapes as you make and drink ozone water, so do it in a ventilated room and do not breathe in over the glass or flask.

Sources

1. ISCO3. Madrid Declaration on Ozone Therapy, 4th edition (ISCO3, 2025). Sections 2.1 to 2.6 and 16. isco3.org
2. Dengiz E, Özcan Ç, Güven Yİ, et al. Ozone gas applied through nebulization as adjuvant treatment for lung respiratory diseases due to COVID-19 infections: a prospective randomized trial. Medical Gas Research. 2021;12(2):55-59. PMID 34677153.