Hyperbaric Oxygen Therapy Side Effects


Hyperbaric oxygen therapy (HBOT) is breathing 100% oxygen while under raised atmospheric pressure. The term ‘hyperbaric’ refers to an increased atmospheric pressure.

The patients sit in a chamber that provides high pressure oxygen which helps to increase absorption of the oxygen in the body tissues. This experience in the chamber is called a ‘dive’. High concentrations of oxygen promotes healing and reduces infections. Hyperbaric oxygen therapy is generally used in conjuction with other treatment modalities.1,2

In this article we will discuss the side effects of HBOT.

Side effects


A more frequently seen side effect, barotrauma is damage to the tissues that is caused due to the high pressure of oxygen.1,2,3 It presents as the following:

  • Ear pain
  • Ear fullness
  • Muffled hearing (Reduced hearing)
  • Sinus pain
  • Sinus bleeding
  • Tooth pain
  • Dry cough
  • Chest pain
  • Chest burning sensation

The treatment for this complication varies according to the site of injury.1,2,3 Your healthcare provider can manage it with some of the following ways:

  • Placement of tympanoplasty tubes (Also known as grommets.)
  • Autoinflation techniques (forced opening of the Eustachian tubes by raised intranasal pressure)
  • Pseudoephedrine/oxymetazoline (nasal decongestants)
  • Anti histamines
  • Nasal steroid sprays (used to decrease swelling and inflammation)
  • Increased decompression time
  • No breath holding during the procedure
  • Thoracostomy (placement of a chest tube)

Round or oval window blowout

The ear has a round and an oval window. There are two openings present in the ear that help in the conduction of sound.1,3,4 High pressured air can damage these windows, even break them. The symptoms of round or oval window blowout are:

  • Sudden deafness
  • Tinnitus (ringing sound in the ear)
  • Vertigo (loss of balance)
  • Nystagmus (rapid involuntary eye movements)
  • Nausea
  • Dizziness

It can be treated by an Ear, Nose and Throat specialist and it may require surgical intervention in some cases.3,4

Oxygen toxicity

High dose oxygen causes oxygen toxicity which affects the central nervous system (the brain and the spinal cord) and hence it causes the following:

  • Seizures (uncommon)
  • Dizziness
  • Headache
  • Fever

All the symptoms are treated accordingly.1,3,4 The oxygen is reduced from the source and the treatment intervals are shortened. Medications aren’t required unless the condition becomes severe.5

Visual changes

If there is trauma to the eye, the lens morphology can be changed. This can cause myopia (short-sightedness). In most cases it resolves spontaneously after the procedure is finished.

In some cases, cataracts occur (clouding in the lens), this can result in hazy vision. To prevent this patients are screened for cataracts before the procedure.1,3,4


In the lungs, high pressure oxygen can cause pneumothorax. This occurs when air enters the cavity between the lung and the chest wall, resulting in a collapsed lung. An emergency medical team is present in case this occurs, the lung will be decompressed by placement of an intercostal drain and therapy stopped.6 HBOT can also cause other types of lung damage such as fluid in the lungs, lung failure, etc. 

These injuries can present as:

  • Difficulty in breathing
  • Pain in breathing
  • Chest pain
  • Nausea1,3,4


Being present in a small space for a prolonged period of time can trigger claustrophobia in some people, which is the fear of confined spaces.1,3,4 This can cause anxiety or panic attacks. The medical team is well prepared if such a scenario occurs. In some cases a mild sedative is given to calm the patient before the therapy.7

Other side effects

Some other side effects include:

  • Fatigue
  • Middle ear infections: Generally treated using antibiotics.
  • Ear bleeding
  • Allergic reaction to the mask: Generally treated using an epi-pen or further medications.
  • Increased blood pressure: In most cases it resolves after the treatment is completed.
  • Hypoglycemia (reduced blood glucose)1,3,4

These are treated symptomatically. Diabetic patients are advised to eat before the therapy to reduce the chances of hypoglycemia.1,3

Precautions and safety measures

Before HBOT, precautions can be taken to prevent side effects. The healthcare provider specifies these in detail before the procedure.1,3,4,7

  • It should not be used in people with recent eye or ear surgeries or injuries
  • It should not be used during a cold or a fever
  • It should not be used in certain lung diseases
  • Patients are advised to stay hydrated
  • Proper Screening should be done before HBOT
  • Monitoring of vitals during sessions is of utmost importance
  • The patient is advised to report any side effects during and after the procedure
  • An individualised approach can reduce the overall risk of the procedure


Hyperbaric oxygen therapy (HBOT) involves breathing 100% oxygen under elevated atmospheric pressure, typically administered in a chamber. This treatment, utilised alongside other therapeutic approaches, aims to enhance oxygen absorption in body tissues, promoting healing and reducing infections. However, it is essential to consider the potential side effects associated with HBOT. 

Barotrauma, a common side effect, manifests as ear and sinus discomfort, tooth pain, dry cough, and chest sensations. Treatment options vary, including techniques like tympanoplasty tubes and medications. 

Another complication, known as round or oval window blowout, involves damage to the ear's windows, causing symptoms like sudden deafness and vertigo, often requiring specialist intervention.

Oxygen toxicity, affecting the central nervous system, may lead to seizures and visual changes, but adjustments in oxygen levels and treatment intervals can address these issues. HBOT can also pose risks to the lungs, potentially causing pneumothorax or other lung-related problems. 

Claustrophobia, anxiety, and panic attacks may arise due to the confined space of the chamber, managed with medical preparedness or mild sedatives. 

Additional side effects include fatigue, ear infections, bleeding, allergic reactions, increased blood pressure, and hypoglycemia. These are addressed symptomatically.

Precautions are outlined before therapy, e.g. such as avoiding iHBOT in certain medical conditions or history of recent surgical procedure. 

Monitoring of vitals during sessions, proper hydration, and individualised approaches contribute to minimising risks and ensuring the safety of HBOT procedures. It is crucial for patients to communicate any side effects promptly to healthcare providers for appropriate intervention.


Can I eat before an HBOT session?

Eating a light meal before a session is generally acceptable, but specific guidelines may vary and should be discussed with healthcare providers.

Is HBOT painful?

The procedure is generally painless. Patients may experience discomfort due to pressure changes, but this is usually well-tolerated. Patients are advised to report any unforeseen discomfort to the doctor during the procedure.

How long does an HBOT session last?

Session durations vary but typically last between 60 to 90 minutes. Normally it is less than 2 hours.

How many sessions are needed?

The number of sessions depends on the condition being treated. Some conditions may require multiple sessions over weeks, others may require less.


  1. Hyperbaric oxygen therapy: overview, hyperbaric physics and physiology, contraindications. [Internet] 2021 [cited 2024 Jan 25]; Available from: https://emedicine.medscape.com/article/1464149-overview
  2. Heyboer M, Sharma D, Santiago W, McCulloch N. Hyperbaric oxygen therapy: side effects defined and quantified. Adv Wound Care (New Rochelle). [Internet] 2017 [cited 2024 Jan 25];6(6):210–24. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5467109/
  3. Johns Hopkins Medicine. Hyperbaric oxygen therapy. [Internet] 2022 [cited 2024 Jan 25]. Available from: https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/hyperbaric-oxygen-therapy
  4. Cleveland Clinic. Hyperbaric oxygen therapy: what it is & benefits, side effects [Internet] [updated 2023 Jan 7; cited 2024 Jan 25].. Available from: https://my.clevelandclinic.org/health/treatments/17811-hyperbaric-oxygen-therapy
  5. Ortega MA, Fraile-Martinez O, García-Montero C, Callejón-Peláez E, Sáez MA, Álvarez-Mon MA, et al. A general overview on the hyperbaric oxygen therapy: applications, mechanisms and translational opportunities. Medicina (Kaunas). [Internet] 2021 [cited 2024 Jan 25];57(9):864. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8465921/
  6. U.S. Food and Drug Administration.  Hyperbaric oxygen therapy: get the facts. FDA [Internet].  Jul 26 [update 2021 July 26; cited 2024 Jan 25]; Available from: https://www.fda.gov/consumers/consumer-updates/hyperbaric-oxygen-therapy-get-facts
  7. [Internet]. [ cited 2024 Jan 25]. Editor(s): Geoffrey J. Laurent, Shapiro SD, editors Hyperbaric Oxygen Therapy. [Internet] Encyclopedia of Respiratory Medicine. Academic Press. 2006 [cited 2024 Jan 25] 292-296. Available from: https://www.sciencedirect.com/topics/medicine-and-dentistry/hyperbaric-medicine#chapters-articles
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Meenakshi Khatri

Bachelor of Medicine, Bachelor of Surgery (M.B.B.S)

Dr. Meenakshi blends her clinical practice with scholarly pursuits. She works as a clinical assistant (junior doctor) in a cardiology practice in India. She actively contributes to medical knowledge and recently authored a chapter on antioxidants in a book publication. Her goal is to focus on both practical patient care and advancing medical understanding.

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