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Some physicians and scientists suggest that administering chemotherapy, immunotherapy, or radiotherapy at a specific time of day can improve response to treatment. 

Safety and precautions

Side effects or adverse events

Because oxygen is a radiosensitizer, HBOT can increase the risk of injury for people undergoing radiation therapy.1Bennett MH, Feldmeier J et al. Hyperbaric oxygenation for tumour sensitisation to radiotherapy. Cochrane Database of Systematic Reviews. 2018 Apr 11;4(4):CD005007. High levels of oxygen can also cause neurological problems (oxygen toxicity), including seizures.2Bennett MH, Feldmeier J et al. Hyperbaric oxygenation for tumour sensitisation to radiotherapy. Cochrane Database of Systematic Reviews. 2018 Apr 11;4(4):CD005007; Ward AJ, Stubbs B, Dixon B. Carcinoma of the cervix: establishment of a hyperbaric oxygen trial associated with the use of the cathetron. British Journal of Radiology. 1974 Jun;47(558):319-25.

HBOT can affect the ears (due both to pressure changes and oxygen toxicity to the nervous system) and the eyes; in one study, nearly half of all patients receiving HBOT had short-term vision or hearing loss.3Oscarsson N, Müller B et al. Radiation-induced cystitis treated with hyperbaric oxygen therapy (RICH-ART): a randomised, controlled, phase 2-3 trial. Lancet Oncology. 2019 Nov;20(11):1602-1614. In the long term, HBOT can also cause or worsen cataracts.4Bennett MH, Cooper JS. Hyperbaric Oxygen Therapy and Associated Cataracts. [Updated 2024 Jan 9]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-.

Finally, HBOT is dangerous for people with chest injuries or lung diseases such as COPD or emphysema, because if there is any air trapped in the chest, the pressure difference that HBOT creates can lead to a pneumothorax (lung collapse).5Gawdi R, Yrastorza J, Cooper JS. Hyperbaric Oxygen Therapy Contraindications. [Updated 2025 May 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. 

Interactions with other therapies

Some studies find that HBOT can increase the risk of radiation injury, though in some cases, it may also make radiation more effective.

Do not use (contraindications)

HBOT should not be used by people with chest injuries or illnesses that can trap air in the lungs, like COPD.

Keep reading about timing of therapies

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See all our reviews of complementary therapies

Author

Sophie Kakarala

Research Assistant
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Sophie received her Bachelor of Arts from the University of Cambridge, where she studied Middle Eastern languages and the philosophy of science. She then completed a premedical post-baccalaureate at the City University of New York. Before joining CancerChoices, she worked for several years at the Cornell Center for Research on End-of-Life Care, where she helped to conduct research on terminal illness and grief. Working in end-of-life research filled her with the conviction that all patients deserve free, accessible, and scientifically accurate information about the therapies available to them. While taking classes in anthropology, she also became curious about traditional medical knowledge and philosophies. These interests led her to CancerChoices. She is delighted to be part of CancerChoices’s work creating rigorous, evidence-based treatment guides for patients and physicians.

Sophie Kakarala Research Assistant

Nancy Hepp, MS

past Lead Researcher
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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS past Lead Researcher

Reviewer

Last update: December 19, 2025

Last full literature review: March 2025

CancerChoices provides information about integrative in cancer care, a patient-centered approach combining the best of conventional care, self care and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocial therapy, and acupuncture therapies and self-care lifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.

Our staff have no financial conflicts of interest to declare. We receive no funds from any manufacturers or retailers gaining financial profit by promoting or discouraging therapies mentioned on this site.

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