Overall Safety Profile
In a retrospective analysis of 1.5 million hyperbaric treatments, only 0.68% were associated with any adverse event, and medically severe events occurred in fewer than 1 in 10,000 sessions. HBOT has one of the lowest serious adverse event rates of any medical intervention in widespread clinical use. Most side effects are mild ear pressure or sinus discomfort that resolves on its own.
What Are the Side Effects and Risks?
| Side Effect | Incidence | Severity | Resolution |
|---|---|---|---|
| Middle ear barotrauma | 3.8-15% of patients24 | Mild-moderate | Self-resolving; PE tubes if recurrent |
| Ear pain/discomfort (transient) | 17%+ of patients5 | Mild | Equalization training; resolves spontaneously |
| Sinus barotrauma | 0.58% of patients6 | Mild | Decongestants; resolves with treatment |
| Claustrophobia/anxiety | 0.5-2% of patients2 | Mild-moderate | Sedation, acclimation, or switch to multiplace |
| Oxygen toxicity (CNS seizure) | <0.05 per 1,000 treatments1 | Serious (self-limiting) | Remove mask; seizure stops within minutes |
| Pulmonary barotrauma (pneumothorax) | 1 case in 1,529,859 treatments1 | Serious | Requires immediate medical management |
“In a retrospective analysis of 1.5 million hyperbaric treatments, only 0.68% were associated with any adverse event, and medically severe events occurred in fewer than 0.05 per 1,000 treatments.”
Jokinen-Gordon et al. 2017, Advances in Skin & Wound Care
Barotrauma: The Most Common Issue
Barotrauma occurs when pressure changes during compression or decompression cause tissue injury to air-filled spaces. The middle ear is most commonly affected because the Eustachian tube must actively equalize pressure between the middle ear and the chamber environment.
A 2025 systematic review of 54 studies involving 18,284 patients found that 15% of HBOT patients experienced otologic (ear-related) complications.4 Of these cases, 42.8% were classified as mild.
Middle Ear Barotrauma Severity
| Severity | Percentage of Cases |
|---|---|
| Mild | 42.8%4 |
| Moderate | ~50.8%4 |
| Severe | 6.4%4 |
What Are the Side Effects and Risks?
A 2023 meta-analysis of 24 RCTs found that adverse events were significantly more common when chamber pressure exceeded 2.0 ATA or when treatment courses exceeded 10 sessions.3 Female sex, age under 16, increasing age, head and neck pathology, and sensory neuropathy also increase barotrauma risk.24
Oxygen Toxicity Seizures
“Only one confirmed case of pneumothorax was documented across 1,529,859 HBOT treatments over four years. Oxygen toxicity seizures occurred in fewer than 0.05 per 1,000 treatments.”
Jokinen-Gordon et al. 2017, Advances in Skin & Wound Care
Key facts about HBOT oxygen toxicity seizures:12
- Incidence: Fewer than 0.05 per 1,000 treatments at 2.0-2.4 ATA
- Self-limiting: Removing the oxygen mask stops the seizure within minutes
- No lasting damage: HBOT oxygen toxicity seizures do not cause lasting neurological injury
- Prevention: Air breaks (5 minutes breathing room air every 20-30 minutes) significantly reduce risk
Safety Comparison with Other Medical Procedures
| Procedure | Serious Adverse Event Rate | Source |
|---|---|---|
| HBOT (any AE) | 0.68% per session | Jokinen-Gordon 2017 |
| HBOT (oxygen toxicity) | 0.005% per session | Jokinen-Gordon 2017 |
| Colonoscopy (perforation) | 0.01-0.3% | ASGE guidelines |
| General anesthesia mortality | 0.01-0.02% | ASA data |
Chamber-Specific Safety
Clinical Hard Chambers
Clinical hard chambers at hospitals and accredited facilities have the strongest safety record, with trained technicians, emergency protocols, and fire suppression systems. The oxygen-enriched environment requires strict prohibition of flammable items inside the chamber.
Home Soft Chambers
Home soft chambers operating at 1.3 ATA have lower barotrauma and oxygen toxicity risk due to lower pressure, but unsupervised use removes the clinical safety net. Key risks include improper equalization technique and fire hazard from oxygen concentrators.
Absolute Contraindications
- Untreated pneumothorax (collapsed lung)
- Certain chemotherapy agents (doxorubicin, bleomycin, cisplatin)
- Uncontrolled high fever
- Active seizure disorder (relative contraindication at higher pressures)
- Jokinen-Gordon H, Barry R, Watson B, Covington DS. (2017). A retrospective analysis of adverse events in HBO therapy (2012-2015): Lessons learned from 1.5 million treatments. Advances in Skin & Wound Care. DOI: 10.1097/01.ASW.0000508712.86959.c9. PMID: 28198743.
- Hadanny A, Meir O, Bechor Y et al. (2016). The safety of hyperbaric oxygen treatment: retrospective analysis in 2,334 patients. Undersea & Hyperbaric Medicine. PMID: 27265988.
- Zhang Y, Zhou Y, Jia Y et al. (2023). Adverse effects of hyperbaric oxygen therapy: A systematic review and meta-analysis of 24 RCTs. Frontiers in Medicine. DOI: 10.3389/fmed.2023.1160774.
- Voigt A, Laspro M, Thys E et al. (2025). Systematic review of otologic adverse events in HBO therapy (54 studies, 18,284 patients). Undersea & Hyperbaric Medicine. DOI: 10.22462/736.
- Plafki C, Peters P, Almeling M et al. (2000). Complications and side effects of hyperbaric oxygen therapy. Aviation Space & Environmental Medicine. PMID: 10685584.
- Hung CW et al. (2003). Hyperbaric oxygen therapy is safe: Mid-Taiwan experience.
- Mirasogl B, Cakkalkurt A, Cimsit M. (2017). Complication of HBOT: Symptomatic middle ear and cranial sinus barotrauma. DOI: 10.18017/IUITFD.308489.
- FDA. Hyperbaric Oxygen Therapy: Don’t Be Misled. Consumer safety communication. fda.gov
Medical Disclaimer
The content on BaricBoost.com is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
Author
Seph Fontane Pennock is the founder of BaricBoost.com and Regenerated.com, a clinic directory for regenerative medicine serving 10,000+ providers across the United States. He previously built and sold PositivePsychology.com, which grew to 19 million users and became the largest evidence-based positive psychology resource on the web. Seph brings direct experience as an HBOT patient, having completed protocols at clinics across three continents while navigating mold illness, systemic inflammation, and autoimmune conditions. His treatment journey includes hyperbaric oxygen therapy, peptide protocols, NAD+ therapy, and consultations with specialists from Dubai to Cape Town to Mexico. This combination of entrepreneurial track record and lived patient experience shapes everything published on BaricBoost.com. Every article is grounded in peer-reviewed research, informed by real clinical encounters, and written for patients making high-stakes treatment decisions. Seph's focus is on bringing transparency, scientific rigor, and practical guidance to the hyperbaric oxygen therapy space.
