Safety & Contraindications

Absolute Contraindications

Conditions where HBOT must not be administered regardless of setting or pressure. Conditions where you should not use HBOT at all.

  • Untreated pneumothorax. Pressurization can convert a simple pneumothorax to tension pneumothorax during depressurization—a life-threatening emergency.
  • Untreated intraocular gas. Post-surgical SF6 or C3F8 gas expands under pressure changes, risking retinal detachment or permanent vision loss. Wait 3–6 months post-surgery for full gas resorption.
  • Certain chemotherapy agents. Bleomycin causes fatal pulmonary toxicity potentiated by hyperoxia. Doxorubicin increases cardiotoxicity risk. Cisplatin and Disulfiram (which blocks superoxide dismutase) are also contraindicated. Get oncologist clearance before combining HBOT with any active or recent chemotherapy.
  • Collapsed lung (pneumothorax). Pressure changes in the chamber can make a collapsed lung much worse. Must be treated first.
  • Recent eye surgery with gas bubble. Some eye surgeries leave a gas bubble inside the eye that expands dangerously under pressure. Wait 3–6 months for it to absorb.
  • Certain chemo drugs. Some chemotherapy drugs (especially Bleomycin, Doxorubicin, and Cisplatin) interact badly with high oxygen. Get your oncologist's clearance.

Relative Contraindications

These require evaluation, not automatic exclusion. Many patients with these conditions use HBOT safely with appropriate monitoring. These need a conversation with your doctor, but they don't automatically rule you out.

  • Active upper respiratory infection or sinusitis. Mucosal swelling impairs equalization, increasing barotrauma risk. Delay until resolved.
  • Seizure disorders. Oxygen lowers seizure threshold. Incidence at clinical pressure: ~1 in 634 treatments. At 1.5 ATA the risk drops substantially—ppO2 is roughly half that of clinical protocols.
  • COPD or emphysema. Bullae rupture risk under pressure changes. Imaging review recommended.
  • Pregnancy. Insufficient human data to establish safety. Animal studies haven't shown harm, but no one runs RCTs on pregnant women.
  • Implanted devices. Pacemakers, cochlear implants, and similar devices have pressure ratings. Most modern devices are rated well above 1.5 ATA. Check with manufacturer.
  • Severe claustrophobia. Manageable in many cases—soft chambers are see-through and can be unzipped from the inside. Anxiolytics used in clinical settings.
  • Cold or sinus infection. Congestion makes it hard to equalize ear pressure. Wait until you're over it.
  • Seizure disorders. High oxygen can lower the seizure threshold. The risk is low at home pressure (~1 in 634 at clinical pressure, much lower at 1.5 ATA).
  • COPD or emphysema. Weakened lung tissue can be stressed by pressure changes. Get imaging reviewed first.
  • Pregnancy. Not enough human data. Probably fine, but no one's proven it.
  • Implanted devices. Pacemakers, cochlear implants, etc. Most modern ones handle 1.5 ATA easily. Check the manufacturer rating.
  • Severe claustrophobia. Soft chambers are see-through and unzip from the inside. Most people adapt within a few sessions.

Common Side Effects

Side EffectFrequencyDetails
Ear barotrauma ~50% of users report it at some point; ~2% of individual treatments Middle ear barotrauma from Eustachian tube dysfunction during pressurization. Improves as equalization technique develops. Rare at 1.5 ATA vs. higher pressures. Ear pressure or pain during pressurization, similar to flying. Gets easier with practice. Much milder at home pressure than clinical.
Claustrophobia ~25% report it initially Anxiety response to enclosed space. Soft chambers mitigate this—transparent walls, interior unzipping, lower perceived confinement. Most patients habituate within three to five sessions. Feeling closed in. Soft chambers are see-through and you can unzip from inside. Most people adapt within three to five sessions.
Temporary myopia Uncommon Lens refractive index change from prolonged hyperoxia exposure. Fully reversible within weeks of stopping treatment. More common in extended clinical protocols (>40 sessions at 2.0+ ATA). Mild nearsightedness that goes away within weeks after you stop. More common at clinical pressure than home.
Fatigue / brain fog Common early (sessions 1–35) Expected component of the healing response. Immune upregulation and inflammatory clearance are metabolically expensive. Resolves as adaptive processes outpace inflammatory load. Your body is doing repair work and that takes energy. Normal during the first month. Clears up as you turn the corner around session 35.

Home vs. Clinical Risk

RiskHome (1.3–1.5 ATA, concentrator)Clinical (2.0–3.0 ATA, 100% O2)
Fire Negligible. Chamber fills with normal air; concentrator delivers 93% O2 only through the mask. Ambient O2 in chamber stays near 21%. Negligible. The chamber is filled with normal air. Oxygen only goes through your mask. Real risk. Monoplace chambers flood with 100% O2. Everything becomes flammable. Strict protocols required. Real. The whole chamber fills with pure oxygen. Static electricity or electronics can ignite it.
O2 toxicity seizure Negligible. ppO2 ~1.4 atm with concentrator at 1.5 ATA. Well below the Paul Bert threshold (~1.7 atm for extended exposure). Negligible. The oxygen level at home pressure stays well below the seizure danger zone. Low but real. ppO2 2.0–3.0 atm. Incidence ~1 in 634 treatments. Self-limiting (tonic-clonic resolves when O2 removed). Low but real. About 1 in 634 treatments. Seizure stops when oxygen is removed.
Barotrauma Mild. Maximum 7 PSI (0.5 ATA gauge). Equivalent to 11 feet of seawater. Ear barotrauma possible; sinus/pulmonary extremely rare. Mild. 7 PSI max—like diving to 11 feet. Ear discomfort possible. Serious injury very rare. Higher. 15–30 PSI (1.0–2.0 ATA gauge). Ear, sinus, and pulmonary barotrauma all documented. Higher. 15–30 PSI. Ear, sinus, and lung barotrauma all documented.
Decompression None. Below the threshold for nitrogen supersaturation at any treatment duration. None. Home pressure is too low to cause decompression issues. Minimal above 2.0 ATA. Standard treatment durations stay within no-decompression limits, but protocol adherence matters. Minimal. Possible above 2.0 ATA with extended sessions, but clinical protocols manage this.
Pulmonary O2 toxicity Not at standard session lengths. Lorrain-Smith effect requires sustained high ppO2 beyond what concentrator-based protocols produce. Not a factor at standard session lengths with a concentrator. Possible with extended or repeated sessions. Tracked via UPTD (Unit Pulmonary Toxicity Dose). Air breaks mitigate accumulation. Possible with extended treatments. Managed with air breaks during sessions.

Zero reported deaths from home soft-shell chambers at 1.3–1.5 ATA with a concentrator. Every fatal HBOT incident on record involved clinical pressure, 100% O2 from tanks, or both.

References

Adverse Effects

Yan, L. et al. "Adverse effects of hyperbaric oxygen therapy: a systematic review and meta-analysis." Front Med, 2023.

Seizure Incidence

Hazzard, B. et al. Seizure incidence approximately 1 in 634 treatments. PLoS One, 2025.

Yildiz, S. et al. Seizure incidence in 80,679 patient-treatments. Aviat Space Environ Med, 2004.

Fire Safety

FDA Safety Communication regarding hyperbaric oxygen therapy fire hazards. August 2025.