A typical HBOT session lasts 60–90 minutes at pressure, with total clinic time of 1.5–2 hours. Most patients describe the experience as more relaxing than expected once they know what to expect during each phase. This guide covers everything from arrival to post-session, including what you will feel, hear, and experience during compression, treatment, and decompression.
Before You Arrive: Preparation
The night before your first HBOT session, shower and avoid applying petroleum-based products. These are prohibited in the chamber because they become flammable in the oxygen-enriched environment. Wear comfortable, loose clothing to the facility. You will change into approved cotton garments provided by the facility.
Eat a light meal 1–2 hours before your session. Avoid arriving on an empty stomach or immediately after a large meal. Stay well hydrated. If you are diabetic, check your blood glucose before the session; hypoglycemia is a known (though uncommon) side effect of HBOT.
Arrive 15–20 minutes early for your first session to allow time for intake, safety review, and getting comfortable with the environment before entering the chamber.
What You Cannot Bring Into the Chamber
Before compression, you will be screened for prohibited items:
- All electronics: smartphones, smartwatches, hearing aids (unless specifically approved), Bluetooth headphones
- Synthetic fabrics: change into the facility’s approved 100% cotton garments
- Personal care products: no deodorant, perfume, makeup, sunscreen, lip balm, or petroleum-based products
- Hard contact lenses: remove before entering; soft lenses are generally permitted
These prohibitions exist because the enriched oxygen environment makes these items fire hazards. A facility that does not enforce intake screening is not operating safely.
Compression Phase (10–15 Minutes)
You will lie on a padded gurney (in a monoplace chamber) or sit in a chair or on a bench (in a multiplace chamber). The chamber is sealed and compression begins.
What you will feel: Gradual ear pressure or fullness, similar to the sensation during airplane descent or diving into a pool. Some patients also notice mild warmth as pressure increases. This is normal and temporary.
Equalization techniques: Your provider will teach these before your first session. Use them during compression:
- Swallow
- Yawn
- Valsalva maneuver: pinch your nose and blow gently (as if trying to clear your ears)
If you cannot equalize: Alert the technician via intercom immediately. They can pause compression briefly while you equalize. Do not suffer through pain. Ear pain that is not addressed can progress to barotrauma.
Middle ear barotrauma (ear pressure injury) affects approximately 9–15% of patients, but most cases are mild and self-resolving when patients communicate problems promptly.[2]
Treatment Phase (60–90 Minutes)
Once the chamber reaches operating pressure, the treatment phase begins. You breathe normally. You do not need to do anything special with your breathing; the elevated oxygen concentration does the work automatically.
Common experiences during treatment:
- Warmth that gradually fades as you acclimate to the pressure
- Mild tingling, especially in the first few sessions
- Deep relaxation; many patients nap
- Heightened sense of energy in some patients
- Possibility of slight visual changes (temporary myopia is common with extended treatment courses)
You can communicate with staff outside via intercom throughout the session. In monoplace chambers, staff remain nearby and observe you continuously through the acrylic viewport. In multiplace chambers, trained staff are inside the chamber with you.
Air breaks (5 minutes breathing room air via mask while remaining at pressure) are standard practice at many facilities every 25–30 minutes. This reduces oxygen toxicity risk significantly: air breaks cut seizure frequency from 3.9 to 1.2 per 10,000 sessions without reducing therapeutic benefit.[4]
Decompression Phase (10–15 Minutes)
At the end of treatment, pressure is gradually reduced to normal atmospheric levels. You may feel ear pressure again during decompression, though most patients find it less noticeable than compression. Use the same equalization techniques. Decompression typically takes 10–15 minutes.
After Your Session
Most patients feel relaxed, some feel energized, and many report reduced pain or improved mental clarity in the hours following HBOT. You can resume normal activities immediately. No recovery period is required.
Stay hydrated. HBOT can affect glucose levels in diabetic patients; check your blood glucose after the session if you are on insulin or glucose-lowering medications.
If you experience ear pain or muffled hearing after the session, inform your provider. Most post-session ear discomfort resolves within hours. Persistent or worsening ear pain warrants medical evaluation.
How Many Sessions Will You Need?
Treatment course length depends on the condition being treated:[3]
| Condition Type | Average Sessions | Typical Schedule |
|---|---|---|
| Acute injuries (fasciitis, gangrene) | ~15 sessions | 5 days/week |
| Chronic conditions (osteomyelitis, diabetic ulcers) | ~30 sessions | 5 days/week |
| Radiation injury | 30–40 sessions | 5 days/week |
| TBI, neurological (off-label) | 40–60 sessions | 5 days/week |
| General wellness (off-label) | 20–40 sessions | Varies |
What to Tell Your Provider Before Starting
- Any current medications, especially chemotherapy (bleomycin, cisplatin, doxorubicin, disulfiram have interactions with HBOT)
- History of ear problems, previous ear surgery, or chronic congestion
- History of pneumothorax or lung conditions
- Diabetes and current glucose management approach
- Anxiety or claustrophobia (so the team can prepare appropriate support)
- Pregnancy (HBOT safety in pregnancy is not established)
- Recent upper respiratory infection
Frequently Asked Questions
Does HBOT hurt?
For most patients, no. The main discomfort is ear pressure during compression, which is manageable with proper equalization technique. Patients who communicate immediately when they feel ear pain and use equalization techniques rarely experience more than mild temporary discomfort.
Can I drive home after HBOT?
Most patients can. HBOT does not cause sedation or impaired judgment. Some patients feel drowsy from relaxation during the session; if you feel unusually tired after your first session, arrange for a ride until you know how you respond. Over time, most patients feel energized rather than drowsy after sessions.
What if I need to stop the session?
Tell the technician via intercom. They will begin controlled decompression. You cannot exit the chamber while it is pressurized; decompression takes 10–15 minutes for safety. This is why communicating discomfort early, rather than waiting, matters. Early communication allows problems to be managed before they require stopping the session entirely.
References
- Dias MD, Fontes B, Poggetti R, Birolini D. HBOT: types of injury and number of sessions. Undersea & Hyperbaric Medicine. 2008;35(4):259-268. PMID: 18351127
- Voigt A, et al. Systematic Review of Otologic Adverse Events in HBOT. Undersea & Hyperbaric Medicine. 2025. DOI: 10.22462/736. PMID: 41429031
- Dias MD, et al. HBOT types of injury and number of sessions. 2008. PMID: 18351127
- Costa DA, et al. Seizure frequency in more than 180,000 HBOT sessions. Diving and Hyperbaric Medicine. 2019;49(3). DOI: 10.28920/dhm49.3.167-174. PMID: 31523791
- Macinnes L, et al. Patient knowledge and experience of HBOT. Diving and Hyperbaric Medicine. 2021;51(1):72-77. PMID: 33761544
- Cleveland Clinic. Hyperbaric Oxygen Therapy. my.clevelandclinic.org
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.
