What happens in an HBOT session?

The unfamiliar part of an HBOT session is the change in pressure. Once the chamber reaches its operating pressure, the hour is usually quiet: you lie down, breathe through the oxygen system and remain in contact with the operator.

Here is the process without the promotional gloss.

Before you travel

No referral needed. Medical consultation included with every Course. For a course, one consent and medical declaration is associated with session one and sent around 24 hours beforehand.

Reception handles routine completion and risk agreement. A flagged answer is referred for clinical review before treatment proceeds. That exception pathway is important, but it is not imposed on every patient.

Do not attend with urgent symptoms in place of seeking urgent medical care. If you have a cold, blocked sinuses or new ear symptoms, contact the centre because pressure equalisation may be difficult.

How should you prepare for your first session?

A little preparation makes the first hour calmer.

• Read the declaration carefully. Answer every question honestly, including medicines, recent illness, ear or chest problems and pregnancy. Our guide to who HBOT is not suitable for explains why each question matters.
• Travel light. Anything that cannot go into the chamber has to be left outside, so bring only what you need.
• Plan the time. Allow extra time for changing and the briefing on a first visit, and avoid rushing straight into a demanding meeting afterwards until you know how you respond.
• Mention worries early. If enclosed spaces or ear pressure concern you, tell reception before the day so the process can be explained in advance.

Arriving and changing

You change into approved cotton clothing and leave prohibited items outside. Lighters, vapes, battery devices and products that increase fire risk are not taken into the chamber.

These are safety controls for an oxygen-enriched treatment environment. They are not preferences and may feel stricter than an ordinary wellness appointment.

The briefing

Before pressurisation, the operator explains:

1. how to equalise your ears;
2. how to communicate during the session; and
3. how the session is stopped if you want it stopped.

Ask questions before the chamber closes. Understanding the sequence makes the pressure change much less surprising.

What happens as the chamber pressurises?

The chamber pressurises gradually. Your ears may feel full as the pressure changes, much like an aircraft descent. The tube that links the middle ear to the back of the nose normally opens when you swallow, yawn or chew, which lets pressure on both sides of the eardrum equalise. NHS guidance on Eustachian tube problems describes the same swallowing, yawning and chewing techniques for flying.

Never force through significant pain. Tell the operator, who can pause or slow the pressure change. Ear and sinus discomfort are among the most common problems associated with HBOT.

At pressure

The centre’s chamber operates at 1.5 ATA. You breathe through the supplied oxygen system and can communicate with the operator throughout.

Many people read, listen to something or sleep. Electronics and permitted activities follow the centre’s chamber-safety rules, so check before bringing anything with you.

If your ears start to feel full again while you are at pressure, keep swallowing or yawning gently and tell the operator if it does not settle. It is also fine to say you feel warm, cold, restless or uneasy. Those are ordinary things to mention, and the operator would rather hear them early than have you sit through the hour uncomfortable.

The chamber is single occupancy: one patient per session. “Doctor-led” does not mean a doctor sits beside the chamber continuously; it describes the clinical governance and escalation setting. The operator remains responsible for the active session.

Decompression and leaving

Pressure returns to normal gradually. You may notice your ears again. Once decompression is complete, you change and leave.

Most people resume ordinary activities, but individual responses vary. Tell staff if you feel unwell, notice significant ear pain or have a visual change. Do not drive unless you feel safe to do so.

What might you notice after a course of sessions?

Most people notice nothing beyond ear pressure during the change in pressure. Over a longer course, two effects are worth knowing about. A 2023 Cochrane review of hyperbaric trials, mostly at higher pressures than ours, recorded ear barotrauma and a temporary reduction in visual sharpness as the main adverse effects. If distance vision blurs, stop driving until it clears and tell the centre.

Report ear pain that does not settle, a change in hearing, or feeling unwell after a session. Chest pain or severe breathlessness needs urgent help: call 999.

What HBOT does not feel like

It is not an operation, infusion or sedation. You remain awake and able to communicate. It should not involve enduring severe ear pain, being unable to reach the operator or feeling pressured to continue.

Claustrophobia varies. If enclosed spaces concern you, contact reception before attending so you understand the chamber and available options. Every Course includes a doctor consultation, while routine booking remains direct.

Before choosing a course

Read the evidence page relevant to your goal. HBOT is not proven for every condition, and results from one pressure or schedule cannot automatically be transferred to another. Our explainer on what hyperbaric oxygen therapy is sets out where the evidence is established.

Then review the session frequency guide, choose your preferred first visit and inspect every proposed date before checkout. The full treatment walkthrough is on what happens during treatment, and current options are on the pricing page.