What Does HBOT Feel Like? 10 Things First-Timers Always Ask
By OxyPlus - Newcastle's Specialist Hyperbaric Oxygen Therapy Clinic oxyplus.co.uk | Updated August 2026 | 6 min read
Most people who contact OxyPlus for the first time have done plenty of research on the science of hyperbaric oxygen therapy. They know about telomeres and mitochondria and cerebral blood flow. What they actually want to know is much simpler:
“What is it going to feel like when I get in?”
It is a completely reasonable thing to wonder. You are being sealed into a pressurised chamber and breathing pure oxygen. If you have never done it before, the imagination tends to fill the gap with something more dramatic than the reality.
Here is the reality, answered question by question - from the people who ask us these things every day at OxyPlus, our HBOT clinic in Newcastle.
1. Is it claustrophobic?
This is the question we hear most often - and for most people, the concern turns out to be much bigger than the experience.
Our clinical hard-shell chambers are not the narrow, coffin-like tubes that people sometimes picture. They are spacious enough to sit up in, lie down comfortably, and move around. People relax, sit, or lie comfortably in these chambers. Many of our clients read, listen to music or podcasts, watch something on a device, or simply rest.
That said, claustrophobia is real and we take it seriously. Claustrophobia or anxiety related to confinement in hyperbaric chambers is a potential complication. If you have concerns about enclosed spaces, the most important thing is to tell us before your session. We can take the pressurisation more slowly, keep communication open throughout, and make sure you feel in control of the experience. We also have a window and intercom so you are never isolated.
Almost everyone who worries about claustrophobia finds, after their first session, that it was not the issue they expected.
2. Will my ears hurt?
Your ears are likely to notice the pressure change - but "hurt" is the wrong word for most people.
Your ears may feel clogged or start to pop, similar to flying in an airplane or travelling through mountains. This happens during the compression phase - the first 10–15 minutes as pressure builds to the treatment level. It is the same sensation as descending in a plane, and the fix is the same: yawn, swallow, chew, or gently hold your nose and swallow.
You can relieve this pressure in your ears by yawning or taking a sip of water, holding your nose and swallowing. We walk every first-timer through exactly how to do this before the session begins. Once the pressure stabilises at the treatment level, the sensation goes away entirely and stays away for the rest of the session.
Middle ear barotrauma is one of the most common side effects of HBOT. It occurs when the pressure change is not adequately equalised - causing discomfort in the ear canal. The risk is minimised by clearing your ears regularly during compression, which we will coach you through. If you have a cold, active sinus infection, or blocked ears on the day of your appointment, let us know - we may recommend rescheduling to avoid the issue entirely.
The decompression at the end of the session is gentler than the compression and most people notice very little in their ears at that stage.
3. What does it smell like in there?
Clean. Clinical. Faintly of fresh oxygen - which some people describe as a very slightly sweet, almost metallic quality, though most notice nothing at all. Nothing unpleasant. Nothing chemical.
4. Can I breathe normally?
Yes - completely normally. You'll breathe normally throughout the therapy.
Some people expect it to feel like breathing through a mask on a plane, or like the slightly laboured breathing of high altitude. It is nothing like either. The oxygen-enriched environment at elevated pressure actually makes breathing feel easier for most people, not harder. The air feels clean and full.
If you find yourself holding your breath from anxiety in the first few minutes, consciously slow down and breathe naturally. Within a few minutes of being at treatment pressure, the vast majority of people settle into a state that many describe as deeply relaxing.
5. What do most people actually do during a session?
More than anything else: rest.
If you're in a monoplace (single person) chamber, you may pass the time by watching television or a movie, sleeping, or reading.
At OxyPlus, clients bring headphones and listen to whatever they usually listen to. Some use the 60–90 minutes as enforced downtime - a space to think without distraction. Some sleep. Some catch up on a podcast series they never have time for otherwise.
Sessions are 60–90 minutes. The most common thing clients tell us after their first session is that it felt shorter than expected, and that they felt unusually calm and clear-headed afterwards.
6. Is it hot in there? Will I feel uncomfortable?
Temperature is managed in clinical hard-shell chambers and is comfortable throughout. It is not hot. Some people feel slightly warm during compression as pressure builds, but this normalises quickly once the treatment pressure is reached.
You will be dressed in loose, comfortable clothing - we ask that you avoid synthetic fabrics and wear cotton or natural materials for the session. You should not bring anything battery-powered, electronic, or flammable into the chamber. We provide a full pre-session briefing that covers all of this.
7. What does it feel like when the session ends?
The decompression phase - the last 10–15 minutes of the session as pressure gradually returns to normal - is gentle and for most people almost imperceptible. Ears may pop slightly, less so than during compression.
You may feel sleepy after hyperbaric oxygen therapy. A mild, pleasant drowsiness is common the kind you might feel after a long walk or a very restorative rest. Some clients describe feeling unusually clear-headed. Some feel energised. A small number feel briefly light-headed, which passes within a few minutes.
Some people describe a feeling of lightheadedness immediately following their session. This feeling generally lasts a few minutes.
Most clients leave feeling better than when they arrived. Very few find the post-session feeling unpleasant.
8. Are there any side effects I should know about?
HBOT is considered a safe treatment with a well-established clinical profile, but it is honest to acknowledge the side effects that can occur:
Ear and sinus pressure - the most common, and manageable with proper technique as described above. For most people this is a mild inconvenience rather than a problem.
Mild fatigue - some people feel tired after their first few sessions, particularly if they have not been sleeping well or are managing a significant health condition. This typically resolves as the course progresses. Many clients find their sleep quality improves considerably across the first few weeks.
Temporary vision changes - after 20 or more treatments, some patients may experience a change in vision. This is usually temporary and in the majority of patients, vision returns to its pre-treatment level about six weeks after the cessation of therapy. This is worth knowing about if you wear glasses - we advise not updating your prescription during or immediately after a course of HBOT.
Headache - mild headaches are occasionally reported, particularly in early sessions, and typically resolve on their own.
Oxygen toxicity - this is the side effect that sounds alarming but is exceptionally rare in the context of clinical HBOT. The risk is less than one in 10,000 treatments when sessions are conducted at appropriate pressures and durations - which ours always are. Our sessions include short air breaks during which you breathe normal air, which further minimises any risk.
Claustrophobia or anxiety - as discussed above: rare, manageable, and something we take every practical step to prevent.
9. Will I feel anything after my first session that tells me it's working?
Honestly? Sometimes not immediately - and that is fine.
Some clients notice something after their very first session: better sleep that night, a feeling of calm, a slight lift in mental clarity. Others notice nothing particular for the first few sessions and then - somewhere between sessions 5 and 10 - begin to notice changes that accumulate. This is actually the more typical pattern.
HBOT works through progressive biological mechanisms - mitochondrial biogenesis, angiogenesis, neuroplasticity - that take time to develop. A single session starts the process. The clinical benefits documented in research emerge across courses of treatment. Managing expectations here is important: HBOT is not a single-dose treatment, and first-session effects are not the measure of whether it is working.
What most clients do notice from early on, consistently, is better sleep. It is often the first tangible sign that something biological is changing - and it is a meaningful one.
10. What should I do before my first session?
A few practical things that will make your first session as comfortable as possible:
Eat beforehand. Not a heavy meal immediately before, but do not arrive fasted. A light meal 1–2 hours before is ideal. Low blood sugar during a session can cause lightheadedness.
Stay hydrated. Drink water normally before and after your session.
Wear cotton or natural fabrics. Avoid synthetic clothing, as these are not permitted in the chamber environment for fire safety reasons.
Leave electronics outside. Phones, headphones with batteries, and other electronics cannot come into the chamber. We can supply you with appropriate audio devices if needed.
Tell us about any recent health changes. If you have a cold, sinus infection, active ear problem, or have had any relevant health changes since your consultation, let us know before you get in.
Come a few minutes early. Your first session will include a full consultation - it is worth not rushing this.
And most importantly: ask us anything you are unsure about before the session begins. There are no silly questions in a hyperbaric clinic. We would rather answer ten questions before you get in than have you anxious while you are inside.
The Short Answer
HBOT feels, for most people, like a comfortable rest in a quiet space where your ears pop a bit at the start and you breathe clean air for an hour. It is not dramatic. It is not uncomfortable. It is — by far the most common description we hear — surprisingly relaxing.
The science that happens during that hour is extraordinary. But the experience of sitting through it is, in the best possible way, rather ordinary.
If you have been putting off booking because you were not sure what to expect — now you know. Come and experience it for yourself at OxyPlus, Newcastle's specialist HBOT clinic.
👉 Book your first session below