The evidence is promising, but it is not conclusive. The strongest recent trial involved 47 people. We publish that number beside the result because one modest study does not settle the question.
If headaches, poor sleep, dizziness, light sensitivity or brain fog have continued for months, hyperbaric oxygen therapy may be a reasonable option to explore—with clear expectations about the evidence and commitment involved.
First, what the treatment is
More oxygen, delivered under pressure.
Hyperbaric oxygen therapy means breathing concentrated oxygen inside a pressurised chamber. At our Cardiff hospital, the chamber runs at 1.5 ATA and delivers 93–98% oxygen—about seven times the oxygen in ordinary air. The pressure helps more oxygen enter the bloodstream and reach tissue. That is the mechanism. Whether it improves persistent symptoms after a brain injury is still being studied.
The strongest recent trial
What researchers found.
A 2025 double-blind, sham-controlled trial studied adults whose symptoms had continued for between six months and ten years after a non-stroke brain injury. Participants received 40 chamber sessions over 12 weeks.
- Symptom improvement, HBOT
- 10.6NSI points
- Symptom improvement, sham
- 3.6NSI points
- Difference
- 7.0
- Participants analysed
- 47
95% CI 1.7–12.3; p=0.01.
One modest trial.
The HBOT group reported the larger improvement. Both groups improved in some areas, and the study was small. It is a positive result—not proof that everyone will benefit.
Read the study in Scientific Reports ↗Evidence at a glance
The positive result and the protocol behind it.
Pressure match
1.5 ATAThe same pressure our chamber uses.
Studied schedule
40 sessionsOver 12 weeks—not a ten-session Course.
Trial size
47 peopleEncouraging controlled evidence; still one modest study.
Why the pressure matters
The study used 1.5 ATA.
That is the pressure our chamber runs at. We are not borrowing a result from a higher-pressure protocol and presenting it as the same treatment. The oxygen delivery was not identical, so we do not call the complete protocols identical either.
Why the session count matters
The study used 40 sessions.
Our Course includes ten. A 40-session programme is four linked Courses for £3,000. Ten sessions may be a useful first review point, but they are not the full research protocol.
A measured way to try it
Start with facts. Keep a record of what changes.
A single session cannot reproduce a 40-session study, but it can show you whether the chamber feels manageable. If you continue with a longer plan, progress can be reviewed at sensible intervals rather than relying on memory alone.
Questions people ask.
How long can concussion symptoms last—and is it too late if the injury happened years ago?
Persistent post-concussion symptoms can last for months or years. The HBOT trial included injuries from six months to ten years earlier. That tells us who was studied; it cannot predict an individual result.
Why are you discussing 40 sessions?
Because the positive trial used 40. Selling ten while implying it reproduced that result would be misleading.
Do I need a referral to book?
No referral needed. Every Course includes a medical consultation. You can book online. We send one consent and medical declaration around 24 hours before your first session, and reception handles the routine process.
What if this is a recent head injury?
New or worsening symptoms need appropriate acute medical assessment. This page concerns symptoms that have persisted after the initial injury.