Is Hyperbaric Oxygen Therapy Safe? Side Effects and Who Should Avoid It

Hyperbaric oxygen therapy is generally considered safe when it follows a proper health consultation and is run by trained staff, but it is not suitable for everyone. The most common side effect is ear discomfort from the pressure change, similar to a plane coming in to land. Serious side effects are rare, and most are linked to much higher pressures or very long courses than those used in wellness clinics.

This guide covers the side effects you might notice, who should avoid HBOT or check with a doctor first, and the practical safety rules inside a chamber. It is general information, not medical advice. If you have a health condition, speak to your GP before booking.

Common side effects

Ear pressure and discomfort

As the chamber pressurises, pressure builds on your eardrums in the same way it does on a descending plane. Most people clear it by swallowing, yawning or gently holding the nose and blowing. In rare cases, if the ears do not clear, it can cause pain, fluid behind the eardrum or, very rarely, a perforated eardrum. The Undersea and Hyperbaric Medical Society describes middle ear barotrauma as the most common side effect of HBOT. If your ears will not clear, tell the staff running your session so pressurisation can be slowed or paused.

Sinus pressure

Blocked sinuses can cause a feeling of pressure or a headache. This is more likely if you have a cold, hay fever or a sinus infection, which is why we ask you to rebook if you are congested.

Tiredness

Many people feel relaxed or sleepy after a session. It usually passes within a few hours. Some people prefer not to drive straight after their first session until they know how they feel.

Feeling enclosed

Some people feel anxious in an enclosed space. A 15 minute trial is a good way to find out how you feel before committing to a full session.

Rare side effects

• Temporary changes in eyesight. Some people notice short sightedness after a long course of clinical HBOT, often 20 or more sessions at high pressure. It usually returns to normal within weeks of finishing.
• Oxygen toxicity. Seizures caused by oxygen are very rare and are associated with the higher pressures used in medical hyperbaric units.
• Lung injury. Very rarely, pressure changes can injure the lungs, mainly in people with existing lung problems.

Who should avoid HBOT or check with a doctor first?

HBOT may not be suitable, or needs medical advice first, if any of these apply to you:

• A collapsed lung (pneumothorax) now or in the past
• Lung conditions such as COPD or emphysema
• A cold, fever, chest infection or blocked sinuses on the day
• Recent ear surgery, ear injury or a perforated eardrum
• Pregnancy
• Heart conditions, including heart failure
• Epilepsy or a history of seizures
• Asthma, unless your doctor is happy that it is well controlled
• Some medications, including certain cancer treatments, which is why we ask for a full medication list
• Severe claustrophobia

This list is not complete, which is why every new client at 360 Degree Clinic has a consultation before their first session. We will ask about your health history, medication, ears and sinuses, and we will not book a session if we think it is unsuitable for you.

Safety rules inside the chamber

The main safety risk with any oxygen rich environment is fire, so the rules are strict:

• Wear loose cotton clothing, not synthetic fabrics
• Leave phones, lighters, vapes, batteries and electronic devices outside
• Skip perfume, hair products and oil based creams on the day
• Remove jewellery and hair clips

Our guide to what happens during a hyperbaric session covers preparation step by step.

Can you fly after hyperbaric oxygen therapy?

Flying involves another change in pressure, so many providers advise waiting at least 24 hours after a session before you fly, and longer after a long course. If you are also scuba diving, ask for specific advice, as diving and HBOT both affect how your body handles pressure.

Why are some doctors sceptical of HBOT?

In the NHS, hyperbaric oxygen therapy is used for specific medical indications, such as decompression illness in divers and gas embolism, at specialist centres. The evidence for many of the wider uses promoted online is still limited, and the Advertising Standards Authority has ruled against clinics that claimed HBOT treats conditions without robust evidence. Scepticism about exaggerated claims is healthy. At 360 Degree Clinic we offer HBOT as a wellbeing service, and we do not claim it treats or cures any medical condition.

Is hard shell HBOT at 1.5 ATA safe?

Our chamber is a hard shell chamber running at 1.5 ATA, which is well below the pressures typically used in hospital hyperbaric units. The same principles apply at every pressure: a consultation first, clear ears before and during pressurisation, and the chamber safety rules followed every time. Read more about the difference between soft and hard shell chambers.

Try it safely

If you are unsure how you will find it, start with our 15 minute trial with consultation for £50. One hour sessions are £75 until 30 November 2026 (usually £120). See our guide to HBOT costs and the current HBOT offer.

Frequently asked questions

Is hyperbaric oxygen therapy safe?

It is generally considered safe when it follows a health consultation and is run by trained staff, but it is not suitable for everyone. The most common side effect is ear discomfort from the pressure change, and serious side effects are rare.

What are the side effects of HBOT?

The most common are ear pressure or pain, sinus pressure and tiredness after a session. Rarer effects include temporary short sightedness after long courses, and, very rarely, oxygen related seizures or lung injury, mainly at the higher pressures used in hospital units.

Who should not have hyperbaric oxygen therapy?

People with a current or past collapsed lung, some lung conditions such as COPD, a cold or blocked sinuses on the day, recent ear surgery or injury, pregnancy, and some heart conditions, seizure disorders or medications should not have HBOT, or should get medical advice first. A consultation checks this before your first session.

Is hyperbaric oxygen therapy safe for people with asthma?

It depends on how well controlled your asthma is. Speak to your GP first and tell us at consultation, so we can decide together whether a session is suitable.

Can you fly after hyperbaric oxygen therapy?

Many providers advise waiting at least 24 hours after a session before flying, and longer after a long course, because flying involves another pressure change.

Does hyperbaric oxygen therapy make you tired?

Many people feel relaxed or sleepy after a session. It usually passes within a few hours.

Why are doctors against hyperbaric oxygen therapy?

Most doctors are not against HBOT itself, which the NHS uses for conditions such as decompression illness. They are sceptical of claims that it treats a wide range of conditions, because the evidence for many of those uses is still limited.