HBOT Contraindications: Who Should NOT Have Hyperbaric Oxygen Therapy?

Hyperbaric oxygen therapy is generally safe in a certified chamber — but it is not suitable for everyone. This guide explains the main HBOT contraindications: who should not have it, who needs extra caution, and why. Suitability is always decided by individual assessment before your first session.

What is hyperbaric oxygen therapy?

Hyperbaric oxygen therapy (HBOT) means breathing near-100% oxygen inside a pressurised chamber, usually around 2.0 ATA. At that pressure far more oxygen dissolves into the blood plasma and reaches tissues a normal breath cannot. For the full picture, see our hyperbaric oxygen therapy guide and hyperbaric chamber guide.

Absolute contraindications (HBOT should not be given)

The clearest reason not to have HBOT is an untreated collapsed lung (pneumothorax), because raising and lowering pressure can make it dangerous. A small number of medications also make HBOT unsafe — your doctor and the hyperbaric team will screen for these before you start.

Relative contraindications (extra caution / individual assessment)

• Ear and sinus problems — recent ear surgery, blocked sinuses or an active cold can make equalising pressure difficult.
• Certain lung conditions — significant COPD or air trapping needs careful assessment.
• Uncontrolled seizures / epilepsy — high oxygen can rarely trigger seizures, so this is reviewed carefully.
• High fever — may increase seizure risk and is usually postponed.
• Claustrophobia — manageable with acclimatisation, but disclose it.
• Implanted devices — pacemakers and pumps must be confirmed as pressure-rated.

Is HBOT safe for heart patients?

Most cardiac histories are handled by individual assessment rather than a blanket yes or no. Some unstable heart conditions require caution, and your cardiologist should be involved. Always disclose your full cardiac history and medications; a good centre will not proceed without clearing this first. For the general picture, see is HBOT safe.

HBOT and pregnancy

HBOT is generally avoided during pregnancy except in specific emergencies (such as carbon monoxide poisoning) where the benefit clearly outweighs the risk, and only under specialist supervision. If you are or may be pregnant, tell the clinic before any session.

What about oxygen toxicity?

Breathing high-pressure oxygen for too long can, rarely, cause oxygen toxicity affecting the lungs or, very rarely, trigger a seizure. This is why sessions use controlled pressures and time limits, and why an uncontrolled seizure disorder is assessed so carefully. Delivered correctly, these events are uncommon.

The bottom line

Being on this list does not automatically rule you out — many “relative” issues are managed with the right precautions. What matters is an honest medical history and a proper pre-treatment assessment. Never withhold conditions or medications to qualify for treatment.

For more on safety, see is HBOT safe and HBOT side effects. Insist on a PVHO-certified hard chamber — see hard vs soft chamber — and find a centre via HBOT near me.

How the pre-treatment assessment works

A responsible centre will not simply take your booking and start. Expect a review of your medical history and current medications, questions about your lungs, ears, heart and any seizures, and a check for pregnancy where relevant. They should confirm any implanted device is pressure-rated and ask about recent surgery or infections that affect the ears and sinuses. This is not bureaucracy — it is how genuine contraindications are caught before they become a problem, and how “relative” issues are managed safely with the right precautions. If a clinic is willing to skip this step or pressures you to start the same day without questions, treat that as a warning sign rather than convenience.

If you are unsure whether something in your history rules you out, the safest step is simply to ask before booking. Share your full picture with the clinical team and let them make the call with you; many people who assume they cannot have HBOT are in fact suitable with sensible precautions, while a few who assume it is harmless genuinely should not proceed. An honest conversation up front protects you and gives you a clear, personalised answer.

One more reassurance: for the vast majority of healthy adults seeking HBOT for a recognised reason, none of this presents a problem — the assessment is quick and the treatment proceeds normally. Listing contraindications is not meant to alarm you, but to make sure the small number of people for whom HBOT is genuinely unsafe are identified in advance, and that everyone else can proceed with confidence.

Key takeaways

• Untreated collapsed lung (pneumothorax) and certain medications are the clearest reasons to avoid HBOT.
• Heart conditions and pregnancy are handled by individual assessment, not blanket rules.
• Ear/sinus issues, uncontrolled seizures and unrated implants need caution.
• A proper pre-treatment assessment is essential — never hide conditions to qualify.

Frequently asked questions

What are the contraindications for HBOT?

The clearest absolute contraindication is an untreated collapsed lung (pneumothorax), plus certain medications. Relative cautions include ear/sinus problems, some lung conditions, uncontrolled seizures, high fever and unconfirmed implanted devices.

Can hyperbaric oxygen therapy be harmful?

Delivered correctly in a certified chamber it is generally safe. Harm is rare and usually relates to pressure effects on the ears or, very rarely, oxygen toxicity, which controlled protocols are designed to prevent.

Is HBOT safe for heart patients?

Most cardiac histories are assessed individually rather than with a blanket answer. Some unstable conditions need caution, so disclose your full history and involve your cardiologist.

Is HBOT safe during pregnancy?

HBOT is generally avoided in pregnancy except in specific emergencies like carbon monoxide poisoning, under specialist supervision. Tell the clinic if you are or may be pregnant.

What is oxygen toxicity in HBOT?

Breathing high-pressure oxygen too long can rarely affect the lungs or trigger a seizure. Controlled pressures and time limits make this uncommon.

Does a relative contraindication mean I cannot have HBOT?

Not necessarily. Many relative issues are managed with precautions. What matters is an honest history and a proper pre-treatment assessment.

This page is for education and is not medical advice. Always consult a qualified clinician before starting HBOT.