Hyperbaric Oxygen Therapy Side Effects: Ear Pressure, Sinus Discomfort and Tiredness

The chamber door closes with a soft, expensive-sounding thud, and the technician’s voice comes through the intercom: “You’ll hear a hiss. When your ears feel full, swallow or yawn. Don’t wait for it to hurt.” A man in his sixties, two months past radiation for a jaw tumor and now facing forty mornings of this, lies back on the gurney and stares at the acrylic curve above him. The hiss begins. Within a minute his ears feel the way they do on a descending airplane, only slower and more deliberate.

That fullness is the first, and by far the most common, of the hyperbaric oxygen therapy side effects people ask about. The others are quieter: a dull ache behind the cheekbones, a nap that arrives uninvited in the afternoon, reading glasses that mysteriously stop working a few weeks in.

None of this is mysterious once you understand the physics of pressure and the biology of breathing pure oxygen. This article walks through what is common, what is rare, what is myth, and which signs mean you should pick up the phone.

What actually happens during a hyperbaric oxygen session?

Hyperbaric oxygen therapy, usually shortened to HBOT, means breathing pure oxygen while the air pressure around you is raised well above normal. According to Mayo Clinic, chambers typically run at two to three times ordinary atmospheric pressure, and a session lasts around two hours including the time it takes to pressurize and depressurize.

Two kinds of chamber are in common use. A monoplace chamber is a clear acrylic tube built for one person, who lies down while the whole chamber fills with oxygen. A multiplace chamber is a room where several people sit and breathe oxygen through a hood or mask while the room itself is pressurized with ordinary air. The physics of pressure change is the same in both; the experience differs mainly in how much company you have.

The point of all this is arithmetic. At normal pressure, almost all the oxygen in your blood rides on hemoglobin, the protein inside red blood cells. Under hyperbaric conditions, far more oxygen dissolves directly into the liquid part of blood, so it can reach tissue where blood flow is poor, swelling is high or infection has taken hold. That extra oxygen is what clinicians are after when treating conditions like carbon monoxide poisoning, decompression sickness, some non-healing wounds and radiation-damaged tissue.

A session has three phases. Compression is when the pressure climbs and your ears and sinuses do most of their complaining. The treatment phase is long, quiet and often spent watching a screen through the acrylic. Decompression brings the pressure back down, gently, over several minutes. Almost every side effect in this article maps onto one of those three phases, and knowing which one helps you and your team spot what is happening.

Why does a hyperbaric chamber cause ear pain and pressure?

Your middle ear is a small air-filled pocket behind the eardrum, connected to the back of your throat by the Eustachian tube, a narrow channel that opens when you swallow or yawn. When outside pressure rises during compression, the air trapped behind your eardrum is suddenly at lower pressure than the chamber. The eardrum bows inward. If the Eustachian tube does not open to let air in and equalize, that inward pull becomes pain, and the small blood vessels in the eardrum and middle ear lining can bruise or bleed.

That injury has a name: barotrauma, which simply means tissue damage caused by a pressure difference. Middle ear barotrauma is the single most frequently reported side effect of HBOT. A systematic review published in Advances in Wound Care found reported rates ranging from a few percent to well over half of patients, the wide spread depending largely on whether researchers waited for complaints or actively examined eardrums after each session. Most cases were mild redness or fluid behind the drum; eardrum perforation was uncommon.

Hyperbaric chamber ear pain nearly always happens on the way down in pressure terms, during compression. The standard defenses are unglamorous: swallowing, yawning, moving the jaw, and a gentle pinch-the-nose-and-blow maneuver if your team has taught it to you. The technician will slow or pause the compression the moment you signal discomfort, which is why the instruction is always “tell us early.”

Some people simply cannot equalize well, especially with a cold, allergies or scarring from past ear problems. For a long course, the treating team may discuss placing small ventilation tubes through the eardrum so pressure equalizes on its own. That is a decision for you and them together, weighed against the number of sessions ahead.

Sinus discomfort: the same physics in smaller spaces

The sinuses are air pockets in the bones of the face, each draining into the nose through an opening roughly the width of a pencil lead. When those openings are clear, pressure equalizes on its own and you feel nothing. When they are swollen shut by a cold, hay fever or a recent sinus infection, the trapped air behaves exactly like the air in a blocked middle ear. During compression the sinus lining is pulled inward and can ache sharply behind the eyes or cheeks; during decompression, expanding air that cannot escape produces a pressing, sometimes stabbing pain.

Sinus barotrauma is reported far less often than ear barotrauma in the systematic review literature, and it rarely causes lasting harm. It is also the side effect most easily prevented by honesty. If you arrive congested, say so before the door closes. Many programs will postpone that day’s session rather than compress a blocked sinus, because the alternative, a painful session that may need to be aborted midway, wastes everyone’s morning.

Nasal decongestant sprays and antihistamines are sometimes discussed as ways to keep the openings clear before a session. Whether they are appropriate for you depends on your heart, blood pressure and other medicines, so treat that as a question for the prescribing clinician rather than a pharmacy-aisle decision.

A practical note on nosebleeds: a small amount of blood-streaked mucus after a session can come from the sinus lining being stretched. It usually stops on its own. Repeated or heavy bleeding, or bleeding with facial pain and fever, is a different matter and belongs in the “call your doctor” category later in this article.

Does HBOT make you tired? What the evidence actually shows

Yes, fatigue after a session is common enough that Johns Hopkins Medicine lists tiredness and lightheadedness among expected side effects. What the evidence does not do is explain it cleanly. Fatigue is rarely measured as an outcome in hyperbaric studies, so its true frequency and cause are described in clinic experience more than in numbers.

Several plausible mechanisms stack up. A two-hour session in a warm, enclosed space is physically and mentally draining in the way a long flight is, even though you barely move. Breathing pure oxygen at pressure changes how your body handles carbon dioxide and can leave some people slightly foggy afterward. The conditions that bring people to a chamber, such as chronic wounds, tissue damage after radiation or recovery from poisoning, are themselves exhausting, and forty consecutive early appointments would tire anyone. For people with diabetes, a drop in blood sugar during treatment can masquerade as ordinary tiredness, which is why many programs check glucose before and after.

What the tiredness usually looks like: a pull toward a nap in the hours after treatment, sometimes a mild headache, occasionally a light-headed spell on standing up from the gurney. What it usually does not look like: sleeping through the next day, confusion, or fatigue that gets steadily worse across the course. Those patterns deserve a conversation.

The honest summary is that post-session tiredness is real, generally mild and generally short-lived, and there is no strong evidence that it signals harm. Planning for it is more useful than worrying about it. Arrange a ride if you can, avoid scheduling demanding tasks straight afterward, eat something before you come, and mention any pattern that surprises you to the nursing team.

Hyperbaric oxygen therapy side effects at a glance: how common are they?

Numbers for hyperbaric oxygen therapy side effects vary between studies because definitions vary. A program that peers into every eardrum after every session will report far more “barotrauma” than one that only records complaints. With that caveat, the table below summarizes what the systematic review in Advances in Wound Care and the major clinical reference sites describe.

Side effect	When it typically occurs	Reported frequency	Usual course
Middle ear barotrauma (pressure, pain, fluid)	Compression phase	Most common; a few percent to over half depending on how it is assessed	Mild cases settle in days; perforation uncommon and usually heals
Sinus barotrauma	Compression or decompression	Uncommon; much rarer than ear effects	Hours to days; worse with congestion
Tiredness, lightheadedness	Hours after a session	Common in clinical experience; poorly quantified	Same day
Temporary nearsightedness	After many sessions, often beyond twenty	Common in longer courses	Returns toward baseline over weeks to months after finishing
Low blood sugar	During or after a session	Mainly in people with diabetes on glucose-lowering treatment	Corrects with food; monitored by staff
Claustrophobia, anxiety	Any phase, often early sessions	Varies widely	Often eases with familiarity and support
Oxygen toxicity seizure	Treatment phase	Rare; roughly between 1 in 2,000 and 1 in 10,000 treatments across series	Stops when oxygen is removed; no lasting damage in most reports
Lung barotrauma, collapsed lung	Decompression, or if lung disease was unrecognized	Very rare	Medical emergency

Reading down the right-hand column, a pattern emerges. The frequent effects are the trivial ones, and the dangerous effects are the rare ones. That is not an accident; it reflects decades of protocol refinement, screening before treatment and continuous monitoring during it. It is also why hyperbaric oxygen is delivered under medical supervision rather than as a spa service.

HBOT side effects on the eyes: temporary nearsightedness

Somewhere past the halfway mark of a long course, a surprising number of people notice that road signs have gone soft but the book in their lap is sharper than it has been in years. This is myopic shift, a temporary increase in nearsightedness, and Mayo Clinic lists it among the recognized side effects of hyperbaric oxygen.

The mechanism sits in the lens of the eye. Repeated exposure to high oxygen levels appears to alter the proteins in the lens so that it bends light slightly more strongly, focusing images in front of the retina rather than on it. The systematic review notes that the change tends to appear after roughly twenty or more sessions and builds gradually. The good news is in the same review: in the overwhelming majority of reports, vision drifted back toward baseline over the weeks to months after treatment ended.

Two practical consequences follow. First, do not update your eyeglass prescription mid-course. Optometrists who know a patient is receiving HBOT will usually advise waiting until the eyes have had time to settle after the final session, because a prescription written at peak shift may be wrong within a couple of months. Second, driving may need extra thought if the change is noticeable; that is a conversation for your treating team, not a judgment to make alone on the road.

Cataracts, a clouding of the lens, have been reported after very long exposures, mostly in older research involving far more sessions than typical courses. The evidence does not suggest that standard courses cause cataracts, but a pre-existing cataract may progress somewhat. Anyone with known lens changes should mention them before starting.

Sudden vision loss, a curtain across part of the visual field, flashes or a shower of new floaters are not HBOT side effects and need urgent eye assessment regardless of treatment.

The rare serious ones: oxygen toxicity seizures and lung barotrauma

Oxygen is a drug, and like any drug it has a dose beyond which it harms. Under pressure, the brain can be exposed to more oxygen than it tolerates, and the result is a seizure. Clinicians call this central nervous system oxygen toxicity. It is the event that most alarms people reading about HBOT, so it deserves a clear-eyed description.

The systematic review places the frequency somewhere between roughly 1 in 2,000 and 1 in 10,000 treatments, depending on the series, the pressure used and the population treated. Warning signs sometimes precede it: twitching of the face or lips, ringing in the ears, nausea, dizziness, tunnel vision, irritability. Staff are trained to watch for these and to switch a patient from oxygen to ordinary air at the first sign. When a seizure does occur, it stops once the oxygen exposure is reduced, and the review describes no lasting neurological injury in most reported cases. Programs build scheduled “air breaks” into treatment protocols precisely to keep the brain’s oxygen exposure below its threshold.

Fever, certain medicines, very high pressures and some underlying conditions raise the risk, which is part of why a thorough screening visit precedes treatment.

The lungs face a different hazard. Prolonged high-oxygen exposure can irritate airway lining, producing a dry cough or chest tightness; this pulmonary oxygen toxicity is uncommon at typical treatment schedules and resolves when exposure stops. Far rarer, and more dangerous, is lung barotrauma. If air is trapped in a pocket of diseased lung during decompression, it expands and can rupture into the chest cavity, causing a collapsed lung, known as pneumothorax. Mayo Clinic lists this among the recognized risks. It is why an untreated pneumothorax is an absolute reason not to enter a chamber, and why chest imaging is often part of the pre-treatment work-up for anyone with lung disease.

Low blood sugar, claustrophobia and the fire rule

Three side effects are less about pressure than about the person and the room.

Hyperbaric oxygen tends to lower blood glucose, and the effect is most relevant to people with diabetes who take insulin or other glucose-lowering medicines. The systematic review describes hypoglycemia, a blood sugar level low enough to cause symptoms, as a recognized event during and after sessions. Shakiness, sweating, sudden hunger, irritability or a fog that feels heavier than ordinary post-session tiredness are the cues. Most programs check glucose before a session and may ask you to eat beforehand. Any adjustment to diabetes medicines around treatment days is a decision for the prescribing clinician, who will weigh the timing of your sessions against your usual regimen.

Claustrophobia is the second. Lying in a clear tube for two hours is genuinely difficult for some people, and multiplace chambers, where you sit in a room with others and wear a hood, are sometimes an easier fit. Cleveland Clinic notes that anxiety in the chamber is common enough that programs routinely offer coaching, distraction such as movies, and the reassurance that the intercom is always live. Some people need a short-acting anti-anxiety medicine for early sessions; whether that is appropriate is again a matter for the treating team.

The third is fire. Pure oxygen makes ordinary things burn ferociously. Programs prohibit lighters, petroleum-based lotions, hair products, synthetic clothing, battery-powered devices and anything that could spark. This is not fussiness. Hyperbaric chamber fires are exceedingly rare precisely because these rules are enforced without exception, and cotton gowns are standard for that reason. If a rule seems arbitrary, ask; there is almost always a combustion reason behind it.

Who is usually offered hyperbaric oxygen, and who is asked to wait

The conditions with the strongest evidence share a theme: tissue starved of oxygen that a chamber can rescue. Mayo Clinic and Johns Hopkins Medicine list decompression sickness in divers, carbon monoxide poisoning, air bubbles in blood vessels, gas gangrene and other severe soft-tissue infections, crush injuries, skin grafts or flaps at risk of failing, tissue damage from radiation therapy, non-healing diabetic foot wounds, severe anemia when transfusion is not possible, and sudden unexplained hearing loss. For emergencies such as poisoning or decompression illness, treatment may be a single session or a handful. For wounds and radiation injury, Cleveland Clinic describes courses commonly running to 20 to 40 daily weekday sessions.

Being asked to wait, or being declined, is usually about safety rather than eligibility.

• An untreated collapsed lung is the one near-absolute barrier, because trapped air expands dangerously on decompression.
• A cold, sinus infection or flare of allergies typically means postponing until you can equalize, not stopping the course.
• Fever raises seizure risk and is often a reason to reschedule that day.
• Lung disease with air trapping, such as emphysema with large air pockets, needs imaging and careful assessment first.
• Poorly controlled seizure disorders, certain chemotherapy agents known to sensitize the lungs to oxygen, and some implanted devices that have not been rated for pressure all call for specialist review.
• Pregnancy is generally a reason to avoid elective courses, although carbon monoxide poisoning in pregnancy is a recognized exception where the benefit to the fetus may outweigh the risk.

Recent ear surgery, an inability to equalize despite ventilation tubes, or severe claustrophobia that cannot be managed are also reasons a team may pause and reconsider. None of these are moral judgments about a patient; each traces back to one of the side effects described above and to the team’s job of keeping the frequent ones minor and the rare ones absent.

What the following days and weeks usually look like

For a single emergency treatment, aftercare is short. Ears may feel full for a few hours, tiredness passes by the next morning, and follow-up focuses on the underlying problem rather than the chamber. Divers treated for decompression sickness are typically asked to wait before flying or diving again; the length of that wait is set by the treating team based on the illness, and it is worth asking about before you leave the unit.

A long course has its own rhythm. Week one is when ear and sinus symptoms are most noticeable, because equalizing is a skill and most people improve at it quickly. Tiredness tends to be most pronounced in the first days as the routine of early appointments settles in. By the second or third week many people report the sessions have become boring rather than daunting, which is a good sign.

Vision changes, if they come, usually arrive later, often after twenty or more sessions according to the systematic review. This is the stretch when reading glasses stop fitting and distant text blurs. Programs generally advise against changing prescriptions until several weeks after the course ends.

The last sessions bring a different set of questions: how the wound or tissue is responding, whether the planned number of treatments is still right, and what happens to any symptoms afterward. Ear fullness resolves within days for almost everyone. Tiredness lifts once the daily commute stops. Nearsightedness drifts back over weeks to months. If any symptom is still present a month or two after the final session, that is a reasonable prompt for a follow-up visit rather than something to wait out indefinitely.

Throughout, keep the same team informed about any new medicines, new illnesses or new symptoms. The screening that happened before session one is not a one-time event; it is a conversation that continues to the last day.

How long HBOT takes to work, and is it good for you?

People searching “how long does hyperbaric oxygen take to work” usually want a date. The truthful answer is that it depends entirely on what is being treated. For carbon monoxide poisoning, the goal is immediate: to flush the gas from hemoglobin and protect the brain and heart, so the benefit is measured in hours. For decompression sickness, bubbles shrink within a session, and symptoms often improve during treatment itself. For a diabetic foot wound or radiation-damaged jawbone, oxygen is not a patch but a fertilizer: it supports new blood vessel growth and the cells that build tissue, and those processes unfold over weeks. That is why Cleveland Clinic describes wound courses in the range of 20 to 40 sessions, with progress judged by the wound team at intervals rather than session by session.

“Is hyperbaric good for you?” is a different question, and it deserves a firmer answer. For the conditions listed by Mayo Clinic, Johns Hopkins Medicine and Cleveland Clinic, hyperbaric oxygen is an evidence-supported medical treatment with known benefits and the known risks described in this article. For a person who does not have one of those conditions, it is not a wellness boost, and Mayo Clinic is explicit that there is insufficient evidence for uses such as autism, cerebral palsy, Alzheimer’s disease, chronic fatigue, cancer, depression or general “anti-aging.”

That matters for side effects, too. Every ear barotrauma, every seizure risk, every hour of fatigue is a cost. In a condition where the treatment is proven, that cost is bought with benefit. In a condition where it is not, the cost is simply a cost. The honest evidence-based position is that HBOT is good for the right person with the right diagnosis, delivered under supervision, and that anyone being offered it for something outside the established list should ask which guideline or systematic review supports that use.

What people often get wrong about hyperbaric oxygen therapy side effects

Myths cluster around this treatment, partly because the chambers look futuristic and partly because they are marketed for things the evidence does not support. A few corrections.

“More oxygen is always better.” It is not. Oxygen toxicity to the brain and lungs is the reason protocols include air breaks and the reason pressures are capped. The therapeutic window is real and clinicians work inside it deliberately.

“Ear pain means something is broken.” Usually it means your Eustachian tube did not open quickly enough on that particular compression. Pain that eases when the technician pauses, and a mild fullness afterward, is barotrauma at its mildest. The systematic review found perforation to be the exception, not the rule.

“The tiredness means the therapy is working.” There is no evidence linking post-session fatigue to benefit. It is a side effect, plausibly explained by the session itself, and its presence or absence says nothing about how your wound is healing.

“Home or spa chambers are the same thing.” Soft-sided chambers that reach only slightly above normal pressure and often use room air are not medical HBOT. They deliver far less oxygen to tissue, are not supervised, and lack the screening that keeps the serious side effects rare. Reports of mild ear symptoms from such devices are not evidence they “work.”

“Side effects are permanent.” The vast majority resolve: ear fullness in days, tiredness the same day, nearsightedness over weeks to months. The rare serious events are why supervision exists, not a routine expectation.

“If it’s approved for wounds, it must help my other condition.” Approval is diagnosis-specific because evidence is diagnosis-specific. Extending a proven treatment to an unproven use means accepting the same side-effect profile without the same expected return.

Questions to ask your care team

The pre-treatment consultation is where most side effects are prevented, and the best way to use it is to arrive with questions. These are the ones hyperbaric nurses and physicians say they wish more people asked.

• Which specific condition is being treated, and which guideline or evidence supports hyperbaric oxygen for it?
• How many sessions are planned, at what pressure, and how will you decide whether to continue, shorten or stop the course?
• Will I be in a monoplace or multiplace chamber, and can I see it before my first session?
• How will you teach me to equalize my ears, and what happens if I cannot?
• Should I postpone a session if I have a cold, allergies or a fever, and who do I call on the morning to check?
• I have diabetes, lung disease, a seizure history or an implanted device: what extra checks do you recommend before starting?
• Do any of my current medicines, including chemotherapy, steroids or anything for anxiety or blood pressure, need review before treatment?
• What eye changes should I expect, and when is it sensible to have my eyeglass prescription rechecked after the course?
• What should I eat before a session, and will you check my blood sugar?
• What exactly can I bring into the chamber, and what must stay outside?
• Which symptoms should make me stop and call you the same day, and which can wait for my next appointment?
• If I am a diver or have travel planned, how long should I wait before flying or diving, and who decides?

Write the answers down. A long course involves many staff members across many mornings, and having the plan in your own hand makes it easier to notice when something departs from it. Every one of these decisions, from the number of sessions to whether a decongestant is appropriate, rests with the treating team; the questions are there to make sure you understand the reasoning behind their choices.

When to call your doctor

Most hyperbaric oxygen therapy side effects can wait for your next scheduled session, where staff will look in your ears and ask about your day. Some cannot. The list below separates the two; when in doubt, call the unit, which is staffed by people who expect these questions.

Call emergency services or go to an emergency department immediately for:

• Sudden chest pain, sharp pain on breathing, or breathlessness that comes on quickly, especially within hours of a session, which can signal a collapsed lung.
• A seizure, uncontrolled twitching, or a period of confusion or unresponsiveness after leaving the chamber.
• Coughing up blood.
• Symptoms of severe low blood sugar such as confusion, inability to eat or drink, or loss of consciousness.
• Sudden loss of vision, a curtain or shadow over part of your sight, or a burst of new flashes and floaters.

Call your treating team the same day for:

• Ear pain that persists for more than a few hours after a session, fluid or blood draining from the ear, sudden hearing loss, or spinning dizziness.
• Sinus pain with fever, facial swelling or repeated nosebleeds.
• Shakiness, sweating, unusual hunger or foggy thinking that improves with food, which suggests blood sugar is dropping around sessions.
• A new dry cough, chest tightness or breathlessness that is mild but did not exist before treatment began.
• Tiredness that is worsening across the course rather than settling, or that is accompanied by headache, nausea or ringing in the ears.
• Any new medicine, illness, fever or pregnancy, before your next session.

None of these signs mean treatment has failed, and most have straightforward explanations. What they share is that they need a clinician’s eyes rather than yours. The team that screened you before session one is the right team to decide whether to pause, adjust or continue, and reaching them early is always the safer choice.

Frequently asked questions

Can HBOT make you tired?

Yes, tiredness and lightheadedness after a session are recognized side effects, listed by Johns Hopkins Medicine among expected effects. The cause is not well studied; the long enclosed session, changes in carbon dioxide handling while breathing pure oxygen, underlying illness and, in people with diabetes, falling blood sugar all plausibly contribute. It is usually mild and gone by the next day. Fatigue that worsens across a course, or comes with confusion or headache, should be reported to your team.

How much do hyperbaric chamber sessions typically cost?

This magazine does not publish prices, and they vary so widely by indication, setting and coverage that any figure would mislead. What matters medically is whether your condition is one where evidence supports hyperbaric oxygen, because coverage decisions generally track those established indications. Ask your treating team which diagnosis is being treated and which guideline supports it, then take that information to your insurer or benefits office before starting a course.

How long does it take for hyperbaric oxygen to work?

It depends on the condition. For carbon monoxide poisoning or decompression sickness, the effect is intended within hours, often during the first session. For chronic wounds and radiation tissue injury, oxygen supports new blood vessel and tissue growth over weeks, which is why Cleveland Clinic describes courses commonly running to 20 to 40 daily sessions. Progress in those cases is judged by the wound or radiation team at intervals, not by how you feel after any single visit.

Is hyperbaric oxygen therapy good for you?

For the conditions with established evidence, such as carbon monoxide poisoning, decompression sickness, certain severe infections, non-healing diabetic wounds and radiation injury, it is a supported medical treatment with known benefits and known risks. For people without one of those diagnoses, Mayo Clinic notes there is insufficient evidence for uses like autism, Alzheimer’s disease, chronic fatigue, cancer or anti-aging. In those cases you would accept the side effects without the expected benefit.

Why do my ears hurt after a hyperbaric chamber session?

Ear pain during or after a session almost always comes from middle ear barotrauma: the pressure behind your eardrum did not equalize quickly enough during compression, so the drum was pulled inward and the lining bruised. Mild fullness or ache settling within hours to a day is the common pattern. Pain lasting longer, fluid or blood from the ear, sudden hearing loss or spinning dizziness should be reported the same day, and staff can examine the eardrum before your next session.

Are HBOT side effects on the eyes permanent?

Usually not. The main eye effect is a temporary increase in nearsightedness, caused by high oxygen exposure altering the lens, which tends to appear after around twenty sessions. The systematic review of adverse effects reports that vision returned toward baseline over weeks to months after treatment ended in most cases. Avoid changing your eyeglass prescription mid-course. Cataract progression has been described mainly after far longer exposures than standard courses; mention any known lens changes before starting.

Can hyperbaric oxygen therapy cause a seizure?

Rarely, yes. Central nervous system oxygen toxicity can trigger a seizure during the treatment phase, at rates reported between roughly 1 in 2,000 and 1 in 10,000 treatments across published series. Warning signs such as facial twitching, ringing ears, nausea or tunnel vision often come first, and staff switch patients to air at the first sign. Seizures stop when oxygen exposure is reduced, and lasting injury is not described in most reports. Fever and certain medicines raise the risk.

What should I not bring into a hyperbaric chamber?

Anything that could spark or burn readily in pure oxygen: lighters, matches, battery-powered devices including phones and hearing aids unless cleared, petroleum-based lotions or ointments, hair sprays, perfumes, synthetic clothing, and jewelry that could catch. Programs supply cotton gowns for this reason. The rules are enforced without exception because oxygen makes ordinary materials burn ferociously, and hyperbaric fires remain extremely rare precisely because of that discipline. If a rule seems odd, ask the technician why.

Does hyperbaric oxygen affect blood sugar?

It can lower it. Hypoglycemia, a blood sugar level low enough to cause symptoms, is a recognized event during and after sessions, mainly in people with diabetes who take insulin or other glucose-lowering medicines. Shakiness, sweating, sudden hunger or unusual fogginess are the cues. Most programs check glucose before treatment and may ask you to eat beforehand. Any change to your diabetes medicines around session days is a decision for the prescribing clinician, not something to adjust on your own.

Can I have hyperbaric oxygen with a cold or sinus infection?

Usually the session is postponed rather than the course stopped. Congestion blocks the narrow openings that let your middle ear and sinuses equalize, which makes barotrauma far more likely and more painful. Tell staff before the door closes if you are congested, feverish or have new ear symptoms; fever also raises the risk of oxygen toxicity. Whether a decongestant is appropriate to help you continue depends on your other health conditions and is a question for your treating clinician.

References

• Cleveland Clinic — Hyperbaric Oxygen Therapy
• MedlinePlus Medical Encyclopedia — Hyperbaric oxygen therapy
• Heyboer M et al. Hyperbaric Oxygen Therapy: Side Effects Defined and Quantified. Advances in Wound Care (PubMed Central)

This article is for general information only and is not a substitute for professional medical advice. Please consult a qualified doctor about your individual situation.