Most drug-store drugs are safe to continue during HBOT. A small group have well-documented issues that warrant pause, dose change, or total caution. This article walks through the major ones.
We pulled the UHMS position statements, FDA boxed warnings, and published case reports to summarize the drug-HBOT issue picture. The FDA has cleared HBOT for 13 set uses (FDA 2021). Drug issues apply across both cleared and off-label use.
The single most important rule: bring a complete drug list to your first HBOT visit. The hyperbaric doctor will flag anything that needs care.
Total no-go drugs
Two drugs warrant total caution with HBOT.
Bleomycin (a chemo agent used for testicular cancer, lymphoma, and other malignancies) carries a black-box warning for HBOT. Patients with prior bleomycin exposure can develop fatal lung fibrosis when given high-dose oxygen, including HBOT. The risk persists for life (Donat & Levy 1998).
If you have ever received bleomycin chemo, tell the hyperbaric doctor right away. Most UHMS programs will not provide HBOT to prior bleomycin patients without exhaustive risk evaluation. In most cases the answer is no.
Disulfiram (Antabuse, used for alcohol use disorder) blocks the body's oxygen detoxification pathway. Patients on disulfiram are at higher risk for HBOT oxygen harm. Most programs stop disulfiram for the course of HBOT (Hampson & Atik 2003).
Relative no-go drugs
Several drugs require careful care or dose change during HBOT.
Doxorubicin (chemo) carries some HBOT concern through similar mechanisms to bleomycin. Risk is lower than bleomycin but warrants caution. Discuss with your oncologist and hyperbaric doctor (Marx 1990).
Cisplatin (chemo) can impair wound healing in ways that may interact with HBOT for wound care uses. Time HBOT relative to chemo cycles when possible.
Mafenide acetate (Sulfamylon, topical burn dressing) inhibits carbonic anhydrase and can worsen the metabolic acidosis sometimes seen with HBOT. Most burn programs hold mafenide on HBOT days.
For patients on chemo with an FDA-cleared HBOT use (radiation harm from cancer treatment is the most common), see our HBOT for radiation tissue damage review for coordination guidance.
Diabetes drugs: dose change needed
HBOT lowers blood glucose during and after sessions (Trytko & Bennett 2003). The effect is most pronounced in the first few sessions of a course.
This matters for diabetic patients, who make up most of the FDA-cleared HBOT population (diabetic foot ulcer). Insulin and oral diabetes drug doses often need change during HBOT courses.
Standard practice at UHMS hospital wound programs running Sechrist Industries or Perry Baromedical chambers:
- Test blood glucose before each session
- Test again 1-2 hours after the session
- Hold or reduce short-acting insulin on HBOT days
- Coordinate with the patient's endocrinologist for ongoing changes
Patients on metformin alone usually need no change. Patients on insulin, sulfonylureas (glipizide, glyburide), or combination plans often do.
Soft-shell wellness HBOT at 1.3 ATA in OxyHealth or Summit to Sea chambers (common at Restore Hyper Wellness) has less effect on blood glucose. Hard-shell hospital HBOT at 2.0-2.4 ATA has the most.
Seizure threshold drugs
HBOT can lower the seizure threshold at high pressures. Drugs that further lower the threshold may increase the rare oxygen-harm seizure risk.
Drugs in this category include:
- Tramadol — modest seizure risk
- Bupropion (Wellbutrin) — modest risk
- Theophylline — modest risk
- High-dose aminoglycoside antibiotics — modest risk
Most hyperbaric doctors will not stop these drugs but will be more cautious with chamber pressure and session length. Tell the team about any history of seizures.
The actual risk is low. Oxygen harm seizures occur roughly 1 in 10,000 sessions at 2.0-2.4 ATA (Plafki 2000).
Hypertension drugs
Most blood pressure drugs work fine during HBOT. The chamber's hyperoxia can cause mild reflex bradycardia and slight blood pressure changes in some patients.
ACE inhibitors, ARBs, beta-blockers, and calcium channel blockers are usually kept without modification during HBOT courses. The hyperbaric doctor will note your home plan.
Patients on multiple antihypertensives or with unstable blood pressure may benefit from a baseline session monitoring before continuing the standard protocol.
Anticoagulants and antiplatelet drugs
Warfarin, direct oral blood thinners (DOACs like apixaban, rivaroxaban), aspirin, and clopidogrel are usually kept during HBOT. There is no set HBOT issue.
The relevant consideration is ear ear harm. Patients on blood thinners who develop ear ear harm may bleed more. The risk is small but real.
Most programs do not stop blood thinners for HBOT. They may use slower pressure ramps for anticoagulated patients who report ear discomfort.
Steroids
Systemic steroids (prednisone, dexamethasone) raise some concerns about HBOT-induced problems. The published data is limited.
For steroid-dependent patients with an FDA-cleared HBOT use, the typical approach is to continue the steroid at the lowest necessary dose and proceed with HBOT.
Topical steroids and inhaled steroids have no set HBOT issue.
Diuretics
Diuretics can contribute to water loss, which makes Eustachian tube clearing harder during HBOT. Patients on loop diuretics (furosemide) or thiazides should ensure adequate water intake on HBOT days.
The drug itself is fine. The water intake status is what matters.
Recreational and over-the-counter products
A few notes on non-drug-store products.
Alcohol within 24 hours of HBOT raises water loss risk and can affect pressure perception. Most programs prohibit HBOT under the influence.
Nicotine (cigarettes, vapes, gum, patches) constricts blood vessels and reduces tissue oxygen delivery. This is particularly relevant for wound-care HBOT, where the goal is improved tissue oxygen. Many programs strongly encourage nicotine cessation during the HBOT course.
Cannabis has no set HBOT issue but can affect cognitive assessment during sessions. Disclose use to the hyperbaric doctor.
High-dose vitamin supplements (especially antioxidants like vitamin C, E, glutathione) theoretically may reduce HBOT's oxidative signaling. Evidence is limited.
Pediatric considerations
Pediatric HBOT drug issues follow the same patterns as adult ones. For more on pediatric protocols, see our pediatric HBOT chambers overview.
Most children on HBOT for FDA-cleared uses can continue routine drugs. The hyperbaric doctor will review each case.
Special case: drugs during off-label HBOT
For patients pursuing off-label HBOT for conditions like long COVID, brain harm, or chronic fatigue, the drug picture is the same as for FDA-cleared HBOT. The drug-HBOT issues do not change with use.
Aviv Clinics and similar premium off-label programs typically do a comprehensive drug review before starting. The 60-session protocol used at Aviv has the same drug issue concerns as standard 40-session wound-care HBOT. See Aviv Clinics evidence vs. marketing for the marketing-vs-evidence breakdown.
We unpack the off-label HBOT landscape in our Aviv data-vs-marketing analysis and HBOT for ADHD data review. See the HBOT-for-ADHD evidence in detail for the trial-by-trial ADHD evidence breakdown.
What to bring to your first HBOT visit
Bring a complete written drug list including:
- Prescription drugs (name, dose, schedule)
- Over-the-counter drugs (NSAIDs, antihistamines, sleep aids)
- Supplements and vitamins
- Topical creams and ointments
- Recent (past 6 months) chemo history
- Any history of seizures or oxygen-related reactions
For more on what to bring physically to a session, see our what to bring to an HBOT session guide.
What to expect during your first review
The hyperbaric doctor will look at the list and check for:
- Bleomycin history (immediate stop)
- Disulfiram use (likely hold)
- Diabetes plan (likely adjust)
- Seizure-threshold drugs (likely caution)
- Smoking status (likely encourage cessation)
Most patients have no significant changes. The doctor will document the plan and may communicate with your prescribers about any changes.
When to update your HBOT team
Tell the HBOT program if any of the following happen during your course:
- A new drug-store is started
- A dose changes significantly
- You have a chemo session
- You receive new vaccinations
- You start a new supplement
A 10-second mention at check-in can prevent serious problems.
Bottom line
Most drug-store drugs are safe to continue during HBOT. Bleomycin is an total no.
Disulfiram is usually held. Diabetes drugs need active care.
The single best practice is full disclosure of all drugs and supplements at the first HBOT visit. The hyperbaric doctor will flag what needs care.
For broader pre-session guidance, see our HBOT and nutrition pre-session guidelines.
Related Reading
- HBOT and nutrition pre-session guidelines
- What to bring to an HBOT session
- How to equalize your ears in a hyperbaric chamber
- HBOT for elderly patients: safety considerations
- HBOT side effects and safety
Frequently asked questions
Can I take my regular blood pressure drug before HBOT?
Yes, in most cases. ACE inhibitors, ARBs, beta-blockers, and calcium channel blockers are usually kept without change.
What if I had bleomycin chemo years ago?
Tell the hyperbaric doctor right away. Bleomycin carries a lifetime no-go for HBOT due to the risk of fatal lung fibrosis. In most cases, the program will not provide HBOT.
Do I need to stop my diabetes drugs?
Not usually, but dose change is often needed during the course. HBOT lowers blood glucose. Test before and after each session and coordinate with your endocrinologist.
Can I drink coffee or alcohol before HBOT?
Coffee in moderation is fine. Alcohol within 24 hours of HBOT is usually prohibited because of water loss risk and effect on pressure perception.
What about my over-the-counter pain reliever?
NSAIDs (ibuprofen, naproxen) and acetaminophen have no set HBOT issue. Tell the hyperbaric doctor about regular use.
Medical disclaimer: This article is informational and does not constitute medical advice. HBOT carries real risks including ear ear harm, oxygen harm, and chamber fire. Discuss any HBOT plan with a doctor trained in undersea and hyperbaric medicine before starting. Bring a complete drug list, including chemo history, to your first HBOT visit.
-- The HBOT Finder Team