Air travel is convenient but not always safe for everyone. If you or a loved one are planning a trip, knowing the health conditions you should not fly with can prevent emergencies, denied boarding, or worsening illness midflight. This guide lists the most important conditions to watch for, explains why altitude and cabin environments can be dangerous, and gives practical steps to get medical clearance or choose an alternative.
Top health conditions you should not fly with
Below are 24 conditions that commonly make commercial air travel unsafe. For each one you will find a short explanation and, when available, typical waiting periods or criteria to consider before flying. These are general guidelines. Always confirm with your treating clinician and your airline.
Recent heart attack (myocardial infarction)
- Why this matters: Risk of recurrent cardiac events and need for urgent care. Cabin stress and limited immediate intervention increase danger.
- Typical wait time: Many clinicians recommend waiting at least 2 to 3 weeks after an uncomplicated heart attack and clearance by a cardiologist before flying.
Unstable angina or ongoing chest pain
- Why this matters: Symptoms suggest active cardiac ischemia. Do not fly until symptoms are controlled and a cardiologist clears travel.
Recent stroke (ischemic or hemorrhagic)
- Why this matters: Risk of deterioration and need for monitoring. Blood pressure instability and clot-related issues pose extra risk.
- Typical wait time: At least 2 weeks for mild strokes, often longer for large strokes. Clearance required.
- Severe heart failure or recent hospital admission for heart failure
- Why this matters: Reduced cardiac reserve makes hypoxia and cabin pressure changes risky. Monitor for fluid overload during travel.
Severe chronic obstructive pulmonary disease (COPD) or uncontrolled asthma
- Why this matters: Low cabin oxygen and respiratory infections increase risk of respiratory failure.
- Practical note: If resting oxygen saturation on room air is under roughly 92% you likely need assessment for in-flight supplemental oxygen.
Oxygen dependence at sea level
- Why this matters: Airlines need advance notice and often require that oxygen be supplied either by the carrier or a certified portable oxygen concentrator.
Pneumothorax (collapsed lung) within the past 7 to 14 days
- Why this matters: Gas expands at altitude. A recently treated pneumothorax can recur. Typical recommendation is wait at least 7 days after chest tube removal and have a follow-up chest x-ray showing no recurrence.
Recent major surgery, especially involving the chest, abdomen, or inner ear
- Why this matters: Trapped air in body cavities, risk of bleeding, and pain make flying unsafe until healed. Specific timing depends on the operation.
Recent eye surgery (retinal surgery, gas bubble in eye)
- Why this matters: Gas used in some retinal procedures expands at altitude and can cause serious vision loss. Do not fly until your ophthalmologist confirms it is safe.
Recent scuba diving or decompression illness
- Why this matters: Gas bubbles can persist after diving. Typical wait times: 12 to 24 hours after a single no-decompression dive, and at least 24 to 48 hours after multiple or decompression dives; follow dive medical guidance.
Deep vein thrombosis (DVT) or recent pulmonary embolism
- Why this matters: Immobilization and cabin pressure changes can worsen clots or increase risk of embolization.
- Typical wait time: At least 2 weeks after a provoked DVT if clinically stable; longer if anticoagulation is not therapeutic.
Active bleeding or clotting disorders
- Why this matters: Limited access to immediate care and pressure changes can exacerbate bleeding or clotting.
Severe anemia (low hemoglobin)
- Why this matters: Reduced oxygen-carrying capacity combined with lower cabin oxygen increases hypoxia risk. Many airlines and clinicians suggest a minimum hemoglobin threshold before long flights.
Sickle cell disease in crisis
- Why this matters: Hypoxia and dehydration precipitate vaso-occlusive crises. Flying during an acute episode is unsafe.
Active, contagious infectious diseases (measles, chickenpox, influenza, active COVID-19 with symptoms)
- Why this matters: Risk to other passengers and potential for rapid deterioration in a confined cabin.
Immunocompromised patients with uncontrolled infection
- Why this matters: Reduced ability to fight infections and potential exposure to pathogens in crowded airports and aircraft.
Uncontrolled seizure disorder
- Why this matters: Risk of in-flight seizures and lack of immediate medical support. Stable seizure control and a physician letter are usually required to travel.
Severe psychiatric instability or active suicidal ideation
- Why this matters: Safety of the passenger and others. Airlines may decline to transport individuals who present risk.
Late-stage pregnancy
- Why this matters: Risk of in-flight delivery and complications. Most airlines restrict travel after 36 weeks for single pregnancies and earlier for multiples.
- Typical rule: Many carriers require a doctor’s note after 28 weeks and will not accept women after 36 weeks.
Recent abdominal surgery or bowel obstruction
- Why this matters: Pain, risk of vomiting, and trapped gas with expansion can worsen recovery.
Recent dialysis complications or unstable renal failure
- Why this matters: Fluid and electrolyte instability and need for dialysis scheduling complicate long trips.
Inner ear disorders like severe Ménière disease during an active episode
- Why this matters: Pressure changes can worsen vertigo and vomiting and increase risk of falls or incapacitation.
Recent organ transplant with unstable recovery
- Why this matters: High infection risk, intensive immunosuppression, and care needs make travel risky until stable.
Severe cognitive impairment or dementia with poor ability to consent or follow instructions
- Why this matters: Safety concerns, inability to manage emergencies, and potential for agitation in transit.
Why flying can worsen medical problems
Airplanes cruise at altitudes that require cabin pressurization. Pressurization keeps passengers comfortable but still results in a cabin altitude commonly equivalent to 6,000 to 8,000 feet. Several physiologic effects matter:
- Lower available oxygen. Oxygen partial pressure is lower at cabin altitude. People with limited respiratory or cardiac reserve are at risk for hypoxia. Clinically significant hypoxia symptoms include shortness of breath, confusion, rapid heart rate, and bluish lips or fingertips.
- Gas expansion. Boyle’s law means gas in enclosed spaces expands as ambient pressure drops. This affects recent surgical sites, gas-filled eye surgeries, and chest injuries like pneumothorax.
- Dehydration and low humidity. Cabin humidity is often under 20 percent. Dehydration raises blood viscosity and can worsen clot risk and general weakness.
- Immobility and clot risk. Long sits increase risk of DVT. Passengers with clotting disorders or prior DVT need preventive measures.
- Limited access to immediate advanced care. Cabin crew are trained in first aid but cannot provide diagnostic testing or advanced interventions available in a hospital.
Specific oxygen and saturation guidance
- General guidance: If a patient’s resting oxygen saturation on room air is below about 92 percent at sea level, an evaluation is needed. Many airlines and clinicians will require supplemental oxygen or deny travel until oxygenation improves.
- COPD exception: Some COPD patients have lower baseline saturations. Decisions must be individualized with arterial blood gas or pulse oximetry testing during activity and a trial of supplemental oxygen if indicated.
Always obtain a medical clearance letter that documents baseline vitals, oxygen needs, and travel tolerance.
Can I fly? A practical decision checklist
Use this quick flow to decide whether to pursue commercial travel or an alternative.
- Is the condition on the list above active right now? If yes, do not fly until stable and cleared.
- Has the patient been hospitalized or had surgery within the past 2 weeks? If yes, seek medical clearance.
- Are there new or worsening symptoms: chest pain, shortness of breath at rest, severe dizziness, uncontrolled bleeding, or worsening neurologic signs? If yes, do not fly.
- Is oxygen required at rest or with minimal exertion? If yes, arrange oxygen and airline approval or consider a medical flight.
- Is the traveler contagious or immunocompromised? If contagious, postpone. If immunocompromised, consult infectious disease and the airline for protections.
- Are you in late pregnancy or recently postpartum with complications? Check airline policy and get a doctor’s note.
Typical waiting periods after common events (general guidance)
- Uncomplicated myocardial infarction: 2 to 3 weeks
- Stroke: minimum 2 weeks for mild cases, often longer
- Pneumothorax: at least 7 days after tube removal plus clear chest x-ray
- Major abdominal or thoracic surgery: varies, commonly 1 to 6 weeks depending on procedure
- Scuba diving: 12 to 48 hours depending on dive profile
When in doubt, request a formal “fit to fly” or medical clearance letter from the treating physician. Airlines will often ask for a MEDIF form (Medical Information Form) that documents fitness to travel.
How to get ready if flying is permitted
If your clinician clears travel, follow these practical steps to reduce risk.
Pre-flight medical steps
- Obtain a written medical clearance. Include diagnosis, stability, vital signs, oxygen requirements, medications, and recommended in-flight care.
- Complete airline medical forms early. Many carriers require a MEDIF 48 to 72 hours in advance.
- Arrange supplemental oxygen if needed. Airlines have specific policies and approved portable oxygen concentrators. Confirm the model the airline accepts.
- Plan mobility assistance. Request wheelchair or cabin-seating help ahead of time.
- Time medications to new time zones. Use a dosing plan and carry a small timezone chart or set phone alarms.
- Pack a doctor letter and recent test results in your carry-on.
What to pack in your carry-on
- All medications in original labeled containers and a copy of the prescription
- Doctor’s medical clearance letter and recent discharge summaries
- Phone numbers for treating clinicians and local emergency contacts
- A small first-aid kit, supplies for glucose monitoring if diabetic, and extra inhalers or epinephrine if prescribed
- Anticoagulants: bring a letter about dosing schedule and bridging plans if applicable
- Portable battery packs for any medical devices and a list of model numbers and voltage
How to communicate with airline staff
- Call the airline early. Explain the condition, any oxygen needs, mobility assistance, and MEDIF requirements.
- Keep communications concise. Example script: “My name is X. I need to travel on [date]. My doctor cleared me to fly but I will need onboard oxygen [or wheelchair assistance]. Which forms do you require and can you confirm acceptance?”
- At the airport, present your medical letter and be ready for additional screening.
Packing and preparation resources
- For a detailed packing checklist specific to medical flights, see Packing for a Medical Flight.
Alternatives if you cannot fly commercially
If commercial travel is unsafe, several options exist depending on urgency, distance, and resources:
- Medical escort on a scheduled flight. A clinician accompanies the patient and monitors their condition. This is suitable if the patient is stable but requires supervision.
- Air ambulance. For seriously ill or unstable patients, a dedicated air ambulance provides onboard hospital-level care and oxygen systems. To learn how to arrange this, see How to Arrange an Air Ambulance Flight.
- Ground ambulance or private medical transport for shorter distances. This can be safer for people who cannot tolerate pressurized cabins. Compare options in Ground Transport vs. Air Ambulance.
- Medical repatriation services for international returns when patients cannot travel commercially. For an overview of how repatriation works, review Medical Repatriation Explained.
Costs and insurance considerations
- Air ambulances are costly. Check whether your insurance covers medical transport and whether trip insurance or evacuation coverage is available.
- Ask for a written cost estimate and compare the expense of a medical escort plus commercial flight to air ambulance quotes.
What to do if you are denied boarding
Airlines can deny boarding on medical grounds if staff or medical advisors determine travel is unsafe. If denied:
- Request written explanation and the name of the airline medical reviewer.
- Ask what documentation would allow travel in the future and whether a MEDIF would change the decision.
- Contact your doctor to obtain the required clearance or arrange alternative transport.
- If you purchased refundable or flexible tickets, ask about rebooking or refunds. If not, check travel insurance for coverage of medical cancellations.
Know your rights and stay calm. Airline customer service and airport medical teams can assist with next steps.
Frequently asked questions
Q: What blood oxygen level is too low to fly?
A: There is no single universal cutoff. Many clinicians use a resting oxygen saturation below about 92 percent on room air as a flag for further evaluation. People with chronic lung disease sometimes have lower baselines. An individualized assessment is essential.
Q: How far in advance should I contact the airline about a medical condition?
A: Contact the airline as soon as travel is planned and at least 48 to 72 hours before departure if a MEDIF or oxygen is needed.
Q: Can I take my own oxygen cylinder on a commercial flight?
A: Most airlines do not allow personal oxygen cylinders in the cabin. Some accept approved portable oxygen concentrators. Always confirm with the airline well in advance.
Q: Is a pregnant person allowed to fly after 36 weeks?
A: Many carriers restrict travel after 36 weeks for single pregnancies and earlier for multiples. A doctor’s note may be required after 28 weeks.
Q: Are children with medical conditions treated differently?
A: Pediatric cases require coordination with the child’s physician and the airline. Young children may also have special oxygen or seating needs. Discuss with the airline and your clinician.
Final steps before you travel
- Get a clear written medical clearance that states the diagnosis, stability, oxygen needs, mobility limitations, and any contingencies.
- Confirm airline medical policies, accepted oxygen devices, and all documentation requirements.
- Bring copies of labs, imaging, and recent discharge summaries in your carry-on.
- Consider travel insurance with medical evacuation coverage if you have significant preexisting conditions.
Knowing the health conditions you should not fly with and the reasons behind them helps you make safer choices. When in doubt, prioritize medical clearance, communicate early with your airline, and choose a medical transport option when commercial flights are not appropriate. Safe travel starts with planning and clear medical advice.
Not Sure if You’re Safe to Fly? We Can Help.
Navigating airline medical forms (MEDIF) and oxygen requirements can be overwhelming during a health crisis. Whether you need a Commercial Medical Escort to assist on a standard flight or a Private Air Ambulance for critical care, Travel Care Air has been moving patients safely since 1980 all over the world.
Contact or call us 24/7 to speak with a flight coordinator.