What are some health conditions that can prevent flying?

Certain acute, unstable, or contagious health conditions can temporarily or permanently prevent you from flying safely.

Contagious and Infectious Diseases

• Active, highly contagious illnesses like COVID-19, influenza, chickenpox, measles, or tuberculosis prevent you from boarding commercial flights to protect other passengers.
• Airlines and public health guidelines require you to wait until you are past the active, infectious window or obtain an official fit-to-fly certificate.

Cardiovascular and Circulation Issues

• Recent heart attacks or unstable angina make flying dangerous due to lower cabin oxygen levels and travel-related stress.
• Deep vein thrombosis (DVT) or active blood clots restrict air travel until evaluated and managed with treatments like blood thinners, since prolonged sitting increases clot risks.
• Uncontrolled high blood pressure can lead to cardiac strain or severe symptoms during a stressful travel day.

Respiratory Conditions

• A collapsed lung (pneumothorax) or conditions involving trapped air pose severe risks because barometric pressure changes at altitude cause trapped gases to expand.
• Severe chronic obstructive pulmonary disease (COPD) or severe asthma with ongoing breathing distress or oxygen dependence requires special airline medical clearance and pre-arranged in-cabin oxygen.

Recent Surgeries and Injuries

• Recent major surgeries—especially involving the abdomen, brain, eye, or cardiovascular system—require a mandatory waiting period (often 1 to 3 weeks or more) because cabin pressure changes and altitude affect healing tissues and trapped gas.
• A wired jaw for a fractured mandible is restricted by most airlines unless a specialized release device or wire-cutter setup is prepared for emergencies.
• Recent eye surgery involving gas bubbles prevents flying until the gas is completely reabsorbed, as altitude changes cause the bubble to expand and damage the eye.

Neurological and Mental Health Conditions

• Recent strokes generally require a grounding period of 2 weeks to 3 months depending on severity and doctor evaluation.
• Poorly controlled epilepsy or severe seizure disorders can be aggravated by altitude hypoxia, dehydration, and sleep disruption.
• Unstable severe psychiatric disorders that risk unpredictable, confused, or aggressive behavior onboard make flying unsafe for both the passenger and the flight crew.

Pregnancy and Early Infancy

• Advanced pregnancy past 36 weeks (or past 32 weeks for multiple pregnancies) is restricted by most commercial airlines without explicit medical clearance.
• Newborn infants under 48 hours old are typically prohibited from flying, and infants under 7 days often require medical forms.

You should avoid flying with acute, unstable, or contagious medical conditions because reduced cabin oxygen and pressure changes can make them dangerous.

Heart and Circulatory Conditions

• Recent heart attack: Wait at least two to three weeks, or longer for complicated cases, before flying.
• Unstable angina: Avoid flying if you experience chest pain while at rest or with minimal exertion.
• Uncontrolled high blood pressure: Get your blood pressure stable and well-controlled before boarding.
• Active deep vein thrombosis (DVT) or pulmonary embolism: Do not fly with a fresh blood clot until treatment is finished and a doctor approves.

Lung and Respiratory Conditions

• Collapsed lung (pneumothorax): Do not fly until a chest X-ray confirms full recovery and clearance is given (usually waiting 1 to 2 weeks).
• Severe COPD or asthma: Avoid flying if you have severe breathing issues or require high levels of continuous supplemental oxygen.
• Pneumonia: Postpone travel if you have an active, moderate-to-severe infection with breathing difficulties or fever.

Infectious Diseases

• Contagious illnesses: Stay home if you have the flu, chickenpox, measles, active tuberculosis, or COVID-19 to avoid spreading germs in a closed cabin.

Recent Surgeries and Injuries

• Recent abdominal or chest surgery: Most airlines and doctors advise waiting at least 10 days to 2 weeks due to trapped gas expansion and healing risks.
• Recent eye or brain surgery: Pressure shifts can harm healing tissues; consult your surgeon before booking.
• Decompression sickness: Anyone suffering from "the bends" after deep-sea diving must not fly.

Pregnancy and Other Issues

• Late-term pregnancy: Most commercial airlines restrict travel past 36 weeks of pregnancy (or 32 weeks for multiples).
• Uncontrolled epilepsy: Frequent or severe uncontrolled seizures make air travel unsafe without medical precautions.

You can read more about managing health risks during long flights in this guide to health risks of long-haul flights.

Certain acute, unstable, or contagious medical conditions can temporarily or permanently prevent you from flying safely on commercial airlines.

Heart and Circulation Conditions

• Recent heart attack or stroke: Airlines usually require a waiting period (often 2 weeks to 3 months) depending on severity.
• Unstable angina: Chest pain at rest makes air travel dangerous due to lower cabin oxygen levels.
• Deep vein thrombosis (DVT): Active or unmanaged blood clots restrict travel until treated.
• Severe, uncontrolled high blood pressure: High risk of stroke or cardiac strain during travel.

Lung and Respiratory Conditions

• Untreated pneumothorax: A collapsed lung traps air that expands with cabin pressure changes.
• Severe COPD or oxygen dependence: Low oxygen saturation at cruising altitude can cause severe hypoxia.
• Active respiratory infections: Severe pneumonia or flu-like illnesses risk both your health and other passengers.

Infectious and Contagious Diseases

• Active childhood diseases: Conditions like chickenpox, measles, or mumps bar you from boarding until non-contagious or scabs fall off.

Surgery and Trapped Gas Conditions

• Recent surgeries: Especially abdominal, thoracic, brain, or eye surgeries where trapped gas or unhealed incisions risk rupture from pressure shifts.

Pregnancy

• Late-term pregnancy: Most airlines restrict flying after 36 or 37 weeks for a single pregnancy, or 32 weeks for multiples.

Mental Health

• Unstable psychiatric conditions: Active psychosis, severe unmanaged anxiety, or risk of behavioral disruption in a confined space.

Note: For official rules on professional pilot licensing restrictions, consult the Federal Aviation Administration guidelines.

Doctors may tell you not to fly when changes in cabin pressure or lower oxygen levels at high altitude can make an existing health problem worse.

Heart and Circulation

• Recent heart attack or stroke: Doctors usually advise waiting at least two weeks or longer depending on recovery.
• Unstable angina: Chest pain that happens even when you are resting.
• Uncontrolled high blood pressure: Severe hypertension that is not managed with medicine.
• Deep vein thrombosis (DVT): Recent blood clots in the legs, which can be worsened by sitting still for a long time.

Lungs and Breathing

• Collapsed lung (pneumothorax): Air trapped in the chest cavity can expand as cabin pressure changes.
• Severe COPD or asthma: Conditions where breathing is difficult or blood oxygen levels are already low.
• Active lung infections: Pneumonia or other serious breathing infections.

Recent Surgery or Injury

• Major chest or abdominal surgery: Trapped air or gas inside the body can expand and cause severe pain or injury within 10 days of the procedure.
• Recent eye surgery: Procedures that use gas bubbles inside the eye can be dangerous because the gas expands at altitude.
• Severe head injury: Increased pressure inside the skull.

Contagious and Other Conditions

• Active infectious diseases: Flu, chickenpox, measles, or COVID-19 pose a risk to other passengers in a closed cabin.
• Severe anemia: Very low red blood cell counts reduce the blood's ability to carry oxygen.
• Advanced pregnancy: Many airlines restrict flying after 36 weeks for a single pregnancy or 32 weeks for multiples.
• Severe ear or sinus infections: Pressure changes can cause extreme pain or damage the eardrum.

For more details on how specific health issues interact with travel, see the Merck Manual Guide to Travel and Health. If you need guidance for an upcoming trip, review advice on managing medical conditions before flying.

Airlines generally restrict passengers with unstable, contagious, or severe medical conditions that can be worsened by cabin pressure changes and low oxygen levels.

Cardiovascular Conditions

• Unstable angina: Chest pain that occurs at rest or is getting worse.
• Recent heart attacks: Usually prohibited within 7 to 14 days of an uncomplicated heart attack (or up to 4–6 weeks for complicated cases).
• Uncontrolled heart failure: Severe shortness of breath or fluid buildup.
• Unmanaged high blood pressure: Extremely high resting blood pressure readings.

Respiratory Conditions

• Active pneumothorax: A collapsed lung is an absolute contraindication until fully healed and cleared by a doctor.
• Severe COPD or asthma: Patients who experience constant breathlessness at rest or require high oxygen flow that standard cabin environments cannot support.
• Active pneumonia: Uncontrolled infections accompanied by fever and breathing difficulties.

Contagious and Infectious Diseases

• Active viral/bacterial infections: Conditions like chickenpox, measles, mumps, or active tuberculosis while still in a contagious or feverish stage.

Surgical and Physical Constraints

• Recent surgeries: Travel is typically restricted for 10 to 14 days following major chest, brain, or abdominal operations.
• Eye surgery with gas bubbles: Retinal procedures involving intraocular gas require waiting until the bubble completely disappears, as cabin altitude changes cause the gas to expand.
• Severe anemia: Hemoglobin levels typically dropping below 7.5 to 8.5 g/dL.
• Decompression sickness: Passengers recently returning from deep-sea scuba diving ("the bends").

Neurological and Behavioral Issues

• Uncontrolled epilepsy: Flying should be avoided for 24 hours after a seizure, and those with frequent, unmanaged seizures need clearance.
• Disruptive behavior: Any patient with unpredictable, aggressive, or severe psychiatric instability that poses a safety risk to the flight.