Given the high cost of changing plane tickets, many people fly even if they’re sick. But there are times when you should delay your trip—or abort takeoff altogether—because of medical complications that can result from the decreased air pressure and oxygen in a plane, along with other physiological stresses of flying. If you have any medical conditions, you should at least get medical advice beforehand to be sure that you’re fit to fly.
Some airlines may require a medical certificate from your doctor stating that it’s safe for you to fly if you have a medical condition or contagious disease that could lead to an in-flight illness or injury or significant risk to fellow passengers. If you use supplemental oxygen, the airline will likely require a medical certificate. However, airline policies vary—and some airlines charge a fee to supply in-flight oxygen—so check with your carrier before booking a ticket.
The following examples are basic guidelines for common conditions. Consult with your doctor at least one month before traveling if you’ve had any recent surgery, injury, or illness; have had or are at risk for blood clots; or have an unstable or chronic condition (especially if heart- or lung-related).
If you have a cardiovascular condition
Though recommendations vary depending on the individual, flying is generally not advised for about two weeks after a heart attack (longer if there were complications) or bypass surgery. If you have a recent electrocardiogram, carry a copy of it with you.
If you have an implantable cardioverter defibrillator or a pacemaker, remember to bring your related wallet identification card.
Avoid flying if you have unstable angina, uncontrolled high blood pressure, or other cardiac problems that aren’t well controlled.
If you have lung disease
Conditions such as chronic obstructive pulmonary disease or asthma can make it difficult to breathe in an airplane cabin, where oxygen levels are lower than normal, even if you don’t use supplemental oxygen at home.
Some patients with unstable disease, such as individuals who are breathless at rest, can fly with supplemental oxygen, though others, such as those with active pneumonia or unresolved pneumothorax (a collapsed lung), should not fly at all.
If you have a neurological condition
If you’ve recently had a stroke, you generally shouldn’t travel until your condition has stabilized for at least two to four weeks, but your doctor should assess your ability to fly safely. People with frequent transient ischemic attacks shouldn’t fly because of the risk of stroke during a flight.
If you have epilepsy that’s controlled, you can generally fly safely. However, if you have frequent, uncontrolled seizures (one or more in the previous month), you should avoid flying.
If you get migraines, carry rescue medications with you since airline travel can sometimes trigger headaches.
If you’re at increased risk of deep vein thrombosis
A personal or family history of blood clots or obesity, menopausal hormone therapy use, recent surgery, cancer, and limited mobility are some factors that put you at risk of an in-flight blood clot in a deep vein in the leg. Consult your doctor about ways to minimize your risk, such as taking frequent walks up and down the aisle.
If you’re anemic
Your doctor may suggest supplemental oxygen if your hemoglobin level is below 8.5 grams/deciliter so you don’t become light-headed or lose consciousness while flying.
After surgery or other procedures
You should typically wait 10 to 14 days after major surgery to allow air introduced into the body during the procedure to reabsorb. Otherwise, trapped gases, which expand as you ascend, can tear sutures, damage tissues, and cause bleeding.
Certain eye procedures, such as retinal detachment surgery, require a waiting period anywhere from a few days to eight weeks.
Wait 24 hours after a colonoscopy to fly because of the gases introduced during the procedure. Likewise with a laparoscopic (minimally invasive) procedure—wait 24 hours before flying.
If you have an ear infection, a sinus infection, or another upper respiratory tract infection
The Eustachian tube, which runs between the upper throat area and the middle ear, helps equalize air pressure between the middle ear and outside the ears. If the tube is swollen or blocked, as can occur with some infections, descending in an airplane (and to a lesser extent ascending) can cause sharp pain, dizziness, and even bleeding and rupture of the eardrum.
If you have a severe middle ear infection, an active sinus infection, nasal polyps, or recent nasal surgery, you shouldn’t travel by air. If in doubt, see an ear, nose, and throat specialist to clear you for flying.
If you have a mild infection such as a cold, taking an oral decongestant two hours before flying and using a nasal decongestant like Afrin 30 minutes before takeoff should help. On longer flights, use the nasal decongestant 30 minutes before landing.
If you have a contagious disease, such as influenza or the measles
You should wait until you are no longer contagious—for your comfort and to protect passengers nearby.
If you have a fracture
Wearing a cast could be a problem because the limb may swell, causing discomfort and even impingement of circulation and nerves. Bivalved casts, which are cut on both sides and can be opened like a clamshell, are recommended for recent fractures (less than 48 hours).
Your best bet is to check with your doctor before flying with a fracture—and ask the airline what their rules are.
First published February 2015; updated March 2020. This article also appeared in the March 2020 issue of UC Berkeley Health After 50.
Also see How to Unclog Your Ears on a Plane.