How to tell when you’re too sick to fly

Flu and cold seasons are officially upon us — complicating the worsening coronavirus pandemic.

In the past, you may have shrugged off mild symptoms like a sniffly nose or a tickle in your throat. But now, you can't board an airplane without certifying you don't have any symptoms of COVID-19, including a fever of 100.4 degrees or higher, shortness of breath or difficulty breathing, a cough and more.

Beyond what the airlines may specify, travelers should watch for a laundry list of symptoms specified by the U.S. Centers for Disease Control and Prevention (CDC), which can appear between two and 14 days after exposure to the virus that causes COVID-19:

• Fever or chills
• Cough
• Shortness of breath or difficulty breathing
• Fatigue
• Muscle or body aches
• Headache
• New loss of taste or smell
• Sore throat
• Congestion or runny nose
• Nausea or vomiting
• Diarrhea

Travelers need to be extremely mindful about even the most innocuous ailments now, as they could be an indication of COVID-19. But, even in normal times — or if the coronavirus isn't detected by a COVID-19 test — it's important to prioritize your health and the health of others. Here's why you should never board a flight if you're feeling sick.

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You have a fever

A good rule of thumb is to never fly when you have a fever, according to New York-based internist Dr. Frank Contacessa.

In addition to indicating a possible COVID-19 infection, a fever could also present itself if you have the flu.

“Having a fever, in general, will accelerate fluid loss from your body," Dr. Contacessa told TPG in 2019. "The very low humidity of the cabin air will dehydrate you even faster. Dehydration makes you feel even worse, increasing weakness, headaches, lightheadedness, etc.”

You’re vomiting

Sure, there might be vomit bags in the seatback pocket. But if you're throwing up before you get to the airport, it's a clear indication you need to delay your travels.

“If you have a fever over 100.4 degrees or are experiencing vomiting, there’s a really good chance that you’re contagious,” Dr. Nate Favini, medical lead at Forward (a membership-based preventive care clinic), told TPG in 2019.

Related: It's flu season — here's how to avoid getting sick on a plane

You're short of breath

“The pressurized cabin air has less oxygen, which can make you feel short of breath if your airways are already inflamed from an infection,” said Dr. Contacessa.

Dr. Favini added, “Flying is stressful on your body and your immune system in particular, so it can reduce your ability to fight off an infection. The air onboard is incredibly dry, and even healthy people end up extremely dehydrated at the end of their flight. You may end up being sicker or sick for longer because of flying while ill.”

You could still be contagious

Back in 2019, before the coronavirus was a known threat, Dr. Favini told TPG that travelers experiencing any flu-like symptoms — including fever, cough, runny nose, congestion, nausea, vomiting or diarrhea — are still contagious.

Even if it's not the coronavirus making you ill, you can still infect someone up to 6 feet away.

Related: How to boost your immune system so you don’t get sick while traveling

You have ear pain

Something as minor as ear pain might also be reason enough to avoid flying. You know how your ears sometimes pop during taking off or landing? Well, if you have ear pain and pressure, then that brief moment of discomfort can become severe.

“The changes in pressure during the flight can cause your eardrum to burst if you have an ear infection and it’s not properly treated before you take off,” said Dr. Favini.

Your heart is racing

Even if you don’t have the sniffles or more obvious symptoms of being sick, there is one tell-tale warning sign that you absolutely shouldn't fly. If you do, you could experience a serious medical emergency.

“If you’re experiencing chest pain or a racing heartbeat, especially if this is new or severe, don’t get on your flight,” said Dr. Favini. “This can be a sign of a life-threatening medical condition, and even if the pilot does land your flight, it might not be fast enough for you to get the help you need. The same goes for shortness of breath.”

Related: The best travel insurance policies and providers

When you can fly again

OK, let's say you’ve determined you’re too sick to fly. When can you reschedule your trip?

“If you do change your plans and postpone your trip, you should wait until you have been without a fever for at least 24 to 48 hours,” said Dr. Contacessa back in 2019.

And, of course, if you've been diagnosed with COVID-19, most airlines will ask you to delay travel for at least 14 days after testing positive. Some will require even a longer period of time since your diagnosis.

The CDC says you can be around others 10 days after symptoms first appear and 24 hours without a fever, and any other symptoms have improved.

Additional reporting by Melanie Lieberman.