Traveling while sick is not anyone’s favorite past-time. But, sometimes you absolutely have to. Maybe you can’t miss that meeting or postponing your flight would mean having to miss an important event. Sometimes it isn’t financially possible to reschedule your trip, especially since airlines are quite reluctant to give refunds (or even partial credit) unless it’s for a true emergency.

While it’s certainly not advisable, some illnesses are minor enough that you can fly under the radar. But some maladies can be exacerbated by the rigors of travel, making you much sicker than you were to begin with. And then there’s also the fact that some sicknesses are highly contagious and could impact hundreds of other passengers, particularly the young, elderly and those with compromised immune systems. If you’re truly on the fence about how sick you may be, how can you tell if you’re too sick to safely travel? We’re here to give you some general guidelines that will help you assess whether you should wing it or start calling the airline to reschedule your travel plans.

When shouldn’t you fly?

If you have a fever above 100 degrees…

Fevers are a rule breaker for flights. A mild fever isn’t cause for alarm, but anything over 100 degrees should have you calling the airline pronto. This is a sign of an infection that could be transmitted to others or even worsen during travel, making you miserable by the time you land.

If you’re experiencing chest pain or having difficulty breathing…

Please call your doctor first and worry about your flight second. Chest pain or breathing difficulties could be signs of serious, life-threatening conditions and shouldn’t be taken lightly. Your flight should be postponed until after you get a thorough check-up from your doctor.

If you’re feeling queasy…

Queasiness could just be a symptom of nervousness, or it could be the onset of a stomach bug or food poisoning. If you feel otherwise healthy, it’s probably safe to travel, but if you have any of these other symptoms, you should definitely postpone your flight: chills, fever, sore throat, stomach cramps or diarrhea.

If you’re having sinus problems or have an earache…

The pressure in the cabin could make these problems considerably worse, so be very cautious if you’re experiencing pain. Flying with an ear infection can be very dangerous. Your eardrum could rupture if the cabin pressure isn’t stabilized properly, and that could lead to permanent hearing loss.

What if you choose to fly anyway?

Prepare yourself for a few hours of feeling under the weather. Pack plenty of water, tissues, antibiotic wipes, pain/fever relievers and wear comfy clothes. Purchase nasal decongestant spray and use it about 30 minutes before takeoff to reduce swelling, if needed, and stock up on gum to keep your ears equalized. You can also purchase special pressure-regulating earplugs that are beneficial if you’re suffering from an earache and you’re worried about possible ruptures. And as always when traveling, try to be considerate of others, especially when you’re sick. Minimize your exposure to other passengers by snagging an empty row if the plane isn’t filled to capacity. If it is, try to get a seat in the first few aisles so you don’t have to walk past all of the other passengers on the plane to get to your seat.

What if you have to cancel your flight?

Try to give as much notice as possible. If you call 24 hours or more before your flight, your airline may be able to switch it at no extra charge or cancel it entirely for only a small fee as opposed to losing the whole cost of the flight. Before you call, look up the cancellation policy that you received when you made your reservation so you’re aware of the rules and what you’re entitled to in your particular situation. Even if you’re airline doesn’t issue refunds for illness according to their rules, it still may be beneficial to call and speak to an airline representative. They’ll sometimes review refund requests on a case-by-case basis, so you may just get lucky and be able to postpone your flight a few days. And nothing beats being proactive in life. The next time you book a trip, (especially if you’ll be traveling during flu season) purchase the insurance to alleviate any worries about cancellations.