Why Do I Always Get Sick After Flying? A Doctor Weighs in on What You Can Do to Stay Healthy.

“Traveling can impose certain stresses on your body [that] can all conspire to make you feel less than stellar at your destination or on getting home,” says Dr. Lawrence Loh, a public health physician and adjunct professor at the Dalla Lana School of Public Health at the University of Toronto.

The occasional travel sickness will hit just about everyone who travels by air at some point. Thankfully, there are a few ways to get around catching something on the plane if you understand what the underlying issues are.

If you’ve ever walked into an airplane feeling completely fine, but have come out of it several hours later with the sensation that you’ve swallowed an entire sheet of coarse-grit sandpaper, you’re not alone. Having a scratchy, sore throat — or even losing your voice entirely — after a long flight is prevalent and can be explained by two things.

1. You’re all dried up

The air in an airplane is entirely renewed every few minutes. It consists of approximately 50 percent recycled air that’s gone through a HEPA filter, and 50 percent air that’s been pulled from outside and treated. While the process ensures the air is clean and safe to breath, it also means it’s very dry. The high-altitude air sucked in from outside and pumped into the aircraft at regular intervals is naturally dry. Think of how dry the air feels in the mountains and tack on tens of thousands of feet in more altitude.

According to the UK Civil Aviation Authority, relative humidity in an airplane cabin ranges between 10 to 20 percent, while it ranges between 40 to 50 percent in a building.

The lack of moisture in the air will dry out your mucous membranes in and around your lips, eyes, nostrils, mouth, and throat. Using lip balm, eye drops, and saline nasal spray can help prevent dryness. Drinking much more water than usual during a flight can help avert a sore throat from being too dried out. Chewing gum is also a good way to produce more saliva and keep your mouth and throat moisturized. Loh also recommends limiting alcohol and salty foods while traveling, both of which can exacerbate dehydration.

To remedy a dry, sore throat, Loh simply recommends lozenges and rehydration.

2. You caught a virus

A sore throat caused by dryness and an infectious sore throat caused by a virus might feel the same at first, but they require different prevention methods and remedies.

“While recirculated cabin air contains filtration to reduce the risk of disease transmission, the proximity to so many other individuals, some of whom might be sick, increases the risk of a respiratory illness which may present with sore throat,” Loh explains.

To prevent a viral infection that might cause a sore throat, Loh suggests a number of measures the general public has become accustomed to since the height of the pandemic:

• Wash your hands regularly
• Use wipes to clean high-touch surfaces around your seat, including your tray table, your video screen, etc.
• Wear a mask during peak respiratory seasons
• Ensure that your respiratory vaccines (flu, covid-19, and RSV) are up to date
• Hydrate with water regularly

A post-flight sore throat is easily resolved with time and adequate hydration, vitamin C, tea with honey, lozenges, and pastilles, Loh says. If you experience pain or fever, he recommends you take ibuprofen or paracetamol. However, if your sore throat lasts more than three to five days and is accompanied by either a fever greater than 101 Fahrenheit, swollen glands, or discharge in the back of the throat, seek the advice of a primary care doctor.

“If the sore throat is caused by something bacterial, such as streptococcus (strep) then you might need to go on a short course of antibiotics,” Loh says.

A sore throat isn’t the only health issue that may arise from a flight. There are multiple ailments and illnesses, ranging from disagreeable to fatal, that can result from spending hours cramped in an airplane. Loh gives us a rundown of the most common ones:

• Dehydration, exhaustion, and gastrointestinal upset: These are common results of not drinking enough water, time changes that lead to a lack of quality sleep, and dietary changes (eating fast food or airplane food instead of one’s normal diet). This can take the form of bloating, dry skin and lips, irregular bowel movements, indigestion, stomach pain, and fatigue.
• Infectious illness, such as respiratory or gastrointestinal illness: These sicknesses can be the result of inoculation due to proximity to other individuals or contact with fomites (stationary surfaces) of an infected individual. Respiratory illnesses such as flu or the common cold can typically present with a cough, runny nose, sore throat, difficulty breathing, and fever. Gastrointestinal illnesses can present with stomach upset, vomiting, and diarrhea.
• Muscle strain: While not in the category of illnesses that people typically think of from flying, muscle strain is common and can result from overexertion, little movement, or sleeping in odd positions. It can present with shooting, intermittent muscular pain; reduced movement in joints or limbs; and fatigue lasting for weeks. It can also make existing muscular pain worse.
• Blood clots: Also known as thromboses, blood clots can arise from immobility and the pooling of blood, which allows it to start to clot up. Long flights are particularly a problem. This can result in sharp pain and loss of circulation in an individual’s limbs, or, if the clot circulates to the lungs as in a pulmonary embolism, it could lead to more serious issues like difficulty breathing, coughing up blood, and potential loss of life.

There are multiple methods to avoid feeling rotten after a long flight. Many were well-known and thoroughly followed in 2020 and 2021 at the height of the COVID-19 pandemic, but they’re useful at all times, and worth remembering while you travel. Loh recommends the following to avoid getting sick while flying:

• Prior to traveling, make sure your vaccines are up to date, especially respiratory vaccines and any vaccines needed for certain destinations, to protect yourself and others from viruses
• Wash your hands regularly
• Bring hand sanitizer and wipes to keep your hands clean when you can’t wash them at a sink, and to keep the area around your seat sanitary
• Consider wearing a mask to prevent respiratory illness, especially when population-wide infection levels are high
• To stay hydrated, have a bottle of water handy and make good use of it, and don’t turn down any water from the crew
• Avoid drastic changes to your diet prior to and during the flight to avoid stomach upsets
• Move your body and stretch your legs regularly, especially on long flights, to avoid muscle strain and, more importantly, thrombosis — don’t be too shy to make your way to the aisle from the window or middle seat
• Avoid excessive alcohol consumption, which is dehydrating

If your seat neighbor’s air vents are on full blast, or if you’re not adequately dressed for the temperature inside the cabin, you’re a little more vulnerable to infections.

“Prolonged periods of excessive cold can suppress one’s immune response,” Loh explains.

The same goes for sleep deprivation, jet lag, and stress, which can leave you fatigued and lead to a general unwell feeling.

That said, this is not how you’re most likely to get sick while flying.

“The primary mechanism by which people get sick is through infections with a microbial pathogen such as a virus or bacteria, which typically occurs due to proximity with other people who might be sick, or inoculation from fomites,” Loh says.

If you’re feeling under the weather but have a flight scheduled, you should absolutely reconsider traveling until you feel better. This might seem like common sense to many, but it turns out that some have no qualms about sharing their germs with the hundreds of people around them in a plane, as this Reddit post shows:

Currently sitting next to patient 0 and patient 0+1
byu/kittykorgi indelta

Dr. Loh explains that people who are sick should try to stay at home, but he also recognizes that some may be obligated to travel while sick. In this case, “they should do their best to prevent spreading their disease to others,” he says. “This would mean wearing a well-fitting mask and washing hands frequently for a respiratory illness like cold, flu, or covid-19, making sure to not share cups or utensils, and frequent hand washing if a gastrointestinal illness.”

Note that airlines, including all the major US airlines, can deny boarding or chuck passengers out of the plane if they are deemed too sick.