The perception that air travel increases the risk of catching a cold is a common concern for travelers. While modern aircraft utilize sophisticated air filtration systems, the unique environment of the cabin, combined with the stress of travel, creates specific challenges for the body’s natural defenses. Understanding the mechanisms that make the body more susceptible to infection during a flight allows travelers to employ a layered approach using supplements and physical barriers for prevention.
Why Flying Increases Cold Risk
The primary environmental factor contributing to vulnerability is the extremely low humidity level inside the airplane cabin. Cabin humidity often falls below 20%, significantly lower than the comfortable indoor range of 30% to 60%. This dry air rapidly dehydrates the mucosal membranes lining the nose and throat.
The drying effect compromises the mucociliary clearance system, the body’s natural mechanism for trapping and expelling airborne pathogens and irritants. When this protective layer dries out, the delicate cilia slow down, making it easier for viruses to penetrate the respiratory tract. Close proximity to many people in an enclosed space increases the likelihood of exposure to respiratory droplets. Furthermore, the physical and psychological stress of travel, including disrupted sleep and jet lag, can temporarily suppress immune function, making the body less effective at fighting off viruses.
Immune-Boosting Supplements to Consider
Addressing the physical and biological stresses of flying often involves supporting the immune system internally with targeted supplements. Zinc is a popular choice because of its role in immune function, with some research suggesting it may interfere with the replication and binding of the rhinovirus, the most common cause of the common cold. While zinc does not reliably prevent the onset of a cold, taking it orally, often in lozenge form, may modestly shorten the duration of symptoms if a cold does occur. Adults should keep the maximum daily intake below 40 milligrams, and it is important to avoid intranasal zinc products, which have been associated with permanent loss of smell.
Vitamin C is highly utilized, though its ability to prevent a cold for the average person is largely considered a myth. Taking a daily dose of 1,000 to 2,000 milligrams may slightly reduce the duration of cold symptoms, especially if the regimen is started before the flight and maintained regularly. A pronounced preventative effect is only consistently observed in individuals undergoing brief periods of extreme physical stress, such as marathon runners.
Vitamin D plays a broad role in immune support and is a factor in fighting off respiratory infections. Many people already have suboptimal Vitamin D levels, so ensuring an optimal baseline before travel is advisable. Some experts suggest temporarily doubling the usual dose before, during, and immediately after a trip. Probiotics may also offer support, as a large portion of the immune system resides in the gut, and daily supplementation has been linked to a reduced susceptibility to upper respiratory tract infections.
Physical Barriers and Hygiene Practices
Beyond internal supplements, physical barriers and meticulous hygiene practices are actionable steps to mitigate risk during air travel. A simple yet effective measure to counter the dry cabin air is the use of a saline nasal spray. A non-medicated saline solution moisturizes the nasal passages, supporting the integrity of the mucosal barrier and its ability to filter airborne particles. The spray can be used before boarding, periodically during the flight, and after landing to rehydrate and flush out irritants.
Wearing a high-filtration face mask, such as an N95 or KN95 respirator, provides a physical barrier against inhaled respiratory droplets. Although aircraft use HEPA filters, the mask offers immediate protection against particles released by nearby passengers before the air is fully filtered. For maximum effectiveness, the mask must be worn correctly, ensuring a tight seal over the mouth and nose.
Frequent hand hygiene is a foundational defense, as many viruses transfer from contaminated surfaces to the face. Travelers should use an alcohol-based hand sanitizer after touching high-contact surfaces like tray tables and armrests. Wiping down the immediate seating area with an antibacterial wipe upon boarding is a proactive step. Avoiding touching the face, especially the eyes, nose, and mouth, minimizes the chance of transferring pathogens.