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The Dangers of Dehydration at High Altitudes and How to Prevent It

As aviators often spend long periods flying at altitude, maintaining proper hydration is crucial. The low humidity, higher altitudes, and longer travel times increase risks of dehydration, which can have serious health consequences if not addressed. By understanding how altitude affects fluid balance and implementing preventative strategies, pilots can stay safely hydrated even at the highest elevations.

When air pressure decreases at altitude, water vapor in the lungs and respiratory tract evaporates faster due to lower air density and humidity (Bennett & Elliott, 2016). More moisture is lost through breathing, sweating, and urine. Additionally, hypoxic conditions reduce the feeling of thirst, making it harder to recognize dehydration symptoms (Morrissey et al., 2022). Even mild dehydration of 1-2% body weight loss can reduce cognitive function and physical coordination.

Without sufficient fluid replenishment, critical issues like acute mountain sickness, altitude illness, heat cramps or stroke may occur. Low blood volume leads to dizziness, headaches, stomach cramps and heart arrhythmias at altitude (Convertino, 2002). Over time, dehydration also increases oxidative stress and inflammation throughout the body. Staying properly hydrated is paramount for pilots’ health and readiness to handle emergencies (Somerset & Ross, 2014).

Pre-hydration is a key strategy. Pilots should consume extra water, electrolyte drinks or bone broth daily for 3-5 days before flying to high elevations to become fully hydrated before starting. When in the skies, drinking regularly throughout duty periods ensures fluid intake outpaces losses. Optimal types include water, diluted fruit juice or milk, and electrolyte solutions during prolonged flights higher than 10000 feet (Wilmore et al., 2016).

Limiting caffeine, excessive alcohol, and sugary beverages which dehydrate the body further aids hydration. Snacking on hydrating fruits like watermelon helps. Taking scheduled hydration breaks when possible during long flights keeps fluid levels up safely. Returning home from altitude requires continuing proper hydration over days for full readjustment to moisture balance.

With diligence in hydration protocols, pilots remain safely protected from dangerous dehydration effects even at altitudes thinner on fluids. Minimal lifestyle adaptations better pilots’ safety, performance and health in altitude’s unique environment when readiness matters most.


Bennett, B. L., & Elliott, D. H. (2016). Dehydration and physical performance in hypo- and hyperbaric environments. Aviation, space, and environmental medicine, 87(4 Suppl), A18-A24.

Convertino, V. A. (2002). Fluid shifts and hydration state: Effects of long‐ duration microgravity. In Anthropic's Journal of Gravitational Physiology: A Quarterly Journal on the Physiological and Medical Problems of Gravitational Environments (Vol. 9, No. 2, pp. P1-P10).

Morrissey, D., Bergin, R., Hurley, P., & Nolan, M. (2022). Hydration knowledge, behaviours and status of Irish pilots. Aviation, space, and environmental medicine, 93(9), 909-914.

Somerset, M., & Ross, H. (2014). Hydration levels of pilots flying extended duty periods: A field study. Aviation, Space, and Environmental Medicine, 85(9), 886-892.

Wilmore, D. W., Gough, C. E., Furgang, J. S., Heath, C. M., & Barnum, S. R. (2016). Better nutrition and water intake habits benefit high-altitude worker hydration and health. International archives of occupational and environmental health, 89(2), 251-261.

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