Dehydration can happen at high altitudes, in cold weather climates and during travel. It can also lead to heat exhaustion and heat stroke, a life-threatening condition. If you are a traveler or an adventurer, it’s important to know how to stay hydrated and how to recognize dehydration symptoms.

Dehydration doesn’t just happen when you are exercising in hot weather (77 degrees Fahrenheit or higher). It can also happen at high altitudes, in cold weather climates, while traveling, and during short periods of physical activity.

Dehydration is defined as an excessive loss of body water. When this happens, according to the Mayo Clinic, your body doesn’t have enough fluid to carry out normal body functions. Dehydration can occur when you don’t drink enough, have a fever, sweat excessively or if you are ill (vomiting and diarrhea cause a large water loss in a short amount of time).

[Related Reading: The Heat Is On: Get Ready For Summer Travel]

What Are the Signs of Dehydration?

Dehydration symptoms may be immediate — or they can sneak up on you.

“The most obvious symptoms are urinating less frequently and, when you urinate, it may be less volume and dark in color,” said Dave Keaveny, a paramedic and senior specialist in the Medical Operations Department at Global Rescue. “‘Clear and copious’ is the phrase used by many outdoor schools to identify the target sign of adequate hydration.”

The signs of dehydration in adults include:

  • Thirst
  • Headache
  • Dizziness
  • Tiredness
  • Confusion
  • Irritability
  • Dry mouth/nose/skin
  • Increased heart rate
  • Increased respiratory rate
  • Decreased blood pressure
  • Sunken eyes, pale skin
  • Loss of skin elasticity
  • Fainting
  • Muscle cramps

Symptoms will be more profound in younger children, especially infants. Watch out for no tears when crying, no wet diapers for three hours, and increased irritability or tiredness, to name a few.

“Seniors are more susceptible to dehydration and most are dehydrated due to lifestyle, certain medical conditions and polypharmacy, the use of multiple drugs,” Keaveny said.

What Should You Do If You Are Dehydrated?

  • Halt physical activity
  • Seek shade and cool (or warmth/shelter if winter)
  • Sip water, the best drink for hydration
  • Eat some light snacks

When Should You Get Medical Help?

“When your body is in a state of volume depletion, your cardiac system has to work harder to maintain cardiac output and homeostasis, or optimal functioning,” Keaveny said. “This can cause a variety of issues and symptoms.”

Get medical help if you are experiencing:

  • Weakness
  • Dizziness
  • Confusion
  • Fainting
  • Chest pain/pressure/palpitations
  • Shortness of breath
  • Elevated body temperature
  • Altered mental status

In fact, just a couple of hours of vigorous activity in the heat without drinking fluids or eating can greatly affect concentration, according to the Georgia Institute of Technology in Atlanta. The study showed when the participants lost more water, they increasingly made more errors during attention-related tasks.

Does Altitude Affect Hydration?

“Yes. Your kidneys are working harder to help your body compensate for the altitude, and you are likely exerting yourself. This increases urine production,” Keaveny said.

In addition, you’ll also be losing water from your body through respiration and sweat. The relative humidity is generally lower at altitude and the solar exposure is more intense.

It happened to one Global Rescue member on his ascent of Makalu, the fifth highest mountain in the world (27,838 feet/8,485 meters). He was experiencing fever, mild headache and diarrhea, and called Global Rescue for a field rescue. At the hospital, he was given oral and IV fluids for his diagnosis: acute diarrhea with dehydration.

Does Travel Affect Hydration?

The air on aircraft has extremely low humidity levels. The air at high altitudes is almost completely devoid of moisture and about 50% of the air circulating the cabin is pulled from the outside.

This dry air is only part of the problem. Most people don’t drink enough water when they are at home, let alone on travel days.

“They never give you enough water on planes. The small bottles of water or 4-ounce cups of water are not enough for the average person,” Keaveny said. “When you get up and stretch, ask for extra water. The airline will usually provide one if you ask.”

In addition, you could be drinking alcohol and caffeine, which are dehydrating. They are considered to be diuretics, meaning they cause fluids to pass through your body more quickly.


Hydration Tips from Travel Experts

Before you set out on any adventure, a travel health consultation is always a good idea.

“Certain medical conditions or medications can contribute to dehydration and heat illness,” Keaveny said. “Consult your doctor prior to travel or certain activities.”

  • Anticipate by staying hydrated the day before. Start your day with two cups of water and end your day with another two cups.
  • During the activity, drink to thirst, avoiding excessive hydration.
  • Eat sweet or salty snacks every 45 minutes for an electrolyte boost. Electrolytes are important for body function, and dehydration creates an imbalance of electrolytes. “Replacing and maintaining electrolytes is just as important as replacing and maintaining hydration,” Keaveny said. “Make sure you are not overhydrating and washing out important electrolytes.”
  • When traveling, bring a collapsible water bottle to fill after going through security. During the flight, drink at least 8 ounces of water per hour. Research shows the conditions of an airplane can lead to 1.5 to 2 liters (6 to 8 cups) of water loss in a 10-hour flight, despite water intake.
  • Wear glasses instead of contacts on the plane to help prevent discomfort to the eyes. Pack small bottles of lotion, eye drops or nasal spray if you’re worried about drying out.
  • After the sport or activity, replace fluids and calories lost. Oral rehydration salts or sports drinks may not be safe for all patients, especially the elderly. Consult your doctor prior to travel.

Is Dehydration Fatal?

Heat exhaustion — a result of dehydration and heat stress — includes (but is not limited to) the following symptoms: headache, fatigue, dizziness, nausea/vomiting, abdominal cramps, pale or clammy skin, increased heart and/or respiratory rate. Keaveny recommends immediately removing the person from the hot environment; providing fluids, oral rehydration salts or sports drinks; and offering salty-sweet snacks as tolerated.

Without prompt treatment, heat exhaustion can lead to heatstroke, a life-threatening condition that happens when the body’s temperature rises rapidly, the sweating mechanism fails, and the body is unable to cool down. According to the CDC, the body temperature can rise to 106°F or higher within 10 to 15 minutes.

Heatstroke has all the symptoms of heat exhaustion plus these hallmark signs:

  • Change in behavior/mental status
  • Nervous system disturbance, such as tremors
  • Elevated temperature
  • Skin can either be red, warm and dry — or pale, cool and clammy

“Heat exhaustion leads to heat stroke, which is a true medical emergency,” Keaveny said. “Call local EMS immediately, remove the person from the hot environment, and provide oral fluids as tolerated.”