Many people confuse the symptoms of dehydration with altitude sickness, but at minimally to moderately high altitudes, dehydration is responsible for more illness than oxygen insufficiency.
Effects of Altitude: Humidity is lower at higher altitudes. Sweat evaporates quickly and you may not realize how much water you are losing through exertion. The lower oxygen levels also make you breathe in and out faster and more deeply, so that you lose more water through respiration. According to the Wilderness Medical Society, you lose water through respiration at high altitude twice as quickly as you do at sea level. High altitude can also make you need to urinate more often and can blunt your thirst response, putting you at even greater risk of dehydration.
Watch for signs of dehydration: Lack of perspiration, dizziness, shortness of breath, nausea, headache, fatigue.
Altitude Sickness has all the signs of dehydration. In addition, altitude sickness signs may include loss of appetite, vomiting, pins and needles, swelling of the hands feet and face. 20% of people develop mild symptoms between 6,300 to 10,000 feet. Serious symptoms do not usually occur until over 12,000 feet. Even then it is not the height that is important, rather the speed in which you ascended to that altitude. Given enough time, your body will adapt to the decrease in oxygen at a specific altitude. This process is known as acclimatization and generally takes one to three days at any given altitude.
It is advisable to carry water with you wherever you go, and to make a point of drinking frequently. You may be as much as a quart low on fluids before you feel thirsty, and this effect can be magnified at high altitudes. For some reason, many people do not feel as thirsty in higher altitudes as they should, so it is important to take the extra care to drink additional fluids.
Drink Water: Stick to water! Coffee, tea, soda, sugary drinks, and even juice can leech additional fluids from your body. Water is the best hydration fluid there is!
Aneto is the highest mountain in the Pyrenees and in Aragon, and Spain's third-highest mountain, reaching a height of 3,404 meters, 11,168 feet. It lies in the Spanish province of Huesca, the northernmost of all three Aragonese provinces.
By Jeff Brown