Although there are a variety of altitude hazards to your health and many ways to prevent and cure - especially by knowledge and good commonsense - there is one single important health tip that can help you avoid all sorts of health problems…..it can completely alter your performance in trekking/climbing as well as your ability to acclimatize and deal with altitude. It is very simple yet crucial – it is the drinking of water.
Simple as that. Drink. Drink, Drink! Staying hydrated equips you to acclimatize, exercise better, fight off hypothermia and frostbite, constipation, diarrhea….so plan to drink a minimum of 3 liters per day at rest, add more as needed for exertion and other losses (eg if you are working hard and sweating you may need up to 8 liters, or if you are ill with vomiting or diarrhea and losing lots of fluids, you will need to replace those losses too.) One or two hours before trekking/climbing, try to drink 1-2 liters to “fill your tank” -- some find that they continue to drink more while active if they use an easily accessible hydration hose system (an example of a commercial system – Camelback – these prevent the hassle of reaching for a bottle – the hose is right next to your mouth!)
The best way to check that you are well hydrated is to check your urine. You need to drink until it’s clear and straw colored. Deep yellow/amber urine color usually means you are concentrating and need more water. If you aren’t waking up at least once at night to urinate at altitude, you probably aren’t drinking enough.
Finally - remember that coffee, tea and chocolate contain caffeine, which is a diuretic and won’t do the work well. Count in only 50% liquid value with these.