The elderly and persons who exercise are most at risk of becoming dehydrated.
Dehydration is a state of diminished total body water content due to fluid losses and/or decreased water intake that affects many body functions. Fluid loss can cause fatigue, reduced endurance, lack of coordination, reduced muscle strength, sleepiness and irritability. Failure to anticipate and correct dehydration can have devastating effects, i.e. heat cramps, heat exhaustion and heat stroke. Ensuring adequate fluid intake at all times is the first line of defense against dehydration.
Dehydration is common for certain groups of people.
Elderly Older people are especially prone to dehydration, mostly because they do not drink as much fluid as they should. Prevention may be as simple as setting alarm clocks every half hour to remind the person to drink more water. One should always take in enough water to prevent thirst. Waiting until one is thirsty to drink indicates that the person is already in need of fluid replacement.
Cold water is more refreshing than water that is at room temperature. Coffee, soft drinks containing caffeine and tea have diuretic effects and cause further dehydration. They should be avoided in favor of water or pleasant-tasting non-caffeinated fluids. Many elderly persons do not drink sufficiently because they are afraid of incontinence.
Athletes Sweating is the major protective mechanism for cooling the body. However, sweat cannot evaporate to cool the body properly when the air outside is humid. Thus, individuals who over-exercise in hot, humid weather can become severely dehydrated and overheated as a result. Sweat contains such substances as sodium, chloride, potassium and other electrolytes. Thus, water alone is not as helpful for dehydration of athletes in hot humid places. Sports drinks contain these electrolytes and also contain carbohydrates to help fuel the muscular activity during athletic events.