Dehydration in Adults Overview

Dehydration is a condition that can occur when the loss of body fluids, mostly water, exceeds the amount that is taken in. With dehydration, more water is moving out of individual cells and then out of the body than the amount of water that is taken in through drinking. Medically, dehydration usually means a person has lost enough fluid so that the body begins to lose its ability to function normally and then begins to produce symptoms related to the fluid loss. Although infants and children are at highest risk for dehydration, many adults and especially the elderly have significant risk factors.

People (and animals) lose water every day in the form of water vapor in the breath we exhale, and as water in our sweat, urine, and stool. Along with the water, small amounts of salts or electrolytes are also lost. Our bodies are constantly readjusting the balance between water (and salts or electrolytes) losses with fluid intake. When we lose too much water, our bodies may become out of balance or dehydrated. Most doctors divide dehydration into three stages: 1) mild, 2) moderate and 3) severe. Mild and often even moderate dehydration can be reversed or put back in balance by oral intake of fluids that contain electrolytes (or salts) that are lost during activity. If unrecognized and untreated, some instances of moderate and severe dehydration can lead to death. This article is designed to discuss dehydration in adults.

Causes of Dehydration in Adults

Many conditions may cause rapid and continued fluid losses and lead to dehydration.

• Fever, heat exposure, too much exercise, or work-related activity
• Vomiting, diarrhea, and increased urination due to infection
• Diseases such as diabetes
• The inability to seek appropriate water and food (an infant or disabled person, for example)
• An impaired ability to drink (someone in a coma or on a respirator, or a sick infant who cannot suck on a bottle are common examples)
• No access to safe drinking water
• Significant injuries to skin, such as burns or mouth sores, severe skin diseases, or infections (water is lost through the damaged skin)

In addition to drinking water, the body also needs replacement of electrolytes (for example, potassium and sodium) lost with the above mentioned conditions, so drinking water without electrolyte replacement may not complete the balance of water and electrolytes the body has lost. Some symptoms (see below) may remain if this balance is not restored.

Symptoms and Signs of Dehydration in Adults

The signs and symptoms of dehydration in adults range from minor to severe.

Mild to moderate dehydration may include the following:

• Increased thirst
• Dry mouth
• Tired or sleepy
• Decreased urine output
• Urine is low volume and more yellowish than normal
• Headache
• Dry skin
• Dizziness
• Few or no tears

The above symptoms may quickly worsen and indicate severe dehydration with signs and symptoms are developing; severe dehydration may include the following:

• Severely decreased urine output or no urine output. The urine, if any, produced is concentrated and a deep yellow or amber color.
• Dizziness or lightheadedness that does not allow the person to stand or walk normally.
• Blood pressure drops when the person tries to stand after lying down (low blood pressure or orthostatic hypotension)
• Rapid heart rate
• Fever
• Poor skin elasticity (skin slowly sinks back to its normal position when pinched)
• Lethargy, confusion, or coma
• Seizure
• Shock