Dehydration: Symptoms, Causes, Prevention, and Treatment

Dehydration is a physiological state that occurs when the body's output of water and essential mineral salts (electrolytes) exceeds its intake. Water constitutes approximately 60% of an adult's body weight and is critical for cell function, body temperature regulation, joint lubrication, and waste elimination.

When fluid levels drop, the volume of blood circulating in the body decreases, forcing the cardiovascular system to work harder to distribute oxygen. Dehydration also disrupts the balance of key electrolytes—specifically sodium, potassium, and chloride—which are vital for nerve signaling and muscle contraction.

Dehydration is frequently triggered by environmental, behavioral, or illness-related factors, including:

• Inadequate Intake: Failing to drink enough water due to lack of availability, a busy schedule, or a diminished thirst mechanism (common in elderly adults).
• Gastrointestinal Illness: Severe vomiting and watery diarrhea cause rapid, massive losses of fluids and electrolytes within hours.
• Excessive Sweating: Heavy exertion in hot, humid weather without adequate replacement leads to significant water loss.
• Increased Urination: Uncontrolled diabetes or the use of diuretic medications increases urine output.

Dehydration symptoms progress in severity as fluid loss increases:

• Mild to Moderate: Increased thirst, dry or sticky mouth, dark yellow or amber-colored urine, infrequent urination, dry skin, and mild headache.
• Severe: Extreme thirst, lack of sweat production, rapid heart rate and breathing, sunken eyes, low blood pressure, severe dizziness or confusion, and fainting.

Electrolytes are minerals in the blood and body fluids that carry an electric charge. They affect how your body functions, including the amount of water in your body, the acidity of your blood, and your muscle function. When you lose fluid through sweat, vomit, or diarrhea, you also lose these critical minerals. Rehydrating with plain water in large quantities after severe losses can cause a dangerous dilution of sodium in the blood, a condition known as hyponatremia. This is why electrolyte-rich solutions are vital.

For mild-to-moderate dehydration, oral rehydration is highly effective. Drink small, frequent sips of water or Oral Rehydration Solutions (ORS). ORS contains a precise ratio of sodium, potassium, and glucose that optimizes fluid absorption in the small intestine. Avoid sports drinks, sodas, or fruit juices for severe dehydration, as their high sugar concentration can worsen diarrhea and abdominal discomfort.

For severe dehydration, oral fluids are insufficient or unsafe due to lethargy or vomiting. This is a medical emergency that requires immediate hospitalization and intravenous (IV) fluid administration to restore blood volume and electrolyte balance rapidly.

Prevention is key. Drink fluids throughout the day rather than waiting until you feel thirsty, as thirst is a late sign of dehydration. Monitor your urine color—it should be pale straw-colored or clear. Increase your fluid intake during hot weather, physical exercise, or when you are feeling unwell with a fever, vomiting, or diarrhea. Ensure children and elderly family members have constant access to water, as they are at a higher risk of developing dehydration quickly.