Dehydration: Meaning, Signs and Symptoms, Causes and Prevention

Key takeaways

• Dehydration occurs when we lose more body water than we replenish.
• Some major signs and symptoms of dehydration include thirst, deep-colored yellow urine, headaches, and oral dryness. 
• Dehydration can affect anyone, regardless of age and gender.
• Kidney stones, constipation, colorectal cancer, and precancerous polyps are some of the complications that can arise from chronic dehydration. 

The human body and its fluids are primarily composed of water. An average adult weighing 70kg is about 60% water. Some organs, like the brain, kidneys, skin, and lungs, contain even higher percentages of water. 

The total water content in the human body varies with age and weight, which can affect how much water an individual requires. For example, infants have a substantially higher water content, often around 75% of their body weight, which drops to about 65% by one year of age. 

On the other hand, older adults typically have around 50–60% water content, with men generally having a slightly higher percentage than women due to body composition.

Water is essential for maintaining cell function, health, and survival. When not taken in an adequate amount, it could lead to dehydration, which disrupts these vital processes and can lead to a decline in cell function and overall health. 

What is dehydration?

Dehydration is a common health condition that affects people globally. It occurs when the body loses excessive water or moisture, and the lost fluids aren’t replenished well enough for the body to function properly. In simpler terms, dehydration occurs when the body loses more fluids than it takes in.

The human body eliminates water through various organs daily. The skin expels water as sweat, the lungs release water vapor during breathing, the kidneys filter excess water into urine, and even stool contains some water that gets eliminated.

Signs and symptoms of dehydration

Here are some general signs and symptoms of dehydration in adults and children under five years:

• Thirst
• Strong-smelling, dark yellow urine
• Urinating less than usual
• Headaches or lightheadedness
• Fatigue or feeling tired
• Feeling of dryness in skin, lips, mouth, and tongue
• Heavy/sunken eyes

Symptoms of dehydration in infant babies under six months include:

• A sunken soft spot (fontanelle) on top of their head
• Heavy/sunken eyes
• Little or no tears during cries
• Consistent few wet diapers 
• Drowsiness or irritability. 
• Weak pulse 
• Fatigue 
• Cold or moist extremities

Studies show that little children and elderly patients are more susceptible to suffering from severe dehydration. Little children can suffer dehydration due to their lack of communication skills, hindering their ability to request water when thirsty.

Elderly patients, on the other hand, are prone to suffer dehydration, partly due to changes in their water and sodium balance and the gradual deterioration of their thirst sensation, which occurs naturally as people age.

Causes of dehydration

Dehydration occurs when your body loses more water than you take in. Here are some factors or conditions that may trigger this process: 

1. Inadequate water intake

Dehydration occurs when you don’t replace fluids lost throughout the day. This may disrupt your body’s physiological balance and can lead to health problems. 

Daily water needs vary based on age, climate, and activity level. However, health practitioners recommend about 2.7–3.7 liters (12–16 cups) to stay properly hydrated. This can be adjusted for people who consume other hydrating fluids like beverages, fruits, and vegetables.

2. Diarrhea

Diarrhea is another common cause of dehydration. Gastrointestinal infections, like diarrhea, can cause severe dehydration, especially when it is long-lasting or severe. Frequent watery stools lead to loss of fluids and electrolytes, putting the body at risk.

3. Vomiting

Another very common cause of dehydration is vomiting. Vomiting expels fluids and electrolytes like bicarbonate, sodium, potassium, and chloride, not just from your stomach but also from your upper digestive tract. This ongoing fluid loss can lead to dehydration and even mild electrolyte imbalances.

4. Increased urination

Frequent urination (polyuria) can cause dehydration if you don’t replace the fluids lost. It may also be a symptom of underlying health problems, such as diabetes, high blood pressure, or urinary tract infections. This shows dehydration may arise as an associated symptom of polyuria.

5. Excessive sweating

Excessive sweating can lead to significant loss of body water, especially during hot weather or while engaging in intensive physical activities like running, cycling, or high-intensity workouts.

Complications from dehydration

If left unresolved, certain complications may arise from constant dehydration. A study published by the University of Arkansas suggests that chronic dehydration can be linked to health complications like:

• Kidney stones
• Constipation
• Colorectal cancer
• Precancerous polyps
• Bladder cancer

Other effects of short-term dehydration may include:  

• Poor cognitive skills,
• Impaired ability to focus on tasks
• Urinary tract infections 
• Mood swings.

Chronic dehydration can also affect saliva production, which may contribute to an increased risk of dental caries (tooth decay) over time.

Tips for preventing dehydration

To avoid the deleterious effects of dehydration, here are some helpful tips to keep you properly hydrated: 

• Drink water even before you feel thirsty. 
• To add variety to your fluids, you can include unsweetened tea, fruit juice, and flavored sparkling water (with minimal added sugars or sodium).
• Carry a portable water bottle during the day and refill it when needed.
• Drink water often, especially with meals.
• Always drink water before, during, and after exercise.
• Be sure to drink extra fluids during hot weather and when you fall sick.

Seeking medical attention for dehydration

If you experience persistent dehydration symptoms, consult a doctor to rule out any underlying conditions. They can accurately diagnose your situation and ensure you receive the proper treatment.

For mild to moderate dehydration, your doctor might recommend oral rehydration solutions (ORS). These ORS come in pre-measured powders or liquids mixed with water to create a drink. They contain electrolytes, like sodium, potassium, chloride, and glucose (sugar), to help your body absorb fluids more effectively and replenish lost minerals.