Symptoms of dehydration: What they are and what to do if you experience them

Dehydration is a common condition that occurs when your body doesn't have enough fluids to function normally.

The condition can be mild, moderate, or severe. Mild dehydration can usually be reversed by consuming more fluids. Moderate cases may require intravenous (IV) fluids to treat. Severe dehydration is a serious medical condition and requires urgent medical attention.

What are the symptoms of mild to moderate dehydration?

Fluids are essential to keep your body healthy. They protect organs and tissues, regulate body temperature, and maintain electrolyte balance. In addition, fluids aid in digestion and help remove waste products in urine, stool, and sweat.

Since the body needs enough fluid to stay healthy, dehydration can make you feel unwell. The symptoms of mild to moderate dehydration in adults and older children include:

• Thirst: The sensation of thirst is usually one of the first signals that your body needs fluid.
• Headache: Dehydration can lead to headaches, though the exact mechanisms are unclear. Some people tend to experience dehydration headaches more than others.
• Dry mouth: Your body produces less saliva when you're dehydrated, so your mouth and tongue may feel dry.
• Less frequent urination: Urination is one way that fluid leaves the body. When you are dehydrated, there is less fluid to be released. In addition, dehydration may cause the kidneys to retain more fluid, also leading to less urination.
• Dark-colored urine: When you are adequately hydrated, your urine has more water and appears lighter in color. When you are dehydrated, your urine is more concentrated and becomes a darker color.
• Dizziness: Dehydration reduces the volume of your blood, lowering your blood pressure. This prevents adequate blood flow to the brain and can lead to feeling lightheaded or dizzy.
• Tiredness or fatigue: When you are dehydrated, your tissues have less of the fluids they need to function, which can leave you feeling tired or fatigued.

Symptoms of mild to moderate dehydration in infants and young children include:

• less frequent urination (fewer than six wet diapers per day in infants)
• few or no tears when crying
• dry mouth
• sunken soft spot (fontanelle) at the top of the head
• playing less than normal.

What are the symptoms of severe dehydration?

Left untreated, dehydration can cause serious complications including heat-related illnesses, kidney problems, and seizures. In extreme cases, dehydration can be fatal.

Symptoms of severe dehydration

Symptoms of severe dehydration in older children and adults include:

• lack of urination
• rapid heartbeat
• rapid breathing
• confusion
• fainting.

Symptoms of severe dehydration in infants and young children include:

• excessive fussiness or sleepiness
• urinating only once or twice per day
• wrinkled skin
• sunken eyes.

If you or your child experience symptoms of severe dehydration, seek immediate medical attention.

What causes dehydration?

You can become dehydrated if you don't drink enough, you lose too much fluid, or both.

You might drink less than you need if you feel sick or nauseated, have limited access to fluids, or don't drink enough fluids when you spend time in the heat or exercise more than usual.

Some ways you might lose too much fluid include:

• Vomiting and diarrhea: Your body can lose large amounts of fluids and electrolytes through vomiting and diarrhea. To make matters worse, vomiting can make it difficult to keep down enough of what you do drink to replace the lost fluids.
• Fever: Having a fever can lead to dehydration through increased sweating.
• Excessive sweat: You lose fluid when you sweat. This is why being out for long periods in high temperatures, or overdoing physical activity in the heat, can increase the risk of dehydration.
• Frequent urination: Certain conditions and medications can increase the frequency of urination and increase dehydration risk. For example, untreated or uncontrolled diabetes increases urine output. So do certain medications, such as diuretics.
• Alcohol: Alcoholic beverages do not hydrate you, so it's important to drink plenty of water when consuming alcohol to avoid dehydration.

Who is at risk of dehydration?

Although anyone can become dehydrated, certain groups of people are at higher risk. These include:

• Infants and toddlers: Babies and young children are more sensitive to small amounts of fluid loss and experience diarrhea and vomiting more frequently than adults. In addition, they can't always tell you when they feel thirsty, and they depend on those around them to provide fluids.
• Older adults: Older adults have a reduced sense of thirst and store less fluid in their bodies, making them more sensitive to fluid loss. They may also have other health conditions that can heighten their risk.
• People with certain medical conditions: Medical conditions such as diabetes and kidney disease can cause you to sweat or urinate more, increasing the risk of dehydration. People who take diuretics or other medications that increase urine output are also at greater risk.

In addition, certain activities, such as exercise or working outdoors in the heat, can increase the risk of dehydration.

Dehydration treatment

Dehydration is treated by replacing the fluid that has been lost. In older children and adults, mild to moderate dehydration can be treated by increasing fluid intake. When rehydrating:

• Go slow and take small sips.
• Try ice cubes or popsicles.
• Dilute fruit juices with water so they don't cause an upset stomach.
• Avoid drinks that can make you more dehydrated, such as alcohol or drinks with caffeine.

If you are unable to adequately replace fluids on your own, you may need to see a doctor.

When to see a doctor

Although mild to moderate dehydration can usually be treated at home, moderate to severe dehydration may require medical treatment, such as receiving fluids through an IV. Talk to your doctor if you aren't sure of the severity of your symptoms.

If you think your infant or toddler might be dehydrated, call your pediatrician right away. In some cases, young children can rehydrate at home, but it is important notify your doctor and follow their instructions.

Dehydration prevention

In many cases, dehydration can be prevented by consuming enough fluids and foods with high water content, such as fruits and vegetables. To the extent possible, avoid being outside for long periods in the heat, and bring outdoor workouts indoors when temperatures climb.

Staying hydrated can be tricky when you're sick, particularly when experiencing vomiting and diarrhea. Switching to a diet of clear liquids and replacing lost fluids and electrolytes with sports drinks can help.