10 Signs of Severe Dehydration: Symptoms You Shouldn’t Ignore

Your body needs water to work properly. Water helps control your body temperature, keeps your organs working, and carries nutrients throughout your body.

If you lose too much fluid and don’t replace it, you can become dehydrated. Mild dehydration can often be treated by drinking fluids. Severe dehydration is a medical emergency and needs immediate care.

Knowing the warning signs can help you get treatment before serious problems develop.

What Is Severe Dehydration?

Severe dehydration happens when your body loses more water and electrolytes than it takes in.

Without enough fluids, your heart, kidneys, brain, and other organs cannot work the way they should.

If it isn’t treated, severe dehydration can lead to:

• Shock
• Kidney failure
• Seizures
• Organ damage
• Death

10 Warning Signs of Severe Dehydration

1. Extreme thirst

Feeling very thirsty is often one of the first signs.

You may notice:

• Dry mouth
• Dry lips
• Feeling thirsty even after drinking water

Older adults may not always feel thirsty, even when they are dehydrated.

2. Dark urine or very little urine

Urine color is one of the easiest ways to check your hydration.

Healthy urine is usually pale yellow.

Severe dehydration may cause:

• Dark yellow, amber, or brown urine
• Very little urine
• Not urinating for several hours

3. Dry mouth and dry skin

Your body makes less moisture when you’re dehydrated.

Signs include:

• Dry mouth
• Cracked lips
• Dry tongue
• Dry skin
• Skin that doesn’t quickly return to normal after being gently pinched

4. Dizziness or feeling lightheaded

When you don’t have enough fluids, your blood pressure can drop.

You may feel:

• Dizzy
• Weak
• Unsteady
• Like you might faint

5. Fast heartbeat

Your heart has to work harder when your body doesn’t have enough fluids.

You may notice:

• A racing heartbeat
• Heart pounding
• Fast pulse, even while resting

6. Confusion or trouble thinking clearly

Severe dehydration can affect your brain.

Symptoms include:

• Confusion
• Trouble concentrating
• Memory problems
• Irritability

In older adults, confusion may be one of the first signs of dehydration.

7. Extreme tiredness or weakness

Feeling unusually tired is common with dehydration.

You may have:

• Very low energy
• Heavy arms and legs
• Muscle weakness
• Trouble doing normal daily activities

8. Sunken eyes

Fluid loss can make the eyes appear sunken.

This is especially common in:

• Babies
• Young children
• Older adults

9. Low blood pressure

Losing too much fluid lowers the amount of blood your heart can pump.

Symptoms include:

• Feeling faint
• Blurred vision
• Cold hands and feet
• Weak pulse

10. Fainting

Passing out is one of the most serious signs of dehydration.

If someone faints because of dehydration, get emergency medical care right away.

Who Is Most at Risk?

Anyone can become dehydrated, but some people are at higher risk.

This includes:

• Babies and young children
• Adults age 65 and older
• People with vomiting or diarrhea
• People with a fever
• Athletes
• Outdoor workers
• People with diabetes
• People taking water pills (diuretics)
• People with kidney disease

Hot weather also increases the risk.

Mild vs. Severe Dehydration

Mild Dehydration	Severe Dehydration
Thirst	Extreme thirst
Dry mouth	Very dry mouth and cracked lips
Mild tiredness	Extreme weakness
Light yellow urine	Dark urine or very little urine
Mild dizziness	Severe dizziness or fainting
Normal heart rate	Fast heartbeat
Can usually be treated by drinking fluids	Needs medical care right away

When Should You Go to the Emergency Room?

Get emergency medical care if you have:

• Fainting
• Confusion
• Trouble staying awake
• Very little or no urine
• A fast heartbeat
• Severe dizziness
• Repeated vomiting
• Bloody diarrhea
• Cold, clammy skin
• Trouble breathing

Severe dehydration often needs IV fluids and electrolyte replacement.

How to Prevent Dehydration

You can lower your risk by:

• Drinking water throughout the day
• Drinking more fluids when it’s hot outside
• Replacing fluids after vomiting or diarrhea
• Eating fruits and vegetables with lots of water, like watermelon, oranges, cucumbers, and strawberries
• Replacing electrolytes after long periods of exercise
• Limiting alcohol
• Checking that your urine stays light yellow

Frequently Asked Questions

Get Care at Grady

If you or someone you love has signs of dehydration, don’t wait. Early treatment can help prevent serious complications.

Call 911 or go to the nearest emergency department right away if you have confusion, fainting, trouble staying awake, severe dizziness, or signs of shock.

For ongoing concerns about dehydration or frequent illness, call (404) 616-1000 or schedule an appointment online. Grady’s primary care providers can evaluate your symptoms, find the cause, and connect you with the care you need.