Water is essential for nearly every system in the body

But if tiredness occurs alongside thirst, darker urine, and reduced urination, dehydration may be contributing.

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4. Headaches Can Appear

Not drinking enough fluids may contribute to headaches in some people.

Headache is a recognized symptom of mild to moderate dehydration, although the exact reason can vary.

A headache can also have many unrelated causes, including lack of sleep, stress, migraine, illness, caffeine withdrawal, eye strain, and other factors.

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If you develop a persistent, severe, or unusual headache, don’t automatically assume dehydration is responsible. Drinking fluids may help if dehydration is contributing, but ongoing or severe symptoms deserve medical attention.

5. You May Become Dizzy or Lightheaded

Dehydration can reduce the amount of fluid circulating through your body.

When fluid loss becomes significant, blood pressure may fall. Some people may especially notice dizziness or lightheadedness when standing up.

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Possible symptoms include:

• Dizziness

• Lightheadedness

• Feeling faint

• Unsteadiness

Severe dehydration can cause a significant drop in blood pressure and requires prompt medical attention.

If dizziness is severe, repeatedly occurs, or is accompanied by fainting, chest pain, trouble breathing, confusion, or other neurological symptoms, seek medical care rather than assuming you simply need more water.

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6. Your Heart May Beat Faster

As dehydration becomes more significant, the cardiovascular system may have to work harder to maintain adequate circulation.

More serious fluid loss can be associated with:

• A rapid heartbeat

• Low blood pressure

• Rapid breathing

• Weakness or severe fatigue

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A faster heart rate does not automatically mean dehydration is the cause. Exercise, anxiety, fever, medications, anemia, heart problems, and many other conditions can also increase heart rate.

If you experience an unexplained racing heartbeat, particularly with chest pain, shortness of breath, fainting, or severe weakness, seek urgent medical attention.

7. Your Muscles May Cramp

Fluids and electrolytes both play important roles in normal muscle function.

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People who lose substantial amounts of fluid through heavy sweating, vomiting, or diarrhea may develop muscle cramps or weakness.