Can Dehydration Affect Your Blood Pressure?

Because of the high intake of caffeinated drinks, alcohol, and a diet packed with sodium, people are struggling with chronic dehydration.

In fact, 75% of Americans have chronic dehydration. Depriving the body of fluids activates thirst response, causing irritability, memory fog, and poor cognitive function.

The older population is 20% to 30% more likely to become dehydrated. Health problems such as renal illnesses, diabetes, immobility, and impaired thirst mechanism make them prone to experiencing inadequate fluid intake.

When left unmanaged, it can have serious consequences, like kidney disease. Many people want to know does drinking water lower blood pressure, including whether fluid deprivation can cause drastic blood pressure fluctuations. 

This guide provides a detailed analysis of the impact of fluids on the blood. Here is all you need to know about hydration before your next blood pressure reading. 

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Dehydration and Hypertension

Chronically dehydrated patients are prone to high blood pressure. Their body cells can’t get enough fluids to function properly, which hinders the signaling pathways and affects the pituitary gland. The gland ends up secreting vasopressin, a chemical responsible for constricting the blood vessel. 

That’s why people experience high blood pressure and the possibility of hypertension. Observational reports link regular low water intake with higher chances of cardiovascular disease and complications. 

The longer the person avoids drinking water, the bigger the risk for poor blood pressure regulation and impaired vascular function. Therefore, anyone with blood pressure problems, including secondary hypertension, should watch their water and salt intake. 

In dehydrated obese individuals, this can become a pressing issue. The lack of fluid in the blood leads to increased calcium concentrations. When that person also has immobility, the bones can’t handle the weight and emit more calcium into the blood. 

Did you know: Low fluid intake can also have a drastic impact on a child’s health. A child that struggles with dehydration from an early age can develop high blood pressure later in life.

Research suggests that a small percentage of children who didn’t drink enough water during infancy required medical treatment for high blood pressure when they turned 7. They experienced much higher blood pressure levels than their peers, which predisposed them to possible health complications. 

Another controlled trial revealed that limiting the sodium intake in the first 6 months of the child’s life was linked to low blood pressure at the age of 15. But, more conclusive data is necessary to explain the connection between blood pressure and early life dehydration. 

Dehydration and Hypotension

For many, lower blood pressure seems desirable. It doesn’t cause that much discomfort and health complications. But, for patients who regularly struggle with extremely low blood pressure, it becomes challenging to deal with all the fainting and dizziness. 

Dehydration is one of the many reasons that could cause hypotension. Systolic blood pressure puts a serious strain on the heart. In fact, systolic pressure and diastolic pressure are equally important. They help monitor heart health

People with heart failure are typically hospitalized for being dehydrated. Since patients experience a reduction in blood volume, dehydration makes it difficult to maintain a stable blood pressure level. 

The blood volume (also known as plasma volume) is the fluid that circulates in the blood vessels scattered across the body. For the system to maintain a healthy plasma volume, the blood must get to all the tissues in the body. If you don’t drink water, the volume reduces, causing a sudden drop in blood pressure known as orthostatic hypotension.

The lower the pressure, the harder it becomes for the blood to function properly, which ends up failing to supply the organs with the necessary nutrients and oxygen. With this kind of blockage in the artery, people can be at risk of heart disease, heart attack, and unstable heart rate. 

Thus, water is critical for ensuring ideal heart health. That’s why it is crucial to educate everyone on the importance of recognizing the signs of poor fluid intake. 


People can develop a wide assortment of symptoms. To figure out when someone is dehydrated, it is vital to learn to recognize these red flags. These signs are often linked, but not limited to:

  • Dry lips and skin

  • Extreme thirst

  • Fatigue

  • Low urine output

  • Dark urine

  • Headaches

  • Muscle cramps

  • Dizziness

  • Heart palpitations

  • Weakness

  • Appetite changes

Children display similar signs. But when you want to recognize them during infancy, take a look at the following symptoms below:

  • Irritability

  • Not wetting the diapers for a couple of hours

  • Lack of tears when crying

  • Sunken eyes and cheeks

  • Soft spot on the skull

  • No enthusiasm, energy, and interest

What’s the Ideal Water Intake a Day? 

Around 20% of the fluid you take will come from the food you eat. What’s important is that both children and adults supply their bodies with the necessary healthy fluid intake. To replenish the water supply, and avoid these signs, you would need plenty of water.

The recommended intake is:

  • For women: 2.7l (11.5 cups) on a daily basis.

  • For men: 3.7l (15.5 cups) on a daily basis. 

  • For children (age 4 to 13): 6 to 8 glasses of water on a daily basis. 

Note: Younger children need smaller servings, such as 250 ml for an older child and 150 ml glass for a 4-year old child.  

Some people may not realize that they are losing water through fecal fluid, skin, respiration, and urinary output. So, determining the exact number of fluid intake can be a little difficult. Under normal circumstances, in healthy individuals who do regular physical activity and eat nutritious food, 500 ml of fluids a day will be excreted. 

Studies show that the ideal fluid intake a day should be around 2,200 ml for women and 3,000 ml for men. Even if they drink more than that, they could prevent recurrent kidney stones. 

Other Ways to Improve Fluid Intake

Your diet can also have a negative impact on hydration, especially if you eat meals high in sodium, sugar, caffeine, or protein. While the calcium in hard water can lead to digestive problems. To skip the calcium and contamination, opt for purified water. 

To get the desired results, start with healthy lifestyle changes. Change your diet and implement more water-rich foods such as cucumber, oranges, pomegranate juice, beet juice, etc. With a healthy diet and a healthy weight, you can go a long way. Unhealthy dietary fat, like saturated fat, can cause weight gain.

Besides, depriving the body of fluids can put a lot of pressure on your weight loss process. If you plan to stick to a Mediterranean diet or dash diet, know that eating water-rich foods and skipping the extra sodium is still essential for the blood. For the kidneys, eat more potassium and magnesium. 

Just pay attention to all those risk factors when you want to avoid getting dehydrated. Another option is salinated water. It has multiple uses, one of which is to help with dehydration. These are all practical options for healthy blood pressure in dehydrated individuals. 

When Is the Right Time to Ask for Medical Treatment?

If you’ve been struggling with poor fluid intake for a long time, you can have multiple signs that need medical attention. These signs include:

  • Bloody/black stool

  • Extreme confusion, fatigue, and disorientation

  • Quickened heartbeat

  • Diarrhea that persists for over 24h

But, make sure to pay attention to the blood as well. Blood sugar can result in various health problems that may need medical intervention. 

For Hypotension

Lower blood pressure than normal doesn’t often cause any serious issues. But, when the low readings are paired with one of the following signs, then it’s a good idea to get your blood locked at. These warning signs are:

  • Blurry vision

  • Extreme exhaustion

  • Dizziness

  • Lightheadedness

  • Nausea

  • Clammy or cold skin

  • Shallow or quickened breathing

For Hypertension

People on blood pressure medication can have increased blood pressure. But, it is difficult to pin-point the exact signs. The elevated levels are usually found on a routine checkup. So, to ensure optimal health, it is better to do regular readings or consult with your doctor on how to manage the blood pressure or high blood sugar level


When the body is deprived of fluids, people can experience sudden fluctuations in blood pressure. The poor plasma volume makes it difficult for the blood to reach the organs and keep the system in tip-top shape. Both high and decreased blood pressure is associated with poor water intake. But, more large-scale studies are necessary to evaluate its full impact on blood flow and the human body.  


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  2. Joseph C. Watso. (2019). Hydration Status and Cardiovascular Function. National Institutes of Health. Retrieved from:
  3. George Davey Smith. (2006). Could dehydration in infancy lead to high blood pressure. National Institutes of Health. Retrieved from:
  4. Elizabeth B. Jones. (2020). Adult Dehydration. National Institutes of Health. Retrieved from:
  5. Dr. Frankie Phillips. How much water should your child drink a day. Retrieved from:
  6. Arend-Jan Meinders. (2010). How much water do we really need to drink. National Library of Medicine. Retrieved from:
  7. Lawrence E. Armstrong. (2018). Water Intake, Water Balance, and the Elusive Daily Water Requirement. National Institutes of Health. Retrieved from:

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