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The Link Between Dehydration and Blood Pressure

Jun 14, 2024

Editors note: Original publish date: Feb 3, 2024 – Updated on June 1, 2024

Water is essential for human life. Dehydration is a common condition that occurs when there isn’t enough fluid in the body. Low body water can be caused by not drinking enough fluids or by losing fluids from the body faster than they can be replaced.

Dehydration may cause other conditions, such as low or high blood pressure, and can further complicate existing medical conditions, such as kidney disease.

Key Points

Dehydration Overview

Dehydration is a condition that describes the absence of enough water in the body. It is reported that 75% of the adult American population is chronically dehydrated.

The human body is made up of at least 78% water. The muscles and kidneys are 79% water, while the heart is 73% water.

Water has an essential role in:

  • Regulating body temperature
  • Aiding in digestion and removing waste products
  • Balancing the body’s chemicals
  • Lubricating the joints and cushioning the bones
  • Producing saliva
  • Delivering oxygen throughout the body
  • Acting as a shock absorber for the brain, spinal cord, and fetus if you’re pregnant

When you don’t consume enough water, or your body loses water too quickly through sweating, diarrhea, and vomiting, you can become dehydrated. Other causes of dehydration include:

  • Certain medications, such as diuretics
  • Water loss from the skin due to fever, burns, heat, exercise, severe skin diseases
  • Failure to replace lost fluids
  • Not drinking enough daily water or fluids
  • Urinating too much due to illness or certain medications

Anyone can become dehydrated, but children and infants are at an increased risk as they may be unable to tell anyone they are thirsty; this is especially true for sick children.

Signs and symptoms of dehydration in adults:

  • Headache
  • Constipation
  • Loss of appetite
  • Muscle cramps
  • Low blood pressure (hypotension) with a high heart rate
  • Dark-colored urine that has a strong smell

Complications of severe dehydration can include:

  • Kidney complications, such as kidney failure and kidney stones
  • Electrolyte imbalances
  • Heatstroke and other heart-related conditions
  • Shock, coma, and even fatality

Mild dehydration can be treated by drinking more water and by mixing oral rehydration packets with your water. Moderate dehydration treatment requires an IV drip, where fluids are added to your body through the vein. Severe hydration requires emergency treatment.

Blood Pressure Overview

Blood pressure is the force of blood on the artery walls. Each time the heart beats, it pumps oxygen-rich blood into the arteries. The arteries then carry the oxygen and nutrient-rich blood from the heart to the rest of the body. Blood pressure typically rises and falls throughout the day.
High blood pressure typically does not have any symptoms, but it is a significant risk factor for diseases such as cardiovascular disease. Chronic high blood pressure is often called the “silent killer” as, without warning, it can damage the heart, brain, and kidneys.

Without treatment, high blood pressure can cause:

  • Kidney disease
  • Stroke
  • Heart attack
  • Aneurysms

Low blood pressure occurs when there is a decrease in blood volume, and blood is not able to move around the body to tissues and organs efficiently. Very low blood pressure, or hypotension, is typically considered a problem when symptoms present, such as:

  • Fainting
  • Blurred vision
  • Confusion
  • Lightheadedness or dizziness
  • Fatigue
  • Heart palpitations

Complications of hypotension can include shock, heart conditions or stroke, and injuries from falling due to fainting or dizziness.

Blood Pressure and pulse

Both pulse (heart rate) and blood pressure involve the heart. However, they are two different things. Pulse (heart rate) is the number of times that the heart beats per minute, while blood pressure is the force that blood travels through the arteries.

An increase in pulse does not mean that the blood pressure has increased. The only way to determine blood pressure is to measure it with a blood pressure cuff and gauge.

How Does Dehydration Affect Blood Pressure and Pulse?

Dehydration and blood pressure

As the blood in the body is made up of mostly water, dehydration can lead to changes in blood pressure, causing both high and low blood pressure. The loss of fluid in the body (hypohydration), including blood volume, can lead to low blood pressure. This means that the body, its organs, and tissues may not get the oxygen and nutrients needed to function correctly.

When blood pressure drops to low levels, the body has mechanisms in place to stabilize blood pressure levels. In some cases, the body can overcorrect.

Dehydration typically raises sodium levels in the blood. The body responds by releasing a hormone called vasopressin, which stimulates the body to retain water. High concentrations of vasopressin also cause the blood vessels to constrict or become narrower, resulting in rising blood pressure. This rise in blood pressure can become a concern for people with hypertension.

Dehydration and pulse

Dehydration strains the heart as the blood volume circulating through the body decreases. The heart compensates for the low blood volume by beating faster, and the heart rate (pulse) increases.

Can Dehydration and Blood Pressure Affect the Kidneys?

Dehydration can affect the kidneys. This is because water helps the kidneys remove waste products from the blood via the urine. Water also plays a role in keeping the blood vessels open so that nutrient-dense blood can flow into the kidneys.

If someone becomes dehydrated, the lack of water makes it more difficult for this system to work properly. Mild dehydration starts to impair normal body functions, while severe dehydration can result in the kidneys becoming damaged.

Dehydration causes waste products and toxins to build up in the body, placing additional strain and damaging the kidneys. Dehydration can also increase the risk of urinary tract infections (UTIs) and the formation of kidney stones. If not treated appropriately, both these conditions can lead to kidney damage.

How Much Water Should You Consume Everyday?

Consuming enough water and other fluids every day is the most effective way to avoid blood pressure and pulse issues related to hydration.

The National Academies of Science, Engineering and Medicine recommends the following baseline for total daily water (water in food and liquids) intake:

91 ounces (2.7 liters) for women
125 ounces (3.7 liters) for men

Factors such as prolonged physical activity and climate may require increasing total water intake.

Panoramic Health

Panoramic Health is an integrated provider group delivering the future of kidney care. Our mission is to improve patients’ outcomes by slowing disease progression and improving their quality of life. We do this through the distinctive capabilities of our comprehensive care model, which brings together an integrated provider group with operational support, clinical support, and data & analytics at scale.

Through partnerships with practices, providers, payers, and health systems, we work to advance the usage of clinically validated best practices and cutting-edge data analytics across a continuum of reimbursement models.

*The content presented in this article is for informational use only and should not be construed as medical advice or replace the medical advice of a qualified physician.