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Home arrow Health arrow Heart Health arrow Can Dehydration Cause High Blood Pressure? Symptoms and Causes

Can Dehydration Cause High Blood Pressure? Symptoms and Causes

Written by Edibel Quintero, RD
Fact checked by Rosmy Barrios, MD
Last update: October 11, 2023
6 min read 1542 Views 0 Comments
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In most cases, dehydration can cause low blood pressure. However, high blood pressure has also been linked to dehydration. This article discusses the connection between water consumption and blood pressure, the symptoms of dehydration, and how much water you should drink daily.

can dehydration cause high blood pressure

High blood pressure, also known as hypertension, is a common condition that may lead to life-threatening health complications like heart attack, kidney disease, and stroke. Common factors that cause hypertension include a poor diet, dehydration, and a family history of high blood pressure.

Dehydration can cause high blood pressure because it lowers water content and raises sodium. Hence, vasopressin, a hormone responsible for water retention, is released from the pituitary gland. Vasopressin instructs kidneys to reabsorb more water to prevent more loss through urine. When released in high concentrations, it causes blood vessels to constrict, increasing blood pressure.

This article describes the connection between dehydration and hypertension. Our experts also answer if drinking enough water lowers blood pressure and discusses the main causes and symptoms of dehydration. Read on to find answers. 

Can Dehydration Cause High Blood Pressure?

Dehydration can cause high blood pressure because it triggers the release of the antidiuretic hormone (ADH), which, in large quantities, causes blood vessels to constrict, increasing blood pressure.

The antidiuretic hormone (ADH), also known as vasopressin, is the hormone that plays a key role in regulating sodium, kidney functioning, osmotic balance, and blood pressure in the body.

When the body is dehydrated, there is high sodium and low water concentration in the blood. The body counters this concentration to regain osmotic balance, and the brain signals the pituitary gland to produce vasopressin to regain balance.

The antidiuretic hormone then directs the kidneys to reabsorb more water from the bloodstream. This action prevents further water loss from the body through urine, helping maintain normal blood volume and pressure.

However, if the pituitary gland releases the hormone in high concentrations, ADH constricts peripheral blood vessels, increasing the body’s pressure level.

Dehydration and Blood Pressure – Is There a Link?

There is a link between dehydration and blood pressure. Dehydration can lead to either high or low blood pressure. It triggers vasoconstriction (the narrowing of blood vessels), leading to increased blood pressure because it takes more pressure for blood to travel through them. Dehydration also decreases the blood volume, leading to low blood pressure.

Low blood pressure

When you are dehydrated, the water content in your bloodstream is low, and your body has a fluid imbalance. The blood pressure drops due to a low blood volume, causing the body to go into shock because your organs are not receiving the needed oxygen and nutrients.

Shock is a critical state of the body that requires immediate medical attention. It can lead to multiple organ damage and can also be fatal. If you take medication to maintain the blood pressure levels, going without water is very likely to cause changes in blood pressure.

High blood pressure

Dehydration triggers the brain to release the antidiuretic hormone to help the body retain water for use. The antidiuretic hormone can cause blood vessels to constrict when it is released in high concentrations. 

Narrowed blood vessels restrict the blood that flows through them. Therefore, it takes more pressure for the blood to travel through them, causing a spiked pressure reading.

Does Water Lower Blood Pressure?

Drinking water lowers blood pressure by decreasing the concentration of sodium in the bloodstream. The pituitary gland doesn’t release the antidiuretic hormone in large quantities, reducing vasoconstriction and leading to low blood pressure.

Some individuals cannot keep their pressure levels within the normal range, exposing them to risks, such as developing heart disease, kidney failure, and other complications. However, taking control of one’s health is vital in maintaining healthy blood pressure levels.

A healthy nutrition and activity plan is highly recommended by the American College of Cardiology (ACC) and the American Heart Association (AHA). If you are not sure where to start, try one of the best blood pressure management apps.

Symptoms of Dehydration

If you are dehydrated, your body will definitely show you signs, but to avoid all the unpleasant side effects, it is best to sip water throughout the day. The following are the symptoms to look out for when identifying whether you have severe dehydration:

  • Dry mouth and skin
  • Muscle weakness
  • Headache
  • Dizziness
  • Increased body temperature
  • Fatigue
  • Shriveled skin
  • Sunken eyes
  • Extreme thirst
  • Irregular heart rate
  • Confusion

Sometimes, you might not feel chronically dehydrated straight away. Therefore, it is important to drink enough water even if you do not feel thirsty.

Causes of Dehydration

Dehydration occurs when the body loses fluids faster than it can replace them due to sickness, certain occupations, sweating, and age. Some factors that might cause it are explained below:

#1 Sickness

When you become sick, symptoms such as fever, diarrhea, and vomiting mean the body is losing essential fluids and electrolytes before they can be absorbed in the intestines. Vomiting and diarrhea reduce the normal water content in the body, causing dehydration.

Conditions like diabetes can also cause dehydration because the affected individual tends to urinate more. If the person doesn’t drink more water to replenish the water lost through urine, it can lead to dehydration.

#2 A person’s occupation

Firefighters, military personnel, athletes, and casual laborers are more likely to experience dehydration. Such occupations are highly intensive, and people are working their sweat more than in other types of work.

#3 Perspiration

Dehydration caused by perspiration or sweating can occur, especially when performing strenuous activities like running and working out in hot weather. Your body sweats more to cool itself when the internal temperature rises due to exercise or the hot weather.

When a person sweats excessively, the body loses a lot of water, and failure to drink water to replace the lost fluid leads to dehydration.

#4 Age

Children and infants are more likely to be dehydrated because their small bodies are susceptible to even the slightest changes in body fluid concentrations.

Older adults and people who take blood pressure medications and have underlying health conditions may suffer from chronic dehydration because they have low water and blood volume.

How Much Water Should You Drink?

If you are between the ages of 19 and 30, you need to drink about 131 ounces for men and 95 ounces for women. However, water intake varies from person to person, and other factors come into play.

For instance, physically active people need to drink more fluids than those with sedentary lifestyles. Also, living in hot environments means you sweat more to regulate body temperature. Therefore, drinking fluids helps replenish the water lost through sweat.

In the case of sickness, it is easy to become dehydrated because you might be losing fluids through vomiting, diarrhea, and fevers that make you sweat more. Your physician may recommend oral rehydration solutions, but you need to hydrate more either way.

Pregnant and breastfeeding mothers are also encouraged to drink more fluids. Patients with underlying medical conditions such as diabetes should also have a significantly higher water intake.


Can drinking too much water cause high blood pressure?

Drinking too much water doesn’t cause high blood pressure in healthy, young individuals. A healthy person’s body can regulate fluids and electrolytes quickly. However, older adults and individuals with autonomic failure may have increased blood pressure from consuming water excessively.

What is the best drink for high blood pressure?

Water is the best drink for high blood pressure. It helps keep the body hydrated, preventing the body from releasing vasopressin for water retention when one doesn’t drink enough fluids. If you want something else, try drinking fresh fruit and vegetable juices; they also help prevent dehydration.

What do dehydrated veins look like?

Dehydrated veins have a faint appearance and are less prominent due to the decreased volume of blood flowing through them. Dehydration usually causes a reduction in the diameter of the veins. If you hydrate, the veins become dilated and more visible. 

A Word From Our MD

There is a direct correlation between dehydration and blood pressure. If your body cannot regulate blood pressure without medication, you are more likely to experience changes to your blood pressure when dehydrated.

Drinking water every day is the key to a healthy body, including healthy diastolic blood pressure readings. The normal pressure is 120/80mmHg, and anything over that is considered to be elevated blood pressure levels.

Pressure levels between 121/81mmHg and 139/89mmHg indicate a patient is on the verge of developing hypertension, which is 140/90mmHg or more. Hypertension is dangerous; it can lead to heart failure, stroke, aneurysm, and weak and narrowed blood vessels, among other symptoms.

Therefore, individuals must maintain healthy systolic blood pressure readings to prevent falling victim to the above conditions. Staying hydrated, especially if you have unstable blood pressure, could help keep it under control.


It is important to drink water throughout the day. Dehydration can cause high blood pressure because it leads the brain to stimulate ADH release from the pituitary gland, which, in excess, causes vasoconstriction, leading to elevated blood pressure.

Age, sweating, an individual’s occupation, and sickness may contribute to a person becoming dehydrated. One can identify if they are dehydrated by observing symptoms such as dry mouth and skin, dizziness, and confusion.

Written by Edibel Quintero, RD
Edibel Quintero is a medical doctor who graduated in 2013 from the University of Zulia and has been working in her profession since then. She specializes in obesity and nutrition, physical rehabilitation, sports massage and post-operative rehabilitation. Edibel’s goal is to help people live healthier lives by educating them about food, exercise, mental wellness and other lifestyle choices that can improve their quality of life.
The article was fact checked by Rosmy Barrios, MD
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