High Blood Pressure And Hydration

What is high blood pressure?

According to the American Heart Association (AHA), blood pressure is referred to as the force that the blood exerts against the walls of the arteries as the heart pumps blood throughout the body (AHA).1 The blood pressure is written as two numbers in which the first (systolic) number indicates the pressure in blood vessels when the heart contracts or beats, and the second (diastolic) number indicates the pressure in the vessels when the heart rests between beats.2 When the pressure in arteries is higher than normal, it leads to a disease known as high blood pressure, also called hypertension. High blood pressure is diagnosed when the systolic blood pressure readings measured on two different days read ≥140 mmHg and/or, the diastolic blood pressure readings are ≥90 mmHg on both days.2 High blood pressure can lead to health problems, such as heart disease, stroke, kidney failure, vision loss and more if left treated. According to the World Health Organization, about 1.28 billion adults aged 30-79 years have hypertension globally, and about 46% of adults are unaware that they have the condition. 2

Elevated 120-129AndLESS THAN 80
High Blood Pressure (Hypertension)Stage 1 130-139Or80-89
High Blood Pressure (Hypertension)Stage 2 140 OR HIGHEROr90 OR HIGHER
Hypertensive Crisis(Consult your doctor immediately)HIGHER THAN 180And/orHIGHER THAN 120

Water is crucial in regulating blood pressure

Drinking water is good and healthy for the human body. Water is the principal component of the human body, and it’s made up of about 50% and 70% of the body weight.3 This shows that every part of the body is made up of water to function properly. It performs functions such as getting rid of waste, regulating temperature, lubricating and cushioning joints and protecting sensitive tissues. Heart health and blood pressure are also impacted by drinking water. Research has shown that water increases the activity of the sympathetic (fight-or-flight) nervous system, thereby making subjects feel more alert, giving a temporary energy boost and regulating blood pressure.4 This shows that water impacts heart health and blood pressure. Therefore, it's important to drink an adequate amount of water to keep your body hydrated and functioning properly because water improves cardiovascular health. For some people, plain water is good, others may prefer water to be infused with cucumber, lemon, lime, and berries, among other healthy options, if the need for a boost for taste is desired. To stay properly hydrated, we’re encouraged to drink water throughout the day. Specifically:

  • Women should take approximately 11 cups (2.7 litres or about 91 ounces) daily fluid intake which includes all beverages and foods that contain water.
  • Men should take approximately 15.5 cups (3.7 litres or about 125 ounces) of total daily fluid intake which includes all beverages and foods that contain water.

Water can assist in lubricating the body, reducing the risk of conditions like kidney stones and urinary tract infections, helping in improving brain function as well as lowering blood pressure. Generally, drinking eight 8-ounce cups of water is recommended daily. Also, water is contained in food such as fruits and vegetables.

What happens to blood pressure when you’re dehydrated?

The loss of more fluid and electrolytes by the human body than it takes in is known as dehydration. This means that you are not getting the appropriate ratio of electrolytes and enough water needed by the body. This can impact blood pressure negatively. By the time you notice feeling thirsty, you’re probably already dehydrated

Increased vasopressin

Vasopressin, also known as the anti-diuretic hormone, is the hormone that controls the amount of water and electrolytes in the body by regulating kidney function. It acts by regulating and balancing the amount of water in your blood. During dehydration, vasopressin is released by the brain and causes the blood vessels to narrow. This hinders the movement of blood through the blood vessels.6

Kidneys retain water

The kidneys release a substance called renin that causes you to retain more water as a response to dehydration in response to the body’s demand. However, in a chronically dehydrated situation, it can lead to high blood pressure or hypertension.7

Less blood volume causes the blood pressure to rise

The blood becomes thicker as a result of dehydration. This will require more force to move your blood through the blood vessels. The volume of your blood will be decreased, and blood will not adequately reach all the body tissues. This leads to a compensatory rise in blood pressure, often leading to hypertension.7


Dehydration can result in long-term health implications for your organs and other life-threatening situations when left untreated. Also, people with underlying medical conditions can have compilations due to the effect of dehydration on blood pressure. Therefore, proper hydration is essential to ensure you have good health and prevent health problems caused by dehydration.


  1. The facts about high blood pressure [Internet]. www.heart.org. [cited 2022 Oct 13]. Available from: https://www.heart.org/en/health-topics/high-blood-pressure/the-facts-about-high-blood-pressure
  2. Hypertension [Internet]. [cited 2022 Oct 13]. Available from: https://www.who.int/news-room/fact-sheets/detail/hypertension
  3. Aleksandar. Can drinking water lower blood pressure? [Internet]. Aktiia. 2022 [cited 2022 Oct 13].Available from: https://aktiia.com/uk/can-drinking-water-lower-blood-pressure
  4. Water’s unexpected role in blood pressure control [Internet]. ScienceDaily. [cited 2022 Oct 13]. Available from: https://www.sciencedaily.com/releases/2010/07/100706150639.htm
  5. Luger M, Lafontan M, Bes-Rastrollo M, Winzer E, Yumuk V, Farpour-Lambert N. Sugar-sweetened beverages and weight gain in children and adults: a systematic review from 2013 to 2015 and a comparison with previous studies. OFA. 2017;10(6):674-693.
  6. Dehydration and blood pressure: how you could be affected [Internet]. DripDrop. [cited 2022 Oct 13]. Available from: https://www.dripdrop.com/blog/health-wellness/dehydration-and-blood-pressure
  7. Water ENS. Can dehydration cause high blood pressure? [Internet]. [cited 2022 Oct 13]. Available from: https://www.eldoradosprings.com/blog/can-dehydration-cause-high-blood-pressure 

Habeebullah Oladipo

Bachelor of Science - B.Sc. Microbiology, University of Ilorin, Ilorin, Nigeria

Habeebullah is a Microbiologist and an early career researcher with keen interest in Infectious diseases,
Antimicrobial Resistance and global health.
He is currently undertaking his "Bachelor of Pharmacy" in University of Ilorin, Ilorin, Nigeria.

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