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Besides feeling thirsty, could dehydration have bigger effects on your health?

Signs of nutrient deficiencies usually take weeks or months to appear, but this isn’t the case for water. Dehydration symptoms like a dry mouth, increased thirst, headache and decreased urination can come on within a few hours if you’re not keeping tabs on your daily water and fluid intake. But mild dehydration is easily remedied with water or a water-electrolyte beverage.

Consequently, most people consider dehydration a temporary health issue with little to no long-term effects. Still, research has suggested that frequently being dehydrated may increase one’s risk of developing high blood pressure. And this could be a problem, considering that the average American adult drinks only around 44 ounces of water daily—not meeting the daily recommendations, per the Centers for Disease Control and Prevention.

What’s the Connection Between Dehydration and Blood Pressure?

When homeostasis, a state of equilibrium, is even slightly disturbed, the body has thousands of backup scenarios to initiate immediately to stabilize things and keep them running smoothly. The body’s response to early dehydration is a great example! Here’s how it works when you don’t drink enough water or haven’t had enough fluids.

  • In the early stages of dehydration, blood volume (the amount of blood circulating in the body) decreases. This is because water makes up over half of your blood volume, per the National Institutes of Health.
  • Decreased blood volume also causes an increased concentration of sodium in your blood. For reference, according to MedlinePlus, a normal range of blood sodium levels is considered 135 to 145 mEq/L. So, a value at the upper end of this range or above would be considered mild dehydration.
  • The body does two things when it senses changes in blood volume and sodium level. The first is to initiate thirst in hopes you’ll be prompted to find some hydration, and the second is to trigger the secretion of anti-diuretic hormone.
  • The increase in ADH (also known as vasopressin) tells the kidneys to temporarily retain water to prevent any fluid loss (such as urination) and keep sodium concentration from increasing further. It also constricts blood vessels, which causes a temporary increase in blood pressure.
  • Since blood volume is low, this increase in pressure is essential to help blood circulate.
  • Once the rehydration process starts, ADH levels slowly decline and pressure returns to where it was previously.

How Frequent Dehydration Can Lead to High Blood Pressure

How could dehydration really lead to hypertension (or ongoing high blood pressure) if the changes above are temporary and resolved with hydration? This question is why researchers took a deeper look at the long-term effects that frequent episodes of dehydration may have. And it’s a good thing they did, because regular episodes of mild dehydration have been associated with an increased risk for obesity, type 2 diabetes, dementia, chronic kidney disease and inflammatory bowel disease. Plus, some research suggests that frequent dehydration impacts the cardiovascular system, including contributing to hypertension..


According to the American Heart Association, there are two categories of hypertension; stage 1 and 2. Stage 1 is when your blood pressure regularly ranges between 130-139/80-89 mm Hg, whereas stage 2 is when your blood pressure is 140/90 mm Hg or higher.

A 2019 study published in Nutrients suggested that frequent dehydration due to inadequate water intake leads to changes in blood vessel function and blood pressure regulation. Over time, this can lead to long-term changes. In fact, researchers suggested that dehydration could be considered a primary risk factor for hypertension, blood clots, stroke and coronary heart disease because of these changes. Another study, published in 2022 in the European Heart Journal, found that high levels of sodium in the blood due to frequent dehydration may increase the risk of heart failure by 39%. And according to the AHA, high blood pressure is one of the most common causes of heart failure.


Related: Staying Hydrated May Help You Live a Longer and Healthier Life, a New Study Suggests

The Bottom Line

It’s probably smart to consider an ongoing lack of adequate hydration as a risk factor for hypertension. This risk seems to stem from high levels of ADH and subsequent changes to blood pressure and the health of blood vessels that occur over time. While the body’s backup plan when it senses dehydration is lifesaving, the response isn’t intended to appear regularly.


It’s important to note that factors like age, weight, and height should be considered to determine how much water you should drink. And, drinking water isn’t the only way to hydrate; certain foods can help you meet your needs too.

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