It’s always important to stay hydrated. After all, more than half of the human body is made of water.

Drinking water keeps you from becoming thirsty and can help cool you off on a hot day. But staying hydrated provides many other health benefits, such as regulating bowel movements and keeping your joints lubricated.

If you are not drinking enough water, you may become dehydrated. Dehydration can lead to a series of symptoms, so it is key to recognize each to receive proper care. Here’s what to know about dehydration, including how it affects blood pressure.

What causes dehydration?

Dehydration occurs when the body is lacking the adequate amount of fluids (primarily water) that it needs to function. If you are losing or using more fluids than you are taking in, you will become dehydrated.

The human body loses fluids in several ways, such as sweating, breathing, urination and defecation, as well as through tears and saliva. When you are not actively and sufficiently replacing those lost fluids, dehydration occurs.

While not drinking enough liquids is one cause for dehydration, it can be triggered by other health conditions, such as diarrhea, vomiting or excessive sweating.

Anyone can become dehydrated. Those at higher risk, however, are infants, children and older people. Infants cannot and children often do not communicate when they are thirsty, making them more prone to dehydration. The same goes for older people, especially those who have cognitive issues.

Dehydration can also be worsened by pre-existing conditions that lead to loss of fluids, such as diabetes causing frequent urination.

Can dehydration cause high blood pressure?

Dehydration can play a role in causing high blood pressure.

When you’re dehydrated, your sodium levels tend to rise. As you are losing fluids, the amount of water and salt in the body becomes unbalanced. For your body to function properly and maintain homeostasis, it needs to be at a certain level of the two substances.

In order to get back to that level, the hormone vasopressin is released to try to retain water, according to the Cleveland Clinic. Vasopressin can cause your blood vessels to tighten, which leads to a rise in blood pressure.

Can dehydration cause low blood pressure?

Dehydration can also cause low blood pressure.

Water makes up to 60% of the human body. The blood in your body is about 90% water, according to the Cleveland Clinic. On average, an adult has about 1.2 to 1.5 gallons – or 10 units – of blood in their body, states the American Red Cross.

When you are dehydrated, you are losing fluids in your body, including in your blood volume. Blood volume refers to the total amount of fluid circulating in your heart. Your heart is responsible for sending blood to other parts of the body.

If you are dehydrated, you may experience low blood volume. When you have low blood volume, your blood is not flowing properly and may not be reaching your organs the way it should. This can lead to low blood pressure.

Dehydration symptoms

Dehydration symptoms vary depending on someone’s age, according to the Cleveland Clinic and Mayo Clinic.

In adults, dehydration symptoms can include:

  • Extreme thirst
  • Less frequent urination
  • Dark-colored urine
  • Fatigue
  • Chills
  • Constipation
  • Dizziness
  • Red (flushed) skin
  • Loss of appetite
  • Muscle cramps
  • Confusion, headache

In infants or children, dehydration symptoms can include:

  • Dry tongue, mouth and lips
  • No tears when crying
  • Sunken eyes, cheeks
  • Sunken soft spot on top of infant’s head
  • Irritability
  • Less frequent urination
  • Dry skin

If you or someone experiences any of the symptoms for a prolonged period, seek medical attention.

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