CPR First Aid

What Happens to Your Blood Pressure When You are Dehydrated

What Happens to Your Blood Pressure When You are Dehydrated?

Did you know that when you suffer from dehydration, your blood pressure can be affected? The majority of people are aware of how important sufficient hydration is for health. After working out or in hot weather, people drink water. However, your body requires a lot of fluids in certain circumstances to avoid dehydration. One must be aware of these situations and must be familiarized with the possible effects of dehydration on blood pressure. In this blog, you will learn how to manage blood pressure when dehydration happens. 

What is Blood Pressure?

According to Mayo Clinic, blood pressure is a measure of how hard your blood pushes against your arteries as it moves throughout your body. Depending on the type of activity you are engaging in, your blood pressure can fluctuate between high and low.

What is Hypertension?

High blood pressure, also called hypertension, is blood pressure that is higher than normal. This occurs when the force of your blood against the walls of your blood vessels, is consistently too high. High blood pressure is harmful because it makes the heart work harder and less efficiently. The guidelines used to measure high blood pressure varies among healthcare professionals

What is Hypotension?

Low blood pressure is also known as hypotension. Most doctors would say that you have low blood pressure if it is below 90/60 mmHg. Your doctor will refer to this as ‘90 over 60’.

What Do Blood Pressure Numbers Mean?

According to CDC, blood pressure is measured using two numbers:

  • The first number, called systolic blood pressure, measures the pressure in your arteries when your heart beats.
  • The second number, called diastolic blood pressure, measures the pressure in your arteries when your heart rests between beats.

What are the Causes of Hypertension and Hypotension?

There are different causes why a person acquires hypertension and hypotension. Hypertension has varied causes depending if it is primary or secondary hypertension. This is the same case with hypotension, it depends on your body position or your underlying medical health concern.

The Connection Between Blood Pressure and Dehydration

There is a significant effect on blood pressure when we are dehydrated. Dehydration can cause your blood volume to decrease. If you’re dehydrated, your blood volume and blood pressure can drop too low. This can prevent your tissues and organs from getting the amount of oxygen and nutrients they need to stay healthy. 

In extreme circumstances, your blood pressure could fall so low that your body experiences shock. When your organs aren’t getting enough oxygen, you could go into shock, a condition that is potentially fatal. One of the main causes of shock is low blood volume from dehydration. The brain, kidneys, liver, and other organs stop functioning correctly in the absence of oxygen. Low blood pressure can permanently harm organs, tissues, and cells if left untreated.

When your body is dehydrated, it releases higher amounts of a chemical called vasopressin. Vasopressin helps your kidneys retain water, which can prevent you from losing more water through urination. At the same time, it causes your blood vessels to constrict, which then causes your blood pressure to increase. When this situation persists, you can develop high blood pressure. 

Causes of Dehydration

There are many reasons why your body becomes dehydrated. It can occur when you are sick and have diarrhoea or are vomiting. Your body loses electrolytes before it’s able to absorb essential fluids in the intestines. Physical activity in hot areas can also make you lose fluid and electrolytes. 

Dangers of Dehydration

According to Mayo Clinic, anyone can become dehydrated, but certain people are at greater risk:

  • Infants and children. The most likely group to experience severe diarrhoea and vomiting, infants and children are especially vulnerable to dehydration. Having a higher surface area to volume area, they also lose a higher proportion of their fluids from a high fever or burns. Young children often can’t tell you that they’re thirsty, nor can they get a drink for themselves.
  • Older adults. As you age, your body’s fluid reserve becomes smaller, your ability to conserve water is reduced and your thirst sense becomes less acute. These problems are compounded by chronic illnesses such as diabetes and dementia, and by the use of certain medications. Older adults also may have mobility problems that limit their ability to obtain water for themselves.
  • People with chronic illnesses. Having uncontrolled or untreated diabetes puts you at high risk of dehydration. Kidney disease also increases your risk, as do medications that increase urination. Even having a cold or sore throat makes you more susceptible to dehydration because you’re less likely to feel like eating or drinking when you’re sick.
  • People who work or exercise outside. When it’s hot and humid, your risk of dehydration and heat illness increases. That’s because when the air is humid, sweat can’t evaporate and cool you as quickly as it normally does, and this can lead to an increased body temperature and the need for more fluids.


Dehydration can lead to serious complications, including:

  • Heat injury. If you don’t drink enough fluids when you’re exercising vigorously and perspiring heavily, you may end up with a heat injury, ranging in severity from mild heat cramps to heat exhaustion or potentially life-threatening heatstroke.
  • Urinary and kidney problems. Prolonged or repeated bouts of dehydration can cause urinary tract infections, kidney stones and even kidney failure.
  • Seizures. Electrolytes — such as potassium and sodium — help carry electrical signals from cell to cell. If your electrolytes are out of balance, the normal electrical messages can become mixed up, which can lead to involuntary muscle contractions and sometimes to a loss of consciousness.
  • Low blood volume shock (hypovolemic shock). This is one of the most serious, and sometimes life-threatening, complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body.

First Aid for Dehydration

Individuals who have mild to moderate dehydration due to diarrhoea, vomiting, or fever can be better by consuming more water, fluids, vegetables and fruits.

First aid for cases of extreme dehydration should focus on stabilizing the patient and securing prompt medical attention.

Call 000 right away if you notice any severe dehydration-related symptoms. They will give medical advice and assistance in getting the patient to the hospital so they can get the treatment they need. The majority of severe dehydration treatment strategies include intravenous (IV) therapy to replenish lost fluids and electrolytes.

First Aid Courses for Dehydration in Liverpool

Risks of dehydration, hypertension and hypotension can be prevented. Early detection of signs and symptoms will help you manage it. If you are interested in enrolling in a first aid course in Liverpool, contact CPR First Aid for more information.CPR First aid courses and training are open to all since emergency situations such as complications caused by dehydration can happen to all ages, anywhere in Australia. HLTAID010 Provide an emergency first aid response is one of our popular courses. Contact us anytime for your queries.


Dehydration can greatly affect blood pressure. One of the best ways to avoid hypertension, low blood pressure and damage to organs is to avoid dehydration. This can be managed at home for mild to moderate cases. However, someone who is severely dehydrated must seek medical attention immediately and dial 000. Being aware of the early warning signs and symptoms can save your life. Dehydration should be adequately managed early on to avoid problems and even death. Learn more by joining us by enrolling in a  first aid course in Liverpool, contact CPR First Aid for more information.

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