Does Dehydration from Heat Cause Increased Heart Rate and Blood Pressure?

Does heat injury and dehydration lead to increased heart rate and elevated diastolic blood pressure?

Hello doctor, my heart rate has been between 100-110 beats per minute, and my blood pressure is around 126-130 systolic and 95 diastolic.
I have undergone blood tests and an electrocardiogram, both of which were normal.
Especially in hot and humid weather, my heart rate increases, and I experience dry mouth and a sensation of heat in my body.
Is my blood pressure and heart rate normal? Could dehydration also lead to these symptoms and cause abnormal blood pressure and heart rate?

An, 30~39 year old female. Ask Date: 2021/06/25

Dr. He Dongjin reply Cardiology

Hello, it is normal for your heart rate to increase in hot weather, and you may experience symptoms such as dry mouth and a sensation of heat in your body.
A heart rate of 100-110 beats per minute and a blood pressure of 126-130 over 95 is indeed within the normal range.
Dehydration can also lead to these symptoms.
Take care from Changhua Hospital.

Reply Date: 2021/06/25

More Info

Dehydration due to heat can indeed lead to increased heart rate and elevated blood pressure. When the body is exposed to high temperatures, it tends to lose fluids through sweating. This loss of fluids can lead to dehydration, which has several physiological effects on the cardiovascular system.

Firstly, dehydration reduces the overall blood volume in the body. When blood volume decreases, the heart has to work harder to maintain adequate blood flow to vital organs. This increased workload can manifest as a higher heart rate, often referred to as tachycardia. In your case, a heart rate of 100-110 beats per minute is considered elevated, especially if it occurs consistently in hot weather.

Secondly, dehydration can lead to a compensatory increase in blood pressure. When blood volume decreases, the body may constrict blood vessels to maintain blood pressure. This can result in elevated systolic and diastolic blood pressure readings. Your blood pressure readings of 126-130 systolic and 95 diastolic are on the higher side of normal, particularly in the context of dehydration and heat exposure.

Additionally, the symptoms you describe—such as dry mouth, a sensation of heat, and increased heart rate—are common indicators of dehydration. When the body is dehydrated, it can also lead to feelings of fatigue, dizziness, and even confusion in more severe cases. It's important to recognize these signs early and take action to rehydrate.

To address your concerns, it is crucial to ensure adequate hydration, especially during hot weather. Drinking water is essential, but in cases of significant fluid loss (like during intense heat or exercise), electrolyte-replenishing drinks can be beneficial. These drinks help restore not just water but also essential electrolytes lost through sweat, such as sodium and potassium.

If you continue to experience elevated heart rates and blood pressure despite adequate hydration, or if you notice other concerning symptoms, it would be wise to consult with a healthcare professional. They can evaluate whether there are underlying conditions contributing to these symptoms, especially considering your previous health evaluations have shown normal results.

In summary, dehydration from heat can lead to increased heart rate and blood pressure due to reduced blood volume and compensatory mechanisms in the body. Staying hydrated is key to preventing these symptoms, and monitoring your condition is essential for maintaining overall cardiovascular health. If symptoms persist, further medical evaluation may be necessary to rule out other potential issues.

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