Dehydration and Low Blood Pressure

by Lisa Nelson, RD, LN Health Professional

I realize your bigger concern tends to be how to LOWER high blood pressure, but today I want to touch on the reverse so you are aware of this potential problem.

Low blood pressure, also known as hypotension, is when your blood pressure drops below 90 mm Hg systolic (top number) or 60 mm Hg diastolic (bottom number).

If your blood pressure is normally on the low side, it's not a concern as long as you are not experiencing symptoms associated with low blood pressure.

Symptoms include:



Lack of concentration



Blurred vision

Rapid, shallow breathing


If you are experiencing these symptoms, you need to take action to correct and prevent blood pressure from dropping too low.


Dehydration and blood pressure

Dehydration can actually cause your blood pressure to be low"and not in a good way.

Dehydration is a lack of fluid in the body, often caused by inadequate fluid intake or excess fluid loss. Running a fever and perspiring are two conditions that can lead to fluid loss. Some medications, such as diuretics and laxatives, can also result in fluid losses.

If you are dehydrated, the body struggles to deliver oxygen and nutrients, as well as remove waste products. The body cannot store fluid, so if must be replenished daily.

Feeling thirsty

Your body is comprised of 60% water. Being just 5-6% dehydrated can lead to feelings of fatigue and increased heart rate. Thirst is not a reliable indicator for dehydration. If you are thirsty, a certain percent of your body is already dehydrated.

You can monitor your hydration by paying attention to the color of your urine. Pale and clear urines indicates good hydration, while dark urine means you are dehydrated and need to drink more fluids.

Daily fluid intake

A general rule of thumb is to drink eight, 8-ounce glasses of water daily. However, the exact amount you need each day depends on your individual body size, lifestyle, and medical history. As long as you are not drinking excessively large quantities of water, it is better to drink too much versus too little.

Prevent dehydration

While water is your best choice for rehydrating, there are many options to obtain daily fluids.

  • Fruits and vegetables

  • Soups

  • Gelatin

  • Pudding

  • Milk

  • Juice

As with any change, even making a move to boost water intake can be a struggle.

Lisa Nelson, RD, LN
Meet Our Writer
Lisa Nelson, RD, LN

Lisa Nelson RD, a registered dietitian since 1999, provides step-by-step guidance to lower cholesterol and lower blood pressure, so you can live life and enjoy your family for years to come. Lisa's passion for health comes from her own family history of heart disease, so she doesn't dispense trendy treatments; Lisa practices what she teaches in her own daily life. Because her own health is the foundation of her expertise, you can trust that Lisa will make it truly possible for you to see dramatic changes in your health, without unrealistic fads or impossibly difficult techniques.