How Low Blood Pressure Affects Your Health

With Luke Laffin MD

It’s well established that high blood pressure increases the risk for various conditions, including heart disease and stroke. But what about low blood pressure? Is it always healthy? Here’s what you need to know.

Low blood pressureBlood pressure can also be too low.

What is low blood pressure?

Blood pressure is recorded as a top number (systolic) and a bottom number (diastolic). The top number is the systolic pressure when the ventricles (the two main chambers) of your heart push the blood out against the walls of the arteries as the blood courses through your body, and the lower number is the diastolic pressure, which is the pressure between your heart beats (the rest period), when the blood travels through your heart’s coronary blood vessels. Normal blood pressure is less than 120 mmHg over less than 80 mmHg. Low blood pressure, which is given the medical term “hypotension,” is technically a top number of less than 90 mmHg or a bottom number of less than 60 mmHg.

Can you be healthy and have low blood pressure?

According to Luke Laffin MD, a preventive cardiologist at the Cleveland Clinic, “There are many normal reasons for lower blood pressure, including younger age and small stature.” Some people just have a genetic predisposition to low blood pressure.

Generally, if there are no symptoms, low blood pressure is not considered a problem. Though some people do naturally have blood pressure that tends to be on the low side and have no symptoms.

When is low blood pressure considered a problem?

There is no exact number. Blood pressure is thought to be too low when it starts causing problems. A systolic pressure that drops by 20 mmHg or a diastolic pressure that drops by 10 mmHg can result in symptoms.

What are some symptoms associated with low blood pressure?

Symptoms can include lightheadedness or dizziness, passing out or feeling like you’re going to pass out, fatigue, nausea, clammy skin, or having blurred vision. But how it feels when blood pressure is low can vary greatly from person to person.

How does your body regulate blood pressure?

Your body has complex feedback mechanisms to regulate blood pressure, including dedicated nerves and hormones (such as adrenalin) that are part of the sympathetic nervous system, which is involved in the fight-or-flight reflex. (This reflex involves many physiological changes, including an increase in heart rate, and blood pressure, and is given this name because it’s the body’s response to a threat.) Special nerve receptors in major blood vessels signal a drop in blood pressure and alert your sympathetic nervous system to boost its activity, increasing heart rate and constricting (narrowing) blood vessels. If anything impairs these mechanisms, your blood pressure can drop.

Are certain people more likely to have low blood pressure?

Some people, especially if you have diabetes, are at a higher risk of your blood pressure temporarily dropping after eating or when getting up from a chair or from lying down in bed, for example. The former is what’s called postprandial hypotension and the latter is orthostatic hypotension. Normally, when you're digesting food, or when you change your body position from sitting to standing, your cardiovascular system adapts by beating harder as well as more rapidly, and constricting the diameter of certain blood vessels, such as those far from your intestine where digestion occurs. These physiological changes all collaborate to maintain your blood pressure. But, if these changes do not occur fast or adequately enough, your blood pressure can drop, sometimes to dangerous levels.

What puts people with diabetes at a higher risk of bouts of low blood pressure?

Diabetes and age-related changes (especially in people with cardiovascular disease) can result in damage to your nerves involved in monitoring blood pressure as well as your reflexes that help constrict blood vessels and increase heart rate to compensate for standing up or eating a meal. Your nerve sensors in your arteries that monitor blood pressure may not work as effectively if you have diabetes — especially if you have poor blood sugar control — making them more prone to a drastic drop in blood pressure.

Can a person with high blood pressure also end up with bouts of low blood pressure?

Dr. Laffin explains that treatment of hypertension can sometimes result in episodes of low blood pressure. In other words, the medication prescribed may lower blood pressure too much. “Additionally, certain blood pressure medications have an increased effect if you're dehydrated,” says Dr. Laffin. “For example, ARBs (angiotensin II receptor blockers, such as losartan) and ACE-inhibitors (such as lisinopril) will have more of a blood pressure lowering effect if you're dehydrated.”

What other medications can accidentally cause low blood pressure?

There are a variety of other medications that can unintentionally cause your blood pressure to drop, including cardiovascular drugs, diuretics, and beta blockers that are used to treat high blood pressure. Drugs used to treat erectile dysfunction can also result in low blood pressure, as can certain antidepressants, as well as medications prescribed for Parkinson’s disease.

What are treatments for low blood pressure?

According to Dr. Laffin, “If you're underweight, working to healthfully increase your weight and muscle mass will help to increase your blood pressure.”

Dr. Laffin also recommends the following:

  • Hydrate often to prevent dehydration. When you’re dehydrated, your blood volume drops and, as a result, so does your blood pressure. Drinking adequate fluids increases the volume of your blood. Remember to drink before you’re thirsty, which is often a sign that you're already dehydrated.
  • Eat multiple small meals throughout the day instead of three large ones. This prevents too much blood flowing to your gut to aid in digestion.
  • Get up from a seated or lying position gradually rather than bolting upright.
  • Take blood pressure lowering medications at night. Most BP medications last 24-hours, but the peak effect occurs two to three hours after we take them. If taken at night, this will be while you’re sleeping and help you to avoid your blood pressure getting too low while you're awake.
  • Avoid very hot showers or visiting saunas, hot tubs, or steam rooms. They dilate blood vessels, causing blood pressure to drop. 
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