You’ve probably heard a lot about blood pressure as you’ve gotten older. You may have even learned how to check it yourself at home and keep track of how your numbers change over time depending on your habits.

But what do those numbers on your blood pressure monitor really mean? And why should you pay attention to them?

When your doctor tells you “Your blood pressure is a little high,” “Your blood pressure is a little low,” or “Your blood pressure is improving,” what are they really saying about your health?

What is blood pressure?

To get a clear picture of what “blood pressure” actually is, think of your heart as a pump. The pumping action of your heart keeps blood flowing to all parts of your body, delivering the oxygen and nutrients you need to live and thrive.

As your blood flows throughout your body, it pushes against the sides of your blood vessels, especially your arteries, the vessels that carry oxygen-rich blood away from your heart. The amount of force your arteries are under when blood is flowing through them is called blood pressure.

Your healthcare team can get a good general idea of how hard your heart is working by measuring your blood pressure.  In fact, blood pressure is such an important indicator of your health that it’s referred to as one of your “vital signs.” Other vital signs include things like heart rate (pulse), body temperature, and respiration rate.

What the numbers mean

Each blood pressure measurement is recorded as two numbers: A first or “top” number, then a slash, and a second or “bottom” number. These numbers represent the two parts of your heartbeat:

  1. The squeeze, when your heart pumps blood through your arteries, and
  2. the release–or resting period– before the next squeeze. The first number measures the squeeze, and the second number measures the release.

When a healthy heart is pumping effectively, these two blood pressure numbers will be within a certain range. Numbers that are higher or lower than the ideal healthy range indicate your heart is working too hard, or not hard enough.

You can talk with your doctor about your individual ideal, or target, range for your own blood pressure numbers.

If your blood pressure numbers are significantly higher or lower than ideal, your health can be at risk. Your doctor can talk to you about ways to maintain your blood pressure within your ideal target range.

What is high blood pressure?

High blood pressure, also referred to as hypertension, means your blood is exerting a larger-than-ideal amount of force on the walls of your blood vessels. This extra stress and strain makes your blood vessels thicker, less flexible, and weaker over time.

How high blood pressure affects heart health

A weakened artery that remains under increasing pressure will bulge (aneurysm), and may eventually rupture, causes fatal internal bleeding (hemorrhage).

Constant high pressure damages the inside walls of your blood vessels. The damaged areas cause fatty deposits (called plaque) to build up, like gunk in a drainpipe. The buildup makes it difficult for blood to move through, forcing your heart to pump even harder to get your blood where it needs to go.

And that’s not all…

If enough plaque builds up inside your vessels, it can clog them completely, preventing blood from flowing at all. Another danger is that pieces of plaque can break off and block other, smaller, vessels.

  • A blocked blood supply to the heart can lead to a heart attack.
  • A blocked blood supply to the brain can lead to a stroke.

Other ways high blood pressure affects your health

High blood pressure not only puts you at increased risk for heart attack and stroke, it affects your health in other ways as well. Additional health consequences of high blood pressure include:

  • Kidney damage: Uncontrolled long-term high blood pressure damages the vessels flowing into and out of your kidneys making it difficult for them to filter waste from your body properly. This can cause your blood pressure go up, creating a vicious cycle that ends in kidney failure.
  • Vision problems: When uncontrolled long-term high blood pressure damages the fragile blood vessels in your eyes, you’ll experience blurred or distorted vision and even vision loss.
  • Other health concerns: Uncontrolled high blood pressure can also bring on chest pain (angina), soreness and cramping in your legs and arms (peripheral artery disease), and even sexual problems (low libido in women and erectile dysfunction in men).

Even if you don’t feel any symptoms at first, or at all, the constant strain high blood pressure puts on your body has very serious health consequences over time. That’s why it’s so important to keep your blood pressure well controlled.

What is low blood pressure?

Blood pressure that’s too low can have negative health consequences, too. Low blood pressure can be caused by numerous different factors, including drug effects, dehydration, heart failure, heart arrhythmias, changes in body temperature, allergic reactions, and more.

How low blood pressure affects health

The most serious health consequences of low blood pressure occur when blood pressure drops suddenly. The sudden drop in pressure can make you unsteady on your feet, and cause you to fall. This kind of thing can happen when you stand up suddenly or stand up for long periods of time.

Low blood pressure can cause blurred vision, dizziness or lightheadedness, fatigue, nausea, and a lack of concentration among other symptoms, all of which put you at increased risk for falling. It can be difficult to recover from injuries sustained from falls, and one way to prevent falling is to prevent low blood pressure.

Why do my blood pressure numbers change?

Blood pressure numbers change often and naturally—every day, throughout the day. Typically, your blood pressure is lower at night while you’re sleeping and rises during the day when you’re active.

But your blood pressure may also change for a variety of other reasons. Your blood pressure will change thanks to other medical conditions you may have, like sleep apnea, anxiety, neurological disorders, thyroid disorders, kidney disease, or diabetes just to name a few. The medications you’re taking (or not taking) can also change your blood pressure readings. And environmental circumstances including life stress, tobacco exposure, night-shift work, and the amount of sodium in your food, may all contribute to variations in your numbers.

Tracking your blood pressure in between office visits and monitoring the trends of how it changes over time is one of the best ways to improve your personal strategy for controlling your blood pressure.

Bottom line

Your blood pressure is a basic indicator of over-all health. When your blood pressure is too high or too low, your health is at risk. Controlling your blood pressure effectively helps you reduce your risk of life-threatening health conditions.

Controlling your blood pressure means keeping the numbers used to measure it within an ideal range that’s not too high, and not too low. Your doctor establishes the range that is ideal for you, based on your age, medical conditions, medications, and other factors.

It’s important to take your blood pressure seriously. Follow your doctor’s advice for taking medications and making lifestyle changes. Send your blood pressure data in regularly. And work on building healthier habits that will lower your risk of serious health consequences and improve your overall health and quality of life.

Lane Therrell

Author Lane Therrell

Lane Therrell leads the Clinical Team at She's a board-certified Family Nurse Practitioner, nurse educator, freelance writer, and health coach in private practice. When she's not leading the Clinical Team or otherwise helping her patients, clients, or students, she's enjoying the great outdoors – preferably in remote wilderness areas.

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