What Is Your Blood Pressure Telling You?

Blood pressure readings provide clues for circulatory health

Medically reviewed by Jane Kim, MD

Blood pressure (BP) measures your heart's force to pump blood through its four chambers and out to the rest of your body. An ideal reading is about 120/80 millimeters of mercury (mmHg). The need for blood pressure medications depends on how high your blood pressure gets and the lifestyle changes you can make to help control it.

This article will explore normal, low, and high blood pressure ranges and what to do if your blood pressure gets too low or too high.

Medical Definition: What Is Blood Pressure?

Blood pressure is a combination of two measurements: systolic and diastolic blood pressure.

Systolic

The top or first number in your blood pressure measurement is the systolic pressure. This number represents how much force your heart muscle exerts when it contracts during each beat. During this systole phase, blood is pumped:

• Through the chambers of your heart

• To your lungs to pick up fresh oxygen

• Back to your heart

• Out of the heart to the rest of your body through your blood vessels

This number represents the strength of your heart's contraction and the force your blood puts on your artery walls with each pump.

Diastolic

The bottom or second number in your blood pressure reading measures diastolic pressure. This number is the pressure exerted against the artery walls during the time when the heart muscle relaxes between contractions.

What Are Blood Pressure Readings?

Blood pressure can be measured a few ways, but the most common is with a blood pressure cuff worn on the arm—a sphygmomanometer. The force of your blood is measured in millimeters of mercury, abbreviated as mmHg. Below are some low, normal, and high ranges for these readings and their meaning.

Low BP

Some people have normal blood pressure readings lower than 120/80. For others, low blood pressure can be a sign that your heart is weak or the blood volume in your body is too low. Your blood pressure isn't considered "low" until the reading is below 90/60 mmHg, but tolerable low blood pressure can depend on your situation.

A healthcare provider may not diagnose you with low blood pressure (hypotension) unless you start to experience symptoms such as:

• Blurry vision

• Confusion

• Dizziness

• Fainting

• Heart palpitations

• Nausea
  

Healthy BP

Normal blood pressure is considered 120/80 mmHg for most adults. A normal blood pressure range is usually a bit higher in older adults to compensate for the stiffening of blood vessels that often occurs normally with age.

High BP

There are different ranges of blood pressure readings that are considered high. Your healthcare provider will take into account your individual health and lifestyle. If you are stressed or anxious, or if you take certain medications, your blood pressure can jump up, but not for long.

Usually, a healthcare provider won't officially diagnose you with high blood pressure (hypertension) unless your blood pressure is elevated on more than a few readings at different appointments. Even then, your diagnosis will depend on the range your blood pressure measurement falls into.

• Normal: Less than 120/80

• Elevated: Between 120 and 129 systolic and less than 80 diastolic

• Stage 1 hypertension: Between 130 and 139 systolic or between 80 and 89 diastolic

• Stage 2 hypertension: 140/90 and higher

Your Blood Pressure and Salt

Dietary changes may be a part of your treatment plan for high blood pressure. Salt is a big concern regarding heart-healthy diets and managing blood pressure. Research shows that consuming a lot of salt can increase your blood pressure and contribute to fluid retention and other issues that conflict with a healthy heart.

Related: What Is the DASH Diet?

What Does Blood Pressure Indicate?

A blood pressure reading in the normal range is usually a sign of healthy cardiovascular function.

Low blood pressure—especially when it comes with symptoms—can be a sign of some of the following problems:

• Adrenal gland disorders

• Anaphylaxis from severe allergic reactions

• Certain medications

• Dehydration
  

• Fatigue
  

• Neurally mediated syncope

• Orthostatic hypotension

• Prolonged bed rest

• Septic shock and severe illness

• Significant bleeding
  

• Thyroid dysfunction
  

Hypertension is often related to the following:

• Age

• Family history

• Gender

• Heart disease

• High cholesterol

• Obesity

• Poor diet

• Race
  

• Stress
  

Monitoring Blood Pressure

Regular blood pressure measurements should be a part of your routine wellness care. Since high blood pressure typically develops gradually without any symptoms, you may only notice hypertension by chance at a preventive visit or at-home blood pressure checks. Your blood pressure is measured with a manual or automated cuff placed around your arm. To get the most accurate measurement, the following things can help:

• Try to relax

• Empty your bladder first

• Sit in a comfortable chair with back support

• Place both of your feet flat on the floor (don't cross your legs)

• Make sure your blood pressure cuff is against your skin, not over your clothes

• Rest your arm at chest height

In some cases, like when you are severely ill or having surgery, and you need the most accurate and sensitive blood pressure reading possible, your healthcare team may have to use a direct, usually invasive method for blood pressure management.

This is done by inserting a catheter into an artery in your wrist or groin. The catheter takes direct, real-time measurements to identify and treat any dangerous blood pressure changes.

Blood Pressure Treatments

Healthcare providers often take a multipronged approach to treating blood pressure. They'll likely recommend diet and lifestyle changes and, depending on your overall health, may prescribe one or more medications within the following categories:

• Angiotensin converting enzyme (ACE) inhibitors

• Angiotensin II receptor blockers (ARBs)

• Beta-blockers

• Calcium channel blockers
  

• Diuretics

• Vasodilators

Related: How Long Does It Take for Blood Pressure Medication to Work?

Summary

Blood pressure is a measurement of the force of blood pumped out of your heart against the walls of your blood vessels. Your blood pressure measurement can give your healthcare provider crucial information about nearly every body system.

Typically, high blood pressure develops without symptoms and is diagnosed by chance after several high readings at preventive care appointments. Low blood pressure, on the other hand, is diagnosed following spells of fainting or dizziness. Talk to a healthcare provider about your personal and family medical histories, any symptoms you've been having, and how often you need your blood pressure checked.