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Deciphering Blood Pressure

January 4, 2021

We’ve all had our blood pressure taken at least once in our lives, whether at a doctor’s appointment or at the machine near the pharmacy. However, unless actively monitoring their blood pressure, many people have no idea what those two little numbers actually mean for their health.

The Basics of Blood Pressure

Blood pressure measures how hard blood is pushing on the artery walls it travels away from the heart. It’s recorded in millimeters of mercury (mm Hg), as mercury was used in the pressure gauges that first accurately measured blood pressure.

High blood pressure (HBP) can lead to a multitude of life-threatening complications. Knowing your blood pressure helps you and your doctor determine the best way to manage your HBP, whether by lifestyle changes or medication. Even for those who don’t currently suffer from HBP, it’s still important to know your blood pressure so you can monitor any abnormal changes.

Additionally, it’s important to get an accurate reading. Multiple factors can affect your blood pressure measurement, including nervousness, recent nicotine or alcohol consumption, a full bladder, and crossing your arms or legs during the reading.

High vs. Low Blood Pressure

Having high blood pressure means your heart is working too hard to pump your blood. If HBP isn’t caught or managed, it can put you at greater risk of a heart attack, stroke, heart failure, kidney disease, and even vision loss. If possible, be informed of your family’s blood pressure history to determine if you’re at a greater risk of developing HBP.

What’s considered “low blood pressure” varies from person to person, but it’s not typically considered a problem unless it’s causing symptoms—shock, fainting, or fatigue, for example. Some medical conditions cause a decrease in blood pressure, like dehydration, pregnancy, blood loss, problems with the endocrine system, and severe infection, so it’s important to determine the underlying cause if you’re experiencing sudden low blood pressure.

What Do the Blood Pressure Numbers Mean?

Blood pressure is recorded similarly to a fraction, with a larger number on top and a smaller number on the bottom. The top and larger number, the systolic blood pressure, represents the pressure level in the arteries during your heart’s contractions. The bottom, smaller number is the diastolic blood pressure, which measures the pressure on the arteries between contractions. The following ranges are used to determine which readings are normal and which qualify as elevated or high blood pressure.


As the name suggests, this is the healthy range for blood pressure. Continue habits that promote a healthy heart, like regular exercise and a healthy diet.


At this range, you have an increased chance of developing HBP unless you take steps to manage your blood pressure.

High Blood Pressure (Stage 1)

At this stage, your doctor will suggest lifestyle changes that prioritize heart health, though they may also recommend medication if diet and exercise don’t improve your HBP.

High Blood Pressure (Stage 2)

Stage two HBP will likely requires lifestyle changes as well as one or more blood pressure medications to manage.

Hypertensive Crisis

This range of blood pressure requires medical attention. Especially if you’re experiencing chest or back pain or shortness of breath, call 911.

If you have questions about your blood pressure or concerns about family history, your doctor will be able to help you develop a health plan to manage or reduce your risk of HBP. For more articles on health and safety, visit the Specialized Health and Safety blog.