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How to Understand Blood Pressure Readings

Making sense of blood pressure

Understanding blood pressure isn’t easy, especially when words like “systolic,” “diastolic,” and “millimeters of mercury” (mm Hg) are involved.

By learning some basic concepts, however, you can become an expert in reading and understanding your blood pressure numbers. This is essential for identifying high blood pressure, or hypertension, in its earlier stages to prevent health complications.

What do the numbers mean?

Everyone would like to have healthy, “normal” blood pressure. But what exactly does that mean? When your doctor takes your blood pressure, it’s expressed as a measurement with two numbers, with one number on top and one on the bottom, like a fraction. For example, 120/80.

The top number refers to the amount of pressure in your arteries during contraction of your heart muscle. This is called systolic pressure. The bottom number refers to your blood pressure when your heart muscle is between beats. This is called diastolic pressure. Both numbers are important in determining the state of your heart.

Higher numbers than the ideal range indicate that your heart is working too hard to pump blood to the rest of your body.

What’s a normal reading?

For a normal reading, your blood pressure needs to show a top number that’s between 90 and 120, and a bottom number that’s between 60 and 80.

When both your systolic and diastolic numbers are in these ranges, you’re considered by the American Heart Association (AHA) to be within the normal range for blood pressure.

Note that blood pressure readings are expressed as millimeters of mercury. This unit is abbreviated as mm Hg. A normal reading would be any blood pressure below 120/80 mm Hg and above 90/60 mm Hg. Blood pressure that is too low does not supply your body and heart with enough oxygenated blood. Low blood pressure is known as hypotension.

If you’re in the normal range, no medical intervention is needed. However, you should maintain a healthy lifestyle and a healthy weight to prevent hypertension from developing. Regular exercise and reduced salt intake can also help. You may need to be even more mindful of your lifestyle if hypertension runs in your family.

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Numbers higher than 120/80 mm Hg are a red flag that you need to take on heart-healthy habits.

When your systolic (upper number) is between 120 and 139 mm Hg or your diastolic (lower number) is between 80 and 89, it means you have prehypertension.

Although these numbers aren’t technically considered high blood pressure, you’ve moved out of the normal range. Elevated blood pressure has a good chance of turning into actual high blood pressure, which puts you at increased risk of heart disease and stroke.

No medications are necessary for prehypertension. But this is when you should adopt healthier lifestyle choices. A balanced diet and regular exercise can help lower your blood pressure to a healthy range. This can also help prevent prehypertension from developing into full-fledged hypertension.

Hypertension: Stage 1

You’ll generally be diagnosed with high blood pressure if your systolic blood pressure reaches between 140 and 159 mm Hg, or if your diastolic blood pressure reaches between 90 and 99 mm Hg. This is considered stage 1 hypertension.

However, the AHA notes that if you get only one reading this high, you may not truly have high blood pressure. What determines the diagnosis of hypertension at any stage is if your numbers remain this high over a period of time.

Your doctor can help you measure and track your blood pressure to confirm whether it’s too high. You may need to start taking medications if your blood pressure doesn’t improve after one month of developing a healthy lifestyle.

Hypertension: Stage 2

Stage 2 high blood pressure indicates an even more serious condition. If your blood pressure reading shows a top number of 160 or more, or a bottom number of 100 or more, it’s considered stage 2 hypertension.

At this stage, your doctor will recommend one or more medications for keeping your blood pressure under control. But you should not rely solely on medications to treat hypertension. Lifestyle habits are just as important in stage 2 as they are in the other stages.

Some medications that can complement a healthy lifestyle include:

  • ACE inhibitors to relax blood vessels
  • alpha-blockers used for decreasing arterial resistance
  • beta-blockers to decrease heart rate and relax blood vessels
  • calcium channel blockers to relax blood vessels
  • diuretics to decrease the amount of fluid in your body, including your blood vessels

Danger zone

A blood pressure reading above 180/110 mm Hg indicates a serious health problem. The AHA refers to these high measurements as a “hypertensive crisis.” Blood pressure in this range requires urgent treatment if there are no accompanying symptoms.

You should seek emergency treatment if you have blood pressure in this range along with symptoms such as:

  • chest pain
  • shortness of breath
  • visual changes
  • symptoms of stroke, such as paralysis or loss of muscle control in the face or an extremity
  • blood in the urine
  • dizziness
  • headache

However, sometimes a high reading can occur and then your numbers will return to normal. If your blood pressure measures at this level, your doctor will likely take a second reading after a few minutes have passed. A second high reading indicates that you’ll need treatment either as soon as possible or immediately depending on whether or not you have any of the symptoms described above.

Preventive measures

Normal blood pressure is not cause for complacency. Even if you have healthy numbers, you should take preventive measures to keep your blood pressure in the normal range. This will help you avoid developing hypertension or heart disease.

The following preventive measures can help lower or stave off high blood pressure:

  • Reduce your sodium intake: Ideally, you should not consume more than 2,300 mg per day. Adults who already have hypertension should limit their sodium intake to 1,500 mg.
  • Don’t add salt to your foods: This increases your overall sodium intake.
  • Limit processed foods: While also high in sodium, many of these foods are also low in nutritional value.
  • Reduce your caffeine intake: Talk to your doctor to see if caffeine sensitivity plays a role in your blood pressure readings.
  • Exercise more often: Consistency is key in maintaining a healthy blood pressure reading. It’s better to exercise 30 minutes a day, rather than a few hours on the weekends.
  • Maintain a healthy weight, or lose weight if necessary: Losing even 10 pounds can make an impact on your blood pressure readings.
  • Manage your stress levels: Moderate exercise, yoga, or even 10-minute meditation sessions can help.
  • Reduce your alcohol intake: Depending on your situation, you may need to stop drinking altogether.
  • Quit smoking.

As you age, prevention becomes even more important. Systolic pressure tends to creep up once you’re over 50, according to the AHA. Certain health conditions, such as diabetes, may also play a role. Talk to your doctor about how you can manage your overall health to help prevent the onset of hypertension.


Keeping your blood pressure in the normal range is crucial in preventing complications, such as heart disease and stroke. A combination of healthy lifestyle habits and medications can help lower your blood pressure. Weight loss is also important in keeping your numbers down.

Remember that a single blood pressure reading doesn’t necessarily classify your health in stone. Blood pressure readings taken over time are the most accurate. This is why it’s ideal to have your blood pressure taken by a healthcare professional at least once a year, or more often if your readings are high.

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