What do the different blood pressure numbers mean

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What do the different blood pressure numbers mean

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Q. When I am monitoring my blood pressure, which number is most important — top, bottom, or both?

A. While both numbers in a blood pressure reading are essential for diagnosing and treating high blood pressure, doctors primarily focus on the top number, also known as systolic pressure.

Systolic pressure reflects the force produced by the heart when it pumps blood out to the body, while diastolic blood pressure (the bottom number) is the pressure in your blood vessels when the heart is at rest.

Over the years, research has found that both numbers are equally important in monitoring heart health. However, most studies show a greater risk of stroke and heart disease related to higher systolic pressures compared with elevated diastolic pressures. That's especially true in people ages 50 and older, which is why doctors tend to monitor the top number more closely. The reason for the difference in risk may be related to the force put on the arteries when blood rushes out of the heart.

The American Heart Association now defines high blood pressure as 130/80 mm Hg or higher. The new guidelines recommend you check your blood pressure often, ideally with a home monitor, to help your doctor determine if you need to make lifestyle changes, begin medication, or alter your current therapy.

— by Howard LeWine, M.D.
Editor in Chief, Harvard Men's Health Watch

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No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

We all know that blood pressure is an important part of our overall health. But not everyone knows what’s meant by “high” blood pressure, or what it looks like as a measurement.

High blood pressure, or hypertension, is when your blood is pushing too strongly through your body. High blood pressure increases your risk for a range of medical conditions, which is why managing your blood pressure and knowing what blood pressure measurements mean is part of the equation for better health. The good news is that it can be possible to lower blood pressure without medication.

Keep reading to learn what’s considered high blood pressure, what your blood pressure should ideally be and what you can do to reach your target numbers.

What does blood pressure tell you?

The heart is good at performing under pressure. It consistently pumps blood throughout your blood vessels, providing every part of your body the oxygen you need to live. Blood pressure measures the force of your blood pushing against the walls of your blood vessels.

If your blood pressure is high, it means your heart is working too hard and the force of the blood flowing through your vessels is too high. This increased pressure can cause your arteries to thicken or harden, and for your blood vessels to weaken, which can lead to serious health conditions.

How to read blood pressure numbers

Blood pressure readings have two numbers, which are read as one number “over” the other. Each number is a different measurement, but they work together to give you and your doctor a look at your health.

What does the top number of blood pressure mean?

The top number of your reading is called systolic blood pressure. It tells you the force of the blood against artery walls when your heart beats.

What does the bottom number of blood pressure mean?

The bottom number is called diastolic blood pressure. It tells you what your blood pressure is when your heart is at rest between heartbeats.

What should your blood pressure be? Blood pressure readings explained

Blood pressure categorySystolic mm Hg
(top number)
and/orDiastolic mm Hg
(lower number)
NormalLess than 120 and Less than 80
Elevated120 – 129 and Less than 80
High blood pressure
stage 1
130 – 139 or 80 – 89
High blood pressure
stage 2
140 or higher or 90 or higher
Hypertensive crisis Higher than 180 and/or Higher than 120

What’s considered a normal blood pressure range?

Blood pressure readings are classified into different categories, each with their own meaning and potential health concerns.

Normal blood pressure

A normal blood pressure is at or under 120 systolic over 80 diastolic. If your blood pressure reading is at or under 120 over 80, you have healthy blood pressure and you can keep doing what you’re doing.

Elevated blood pressure

If a reading is between 120-129 systolic and less than 80 diastolic, it’s considered elevated. If you consistently have readings within this range, it means you’re likely to develop high blood pressure unless you make changes to keep your blood pressure under control.

High blood pressure

If your readings are consistently at or above 130 over 80, you have high blood pressure. The medical term for high blood pressure is hypertension. Hypertension is divided into two stages of severity:

  • Stage 1 hypertension – 130-139 systolic or 80-89 diastolic.
  • Stage 2 hypertension – 140 or higher systolic or 90 or higher diastolic.

A hypertensive crisis

If you have a blood pressure reading that is above 180 in the top number or above 120 in the bottom number, you may be having a hypertensive crisis, which is a medical emergency. Blood pressure this high can damage your blood vessels and could lead to a stroke.

Here’s what to do: Wait five minutes and retest your blood pressure to confirm that the reading is accurate. If your numbers are just as high, call 911 immediately.

What causes high blood pressure?

High blood pressure is something that can affect your heart at any age. And genetics (such as a family history of heart disease), age and ethnicity can all play a role. But in as many as 95% of reported cases, doctors can’t find a direct underlying cause.

Other risk factors that can contribute to high blood pressure include:

  • Smoking
  • Being overweight or obese
  • Not exercising enough
  • A diet that includes too many fatty foods and too much salt
  • Drinking more than 1 to 2 alcoholic beverages per day
  • Kidney disease
  • Adrenal and thyroid disorders
  • Sleep apnea

What does high blood pressure feel like?

High blood pressure often doesn't have any symptoms, so you usually don't feel it. That’s why it’s important to stay up to date on your preventive care – screenings can help identify potential problems like elevated blood pressure when it’s easiest to treat.

If your blood pressure reaches extremely high levels, you may get a headache, shortness of breath or a nosebleed. However, these symptoms may not be specific to your blood pressure. Critically high blood pressure can be caused by conditions that can have similar symptoms, like strokes, heart attacks, heart failure, kidney failure or certain drug interactions.

How to manage your blood pressure

The best way to treat high blood pressure is often through a combination of lifestyle changes. These can include:

Changes to your diet

There are plenty of ways to lower your blood pressure through diet. You can start by making small changes like avoiding high-sodium foods or choosing healthier snacks. The ultimate goal is to create a heart healthy diet you can sustain with your own willpower and the support of your family, doctor and friends.

Maintaining a healthy bodyweight

If you’re overweight or obese, the extra strain on your heart can contribute to high blood pressure. But losing even 10 pounds can make a big difference.

Exercising regularly

All forms of physical activity are good for your health. But aerobic activities in particular – like walking, biking and swimming – can strengthen your heart. Aim for a total of 30 minutes most days to get the best benefits of exercise.

Limiting alcoholic drinks

Alcohol increases blood pressure. Women should try to limit themselves to one drink a day. For men, the number should be no more than two.

Getting quality sleep

If you get less than six hours of sleep each night, you may have an increased chance of getting high blood pressure. So, make good sleep a priority. This may mean practicing good sleep hygiene, such as avoiding screens and liquid before bed. If conditions like insomnia or sleep apnea are getting in the way, consider talking to a sleep medicine doctor.

Stopping smoking

Tobacco products are incredibly bad for your heart. If you smoke or vape, quitting is the best thing you can do for your heart – and the rest of your body.

Reducing stress

High stress levels can increase blood pressure – and if you experience a lot of it over time, stress can also increase your risk of heart disease. So, look for ways to relieve stress, such as deep breathing exercises, meditation and exercise. So, look for ways to relieve stress, such as deep breathing exercises, meditation and exercise.

Medications

If you’re not able to get your blood pressure down with lifestyle changes alone, your doctor may recommend blood pressure medications. Even if you take medication for high blood pressure, you’ll probably still need to make some lifestyle changes to see and maintain long-term results.

Medications for high blood pressure

There are a variety of medications that can help manage high blood pressure. Again, medication is typically recommended when lifestyle changes don’t produce results, and in more serious blood pressure cases like stage 1 or stage 2 hypertension. Medications for high blood pressure include:

  • Alpha, beta and alpha-beta blockers–Stop epinephrine and similar hormones from affecting the cardiovascular system, allowing the muscles of the heart and arteries to stay relaxed.
  • Angiotensin-converting enzyme (ACE) inhibitors–Stop the body from producing angiotensin, a hormone that narrows blood vessels.
  • Angiotensin receptor blockers (ARBs)–Stop angiotensin from affecting blood vessels.
  • Calcium channel blockers–Help keep arteries relaxed by preventing calcium from entering heart and artery cells.
  • Central agonists–Help control heart rate and blood flow by blocking signals between the brain and the nervous system.
  • Diuretics–Reduce excess sodium and water in the body.
  • Renin inhibitors–Slow the body’s production of the enzyme renin, which can play a role in high blood pressure.
  • Vasodilators–Prevent artery and vein muscles from narrowing.

How is high blood pressure diagnosed?

High blood pressure is usually diagnosed by a health care professional after a blood pressure screening during an annual checkup. If your blood pressure is usually normal, one high reading is likely nothing to worry about.

Blood pressure can be temporarily raised by lots of different things – such as physical activity, dehydration, what you eat or drink, and even the temperature outside. Just being in the doctor’s office can raise blood pressure.

So before diagnosing high blood pressure, your doctor will likely look at past readings and possibly take another reading. If they’re still not sure, they may recommend additional testing with a home blood pressure monitoring system. And depending on your risk factors or other health conditions, you may be referred to a cardiologist who specializes in cardiovascular diseases (heart-related conditions).

Can high blood pressure be life threatening?

High blood pressure can be dangerous if it’s left untreated. It forces your heart to work harder to get blood out to the rest of your body, and can damage your blood vessels. It can also lead to a number of serious and potentially life-threatening conditions, including:

  • Cardiovascular disease
  • Heart failure
  • Stroke
  • Kidney disease

When to call 911 for high blood pressure

Call 911 immediately if you have extremely high blood pressure or are experiencing warning signs of a heart attack or stroke. Here’s what to watch for:

  • Blood pressure reading of 180 over 120
  • Severe chest pain
  • Severe headache, accompanied by confusion and blurred vision
  • Nausea
  • Significant anxiety
  • Shortness of breath
  • Seizures

Take steps to reach and maintain healthy blood pressure numbers

Left untreated, hypertension puts you at higher risk of heart disease, stroke and other serious conditions. The good news is that there are many ways to lower blood pressure – and it all starts with knowing your blood pressure numbers.

Staying on top of your routine preventive care – specifically annual checkups with a primary care doctor – is one of the best ways to catch blood pressure issues, and identify other risk factors or health conditions earlier, when they’re most treatable.

Also, don’t ignore out-of-the-ordinary symptoms. While high blood pressure often comes without symptoms, other heart-related issues could be at play. Don’t hesitate to get the care you need.

Which is more important systolic or diastolic blood pressure?

Over the years, research has found that both numbers are equally important in monitoring heart health. However, most studies show a greater risk of stroke and heart disease related to higher systolic pressures compared with elevated diastolic pressures.

Is 140 over 70 a good blood pressure?

ideal blood pressure is usually considered to be between 90/60mmHg and 120/80mmHg, while the target for over-80s is below 150/90mmHg (or 145/85mmHg at home)

What do the top and bottom numbers mean in BP?

Systolic blood pressure, the top number, measures the force the heart exerts on the walls of the arteries each time it beats. Diastolic blood pressure, the bottom number, measures the force the heart exerts on the walls of the arteries in between beats.

When should you worry about the bottom number of blood pressure?

Over time, isolated diastolic hypotension can cause heart failure. In fact, it may be one of the most common causes of heart failure. Pay attention to your diastolic number when you have your blood pressure checked. If your lower number is 60 or below, ask a healthcare professional about it.