When you get upset you might feel your heart pounding, your temperature rising, your face reddening and you may even feel like you have steam coming out of your ears (if you’re a cartoon character, that is). The reason for the “blowing a gasket” cliche? All that pressure building up inside—and for real humans, that’s your blood pressure.
Unfortunately, while it’s easy to tell when Bugs Bunny has high blood pressure, it’s much harder to see when humans get hypertensive. That’s why it’s crucial for your overall health to know how to read your blood pressure.
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Why it’s vital that you know this vital sign
“Your blood pressure is considered a key ‘vital sign‘ because it is one of the most important indicators of heart health, showing your risk for heart disease, heart failure, and heart attacks,” says Yu-Ming Ni, MD, cardiologist at MemorialCare Heart and Vascular Institute at Orange Coast Medical Center in Fountain Valley, California. “But the symptoms of high blood pressure can be silent or easily mistaken for other things, so unless you’re measuring yours regularly then you may miss this vital warning sign.”
What is blood pressure?
“Blood pressure” refers to the force exerted by your blood against the walls of your blood vessels, particularly the arteries, as the heart pumps it through your body. If blood pressure goes too low or too high it can be fatal, so it’s important to know your sweet spot and keep yours out of the danger zones.
Blood pressure is measured in millimeters of mercury (mmHg) because old-fashioned blood pressure measuring instruments used mercury-filled columns. We no longer use the mercury, but we did keep the standard of measurement.
Normal blood pressure: around 120/80 mmHg
Elevated blood pressure: 120-129/less than 80 mmHg
Hypertension (high blood pressure): 130/80 mmHg or higher
Hypotension (low blood pressure): below 90/60 mmHg
How to read blood pressure
What do those blood pressure numbers mean?
Blood pressure is made up of two numbers (for example, 120/80 mmHg).
The top number, called the systolic pressure, measures the pressure when the heart contracts and pumps blood into the arteries.
The bottom number, known as the diastolic pressure, measures the pressure when the heart is at rest between beats.
Here’s how often you should measure your blood pressure
“I recommend most patients take their blood pressure one to two times per week,” Dr. Ni says. “But you should take it daily if you have a serious heart condition or are adjusting medications.”
The key to monitoring your blood pressure? “Write it down,” Dr. Ni says. “I cannot stress this enough. We look at blood pressure over time to see if there are changes so you need to be tracking it.”
You can use a paper journal, a phone app, a computer spreadsheet, or the electronic record on your blood pressure monitor (if it has that feature).
How to take your blood pressure at home
You likely don’t see your doctor that often, and not only can you measure your own blood pressure at home—but you should. “You’re more likely to get an accurate reading at home, as some people get ‘white coat hypertension,’ meaning that being at the doctor’s makes them anxious which raises their blood pressure,” Dr. Ni says. “Measuring your blood pressure at home allows you to be more relaxed and consistent—two key things to getting an accurate measurement.”
- Step 1 to measuring your blood pressure at home: Get an automatic blood pressure cuff. (That link takes you to a verified product with an average 4.7-star rating from more than 20,000 Amazon shoppers.)
- You can use a manual cuff and stethoscope, but it’s easier and more accurate to use an automated blood pressure cuff, Dr. Ni says. You can get these at any drugstore, big box store, or off the internet. They range in price from $15 to $200. “The simple ones are as accurate as the pricier models, they just don’t come with all the bells and whistles,” he explains. This automated blood pressure cuff gets 4.6 stars and is less than $30 at press time.)
- Step 2: Place the cuff around your arm, following the directions on the cuff. (Most have an arrow showing you which direction to place them.)
- Step 3: Take a few minutes to sit or lay down, breathe deeply and relax. Then press the start button. Hold still while the machine does it’s thing.
- Step 4: Save or record the numbers.
Cardiologist-approved tips for taking your blood pressure at home
We asked Dr. Ni to share his pro tips to get the best, most accurate reading when taking your own blood pressure. Measure your blood pressure:
At the same time of day on the same day every week. For instance, take your blood pressure 30 minutes after waking every Sunday morning.
Before taking any medications.
Before eating or drinking, especially anything with caffeine, like coffee or tea. Water is fine, and you should be normally hydrated.
Before checking the news, your text messages, or anything else that might make you feel anxious.
While sitting in a comfortable chair with both feet on the ground. No crossing your legs!
Resting your arm on a table or arm rest at the same level as your heart.
It’s normal for your blood pressure numbers to fluctuate
“One thing that often makes people anxious about taking their own blood pressure is how much the numbers can change even in a single day, but fluctuations are normal,” Dr. Ni says.
Hydration is often the main culprit in blood pressure fluctuations, he explains, as water makes up the bulk of your blood volume. So being dehydrated (or, less commonly, overhydrated) can really affect your numbers.
Other reasons blood pressure readings can vary throughout the day include physical activity, stress, medications, emotions, meal times, and overall health.
When to call a doctor
If your blood pressure readings are high consistently for a few weeks, give your doctor a call. If they go into the extreme high range (over 180 on top and over 100 on bottom) and you are having any symptoms of a heart attack, like chest pain, trouble breathing, nausea, dizziness, chest pressure, or pain in your left arm—this is a true emergency and you should go directly to the nearest emergency department.
“If you know you have high blood pressure or that you have a strong family history of heart disease, it’s important to get regular checkups with your doctor in addition to monitoring your blood pressure at home,” Dr. Ni says, adding that your doctor will discuss which lifestyle and medication treatments are right for you.
Maintaining a healthy blood pressure
Anything that is good for your heart health is good for your blood pressure, Dr. Ni says. Start by getting 30 minutes of daily exercise, maintaining a healthy weight, setting yourself up to get seven to eight hours of sleep each night, strengthening close relationships, and finding ways to manage your stress. One way to limit stress? Limit your screen time—using your phone for this many hours a day causes high blood pressure, according to a new study.
Also up your nutrition game by eating a heart-healthy diet, limiting processed foods and sugary drinks, keeping your salt and alcohol intake moderate, and talk to your doc about adding these supplements shown to lower blood pressure.
“Knowing your numbers is really important to your health, we call high blood pressure the ‘silent killer’ because it often has no warning signs or symptoms, and you may not even realize you have it unless you are regularly measuring it,” he says. “Do not ignore high blood pressure.”
To learn more about heart disease, how to prevent it, treat it, and recover from it, check out these groups.