Whether measuring at home or at a doctor's office, your blood pressure should be taken in both arms simultaneously, if possible. A blood pressure difference of less than 5 mmHg between the left and right arm is considered normal.
Single-arm measurements, compared to double-arm measurements, may underestimate the prevalence of hypertension. However, if double-arm measurements are unavailable, right arm is preferred for measurement of BP, especially in women.
Higher pressures are more frequent in the right arm and range in most individuals from 10 to 20 mmHg or greater in systole, and to a similar extent but less often in diastole. A BP difference between the left and right arms—even when large—is statistically a normal variant and need not necessarily cause concern.
It's also a good idea to have your blood pressure measured in both arms at least once, since the reading in one arm (usually the right) may be higher than that in the left.
International blood pressure guidelines recommend taking the blood pressure in both arms, at least at the initial patient visit. But with new research, many physicians believe that taking the blood pressure in both arms every time is an easy way to spot health issues early.
Small differences in blood pressure readings between the right and left arm are normal. But large ones suggest the presence of artery-clogging plaque in the vessel that supplies blood to the arm with higher blood pressure.
In the right arm, the sub clavian artery is 90 degrees from the aorta, so the pressure is a little less. In the left hand, the sub clavian artery from the aorta has a better angle, around 170 degrees, so it is more trusted as a source of measuring BP and works for most people.
Usually, blood pressure starts to rise a few hours before a person wakes up. It continues to rise during the day, peaking in midday. Blood pressure typically drops in the late afternoon and evening. Blood pressure is usually lower at night while sleeping.
Take it first in the morning before eating or taking any medications. Take it again in the evening. Each time you measure, take two or three readings to make sure your results are the same. Your health care provider might recommend taking your blood pressure at the same times each day.
Everyone's blood pressure rises and falls many times during the course of a single day, sometimes even within minutes. Many factors contribute to these changes, including physical activity, emotion, body position, diet (especially salt and alcohol intake), and sleep deprivation.
A cuff that is too snug or too loose on the mid-upper arm can lead to greatly exaggerated blood pressure measurements, results of a community-based study show.
It's actually quite normal. A difference of more than 10 points, though, could suggest trouble. In younger people, side-to-side differences in blood pressure can occur when a muscle or something else compresses an artery supplying the arm, or by a structural problem that prevents smooth blood flow through an artery.
Normal blood pressure for most adults is defined as a systolic pressure of less than 120 and a diastolic pressure of less than 80.
Blood pressure should be checked while seated after a few minutes of rest. Take at least two readings a minute apart each time. Wait at least 30 minutes after having caffeine, alcohol, smoking, or exercising before taking your blood pressure.
Still, you can make lifestyle changes to bring your blood pressure down. Something as simple as keeping yourself hydrated by drinking six to eight glasses of water every day improves blood pressure. Water makes up 73% of the human heart,¹ so no other liquid is better at controlling blood pressure.
Call 911 or emergency medical services if your blood pressure is 180/120 mm Hg or greater and you have chest pain, shortness of breath, or symptoms of stroke. Stroke symptoms include numbness or tingling, trouble speaking, or changes in vision.
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.
Walking lowers systolic blood pressure by 4.11 mm Hg (95% CI, 3.01 to 5.22 mm Hg). It lowers diastolic blood pressure by 1.79 mm Hg (95% CI, 1.07 to 2.51 mm Hg) and resting heart rate by 2.76 beats per minute (bpm; 95% CI, 0.95 to 4.57 bpm).
“It's actually quite normal to have variation in blood pressure readings, even within a few minutes,” says Marjorie Willett, nurse practitioner at Aurora Lakeland Medical Center. “Factors that may create changes include physical activity, emotion, diet (especially salt and alcohol intake), and sleep deprivation.”
Blood pressure readings taken at home were consistent with ABPM. Blood pressure readings based on follow-up clinic visits were significantly lower for the systolic measure, leading to over half of the people with hypertension based on ABPM being missed.
Acute meal ingestion, caffeine or nicotine use can all affect BP readings, leading to errors in measurement accuracy. If the patient has a full bladder, that can lead to an error in systolic BP of up to 33 mm Hg, and the white-coat effect can have an error of up to 26 mm Hg.