
Two-arm blood pressure difference is a very common condition when measuring blood pressure. Since then, many people wonder if this difference is due to physiology or pathology? Which arm should take the blood pressure readings accurately. Let’s find out with Dr. Nguyen Lam Giang through the following article!
Blood pressure readings
Before learning about the difference in blood pressure between two arms, let’s refer to the basic information about blood pressure readings. The only way to know your blood pressure is to check it with a sphygmomanometer. Understanding the results is the key to better blood pressure control.
Normal blood pressure readings (physiology of the body) when:
- Systolic blood pressure is between 90 and no more than 130 mmHg.
- Diastolic blood pressure is between 60 and no more than 90 mmHg.

Blood pressure measurement is usually in the arm
Then why measure blood pressure in the arm? Think of the body’s vascular system as a fluid reservoir. Accordingly, the pressure of the liquid will increase with the depth of the vessel. So the blood in the calf is deeper than the blood in the arm, so the pressure will be higher. Blood pressure is usually measured at the arm position because the arm is about the same height as the heart. When measuring, the person being measured should put his arm on the table and at chest level for a better level of accuracy.
What’s wrong with the blood pressure difference between the two arms?
Why is blood pressure different in both arms?
According to cardiologists, blood pressure in both arms is slightly different or equal. This is a common practice in normal people, without any blood pressure disease. Under normal physiological circumstances, blood pressure in both arms varies and the difference is usually not more than 10 mmHg.
If the blood pressure in both arms is uneven and the difference is higher than 10 mmHg, it means that the body is in a disorder. Chances are low blood pressure has decreased blood flow. At this point, the patient needs to be examined by a specialist to determine the cause of the abnormality.
Why is right arm blood pressure higher than left arm?
Centuries ago, scientists demonstrated that the difference in blood pressure between the arms was linked to poorer health. The greater the blood pressure difference between the arms, the higher the cardiovascular risk. Therefore, measuring blood pressure in both arms is really important.
Normal cases
Theoretically, there shouldn’t be a big difference in blood pressure readings in the right and left arms. However, in reality, the blood pressure of the right arm is slightly higher than that of the left. Or there are cases where the left arm’s blood pressure is slightly higher than the right one. The reason is because blood pressure is affected by surrounding circumstances. For example, a tight or loose wristband. Or the psychology of the person being measured blood pressure changes when measuring each arm.

Anatomy of the brachiocephalic artery
On the other hand, due to the anatomical structure, it is common for the right arm to have higher blood pressure than the left hand. This is because the right arterial system originates from the brachiocephalic artery. This is closer to the heart than the arteries in the left hand. Therefore, when the heart contracts, the right-hand artery will have a slightly higher pressure. From there, the blood pressure is also higher than on the left side.
Medical cases
In unusual cases, the blood pressure of the right arm will be more than 10 mmHg higher than the left arm. The pathological mechanism is because the arterial system in the right hand is narrowed due to atherosclerosis, trauma, etc. Since then, the peripheral resistance will increase, leading to higher blood pressure than the left hand.

Narrowing of blood vessels due to atherosclerosis
Which arm blood pressure measurement is correct?
Advice from experts when blood pressure in both arms is uneven
So which arm blood pressure measurement is correct when there is a difference in blood pressure between the two arms? Because the blood pressure in the two hands is different, many people wonder which arm should take the blood pressure results. However, specialists recommend that people measure their blood pressure in both arms a few times.
Situations that can occur when blood pressure in both arms is different
If the blood pressure in the left arm is higher or equal to the right arm, continue to measure the blood pressure in the left arm at the next time. If the blood pressure readings in the right arm is higher than the left arm, continue to measure the blood pressure in this arm. Thus, the uniformity in the measurement process will bring reliable results. And different blood pressure measurements will have a higher accuracy.

Blood pressure should be measured in both arms
If the high and low blood pressure in the arms changes alternately, you should recheck the blood pressure measurement. The purpose is to make sure that you have followed the instructions for measuring your blood pressure correctly. If you repeat the measurement many times and still see a large difference in blood pressure between the two arms, you should see a doctor. Because this can be a sign of some dangerous disease.
With the information that the article has provided, hopefully readers will better understand the problem of blood pressure difference in both arms. From there, follow the recommendations of the experts. Also, go to the doctor as soon as you notice any abnormality.

John Alen was born in 1971 and is a doctor in the healthcare and psychology fields with many years of experience. He is currently working at easyhealthylive.com, a leading health and psychology blog. Having studied at Y1 National Medical University named after IM Sechenov, John Alen is using his knowledge and experience to help improve the physical and mental health of people in the United States.