Cardiologist shares what not to do before taking your blood pressure

Having high blood pressure, also known as hypertension, is the leading risk factor for disability, dementia and early death worldwide.

Nearly one in two adults in the U.S. has hypertension. Many people check their numbers at home, but making one simple mistake can throw off the readings.

Cardiologist Puxiao Cen with Advent Health says there are many rules to follow.

"You should be, not only talking for five minutes before checking blood pressure, but also within the half hour, no smoking, no exercising and no caffeine," said Cen.

All of those actions can cause your blood pressure reading to be higher than it actually is, which can lead doctors to overprescribe medications and result in low blood pressure. These aren't the only factors that can affect readings.

"I remember 30 years ago when I was a resident, There was a patient keep having very fast heart rate and blood pressure, and he's quadriplegic, and we had no idea until we found out that we should empty the bladder for him and the blood pressure and heart rate is perfect," said Cen.

When checking blood pressure, positioning matters.

"Their feet should be flat on the ground and back supported with a chair, and if it's using an arm cuff, the arm should be at the level of the right atrium, which is the middle of the sternum," said Cen.

An arm resting in the lap can raise the reading by 3.9/4 mmHg, and a dangling arm can raise it even more.

Lastly, avoid taking your blood pressure too many times in one sitting.

"The blood pressure cuff can stimulate vascular resistance and you can get higher and higher blood pressure reading," said Cen.