High blood pressure is also known as hypertension. Blood pressure is the amount of force exerted against the walls of the arteries as blood flows through them and extreme fluctuations in the systolic reading may be bad.
Having consistently high blood pressure increases the risk of stroke, heart attack or even death, researchers said. The systolic blood pressure indicates how much pressure is being exerted by the blood against the arterial walls.
According to the American Heart Association, a normal systolic blood pressure is less than 120 while high blood pressure is categorised as above 140.
"Blood pressure is one of those numbers we encourage people to keep track of, as it's one indicator of your heart-health," said lead investigator Brian Clements, an internal medicine specialist with the Intermountain Medical Centre Heart Institute in Utah.
"If you allow your blood pressure to remain uncontrolled for any period of time, or notice big changes in your blood pressure between doctor visits, you increase your risk of stroke, heart attack, kidney or heart failure or even death," Clements added.
For the study, to be presented at the 2017 American Heart Association Scientific Sessions in California, the team examined visit-to-visit variability of systolic blood pressure in 10,903 patients.
Patients should do everything they can to control their blood pressure on a regular basis, Clements said.
"Eat healthy foods, exercise regularly, and if your doctor has prescribed you medication for blood pressure, be sure to take them consistently.
"Because any time your blood pressure is out of control, you're at higher risk of injury or death," Clements said.