Extreme swings in systolic blood pressure may be just as dangerous as having high blood pressure all the time. This fact is concluded in a new study from the Intermountain Medical Centre Heart Institute in Salt Lake City.
In the study, researchers examined the medical records of 10,903 patients. Patients who had seven blood pressure measurements between 2007 and 2011 were included. After the last measurement, patients were followed for five years, during which researchers looked at all causes of mortality.
The study concludes that patients whose systolic blood pressure varied by as much as 30 or 40 between doctor visits over a longer period of time were more likely to die from high blood pressure complications than those who did not show such extreme blood pressure swings.
According to Dr. Clements, lead investigator of the study, the results of this study show how important it is to control your blood pressure on a regular basis. If you allow your blood pressure to be 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. 
So you know what to do: make sure to check your blood pressure regularly!