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The facts about blood pressure
Q. What is high blood pressure?
A. To have high blood pressure, your blood pressure must be consistently equal to or higher than 140/90mmHg over a number of weeks (if you have diabetes or kidney problems a lower level might be used). For more about blood pressure readings, please see How does blood pressure work?
It is worth knowing that you can have high blood pressure if just one of your numbers is consistently higher than it should be. In other words you may be told you have high blood pressure if your maximum or top number (systolic pressure) is consistently equal to or higher than 140 even if your minimum or lower number (diastolic pressure) never reaches 90 and vice versa.
High blood pressure is never diagnosed after just one reading. This is because there can be many reasons why you could have a one-off raised reading. For example, you might have a slightly raised blood pressure because you were feeling tense, had recently had some tea, coffee or cola, or you had been rushing around. Your doctor will usually be looking for a series of high readings, taken over a period of weeks, unless your blood pressure is particularly high to begin with in which case you will receive treatment immediately.
Many people ask if their age makes a difference in the levels used to diagnose high blood pressure. The answer is no: 140/90mmHg is the benchmark for everyone, regardless of whether they are 19 or 89 years old.