You probably have high blood pressure (hypertension) if your blood pressure readings are consistently 140 over 90, or higher, over a number of weeks.
You may also have high blood pressure if just one of the numbers is higher than it should be over a number of weeks.
If you have high blood pressure, this higher pressure puts extra strain on your heart and blood vessels. Over time, this extra strain increases your risk of a heart attack or stroke.
High blood pressure can also cause heart and kidney disease, and is closely linked to some forms of dementia.
High blood pressure usually has no signs or symptoms, so the only way to know if you have high blood pressure is to have yours measured. However, a single high reading does not necessarily mean you have high blood pressure. Many things can affect your blood pressure through the day, so your doctor will take a number of blood pressure readings to see that it stays high over time.
Occasionally people with very high blood pressure say they experience headaches, but it is best to visit your GP if you are concerned about symptoms.