How do I know if I have high blood pressure?

Your doctor can easily measure your blood pressure and these days there are many home measurement kits available. It is probably best at first to visit your doctor who will be able to give you the correct advice based on your results.

Blood pressure is usually measured with a small, portable instrument called a blood pressure cuff. The cuff is placed around the upper arm and inflated with an air pump. The cuff can measure the pressure of the blood pushing against it through the vessel walls. When you have your blood pressure taken you will be told 2 numbers, the first larger than the second, for example 120/80 (“120 over 80”). The numbers are given in millimetres of mercury, or mmHg, which is a simple measurement of pressure. The first number refers to the pressure of your blood at the moment when your heart beats and is called the systolic blood pressure. When the heart beats, blood pressure increases for a moment, a bit like if you were to squeeze a balloon the pressure inside would go up. The second number is the pressure in between heartbeats when the heart is relaxed. This is called the diastolic blood pressure and is more like the pressure in the balloon when untouched.

Some people experience high blood pressure only when they visit the doctor's office. This condition is called "white-coat hypertension" and is usually caused by the nerves of visiting the doctor. If your doctor suspects this, he/she may ask you to monitor your blood pressure at home or to wear a device called an ambulatory blood pressure monitor for 24 hours. This device will take readings of your blood pressure every 30 minutes and give the doctor an average.

The definition of what is normal and high blood pressure varies between country and the various guidelines that doctors use. But in general, normal blood pressure is below 120/80; blood pressure between 120/80 and 139/89 is called pre–hypertension, which means there is a risk of hypertension developing, and a blood pressure of 140/90 or above is usually considered high.