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Classification and external resources
Automated arm blood pressure meter showing arterial hypertension (shown a systolic blood pressure 158 mmHg, diastolic blood pressure 99 mmHg and heart rate of 80 beats per minute)
eMedicinemed/1106 ped/1097 emerg/267

Hypertension or high blood pressure, is a chronic medical condition in which the blood pressure in the arteries is higher than it should be. This requires the heart to work harder than normal to circulate blood through the blood vessels.

Blood Pressure

The pressure in the arteries changes depending on what the heart is doing. When the heart contracts, pumping blood into the arteries, the pressure increases. When the heart relaxes, the pressure decreases. When blood pressure is measured, the highest pressure (when the heart is contracting) is called systole, and the lowest pressure (when the heart is relaxing) is called diastole.

Blood pressure is measured with a number followed by “mmHg”, which stands for “millimetres of mercury”. Blood pressure is written with the highest pressure first, followed by the lowest pressure. For example, someone whose highest blood pressure is 140 mmHg and whose lowest blood pressure is 90 mmHg would have their blood pressure written as 140/90.

Types of Hypertension

Hypertension comes in two main types, called “primary” and “secondary”. Primary hypertension means that the hypertension is not caused by any other disease of the body. Secondary hypertension means that the hypertension is caused by another disease. In most cases hypertension is primary (90-95%), with only a very small amount being secondary (5-10%).

Problems Caused by Hypertension

Hypertension can lead to diseases such as heart attack, stroke, and kidney disease. To stay healthy, most people should try to keep their blood pressure below 140/90 mmHg[1]


Lifestyle changes

Hypertension can often be fixed with changes in diet or lifestyle. The following are recommended by the 2004 British Hypertension Society guidelines[2]:

  • Lose weight if overweight or obese
  • Exercise regularly
  • Reduce dietary salt intake
  • Limit alcohol consumption
  • Consume a diet rich in fruit and vegetables


If lifestyle changes fail, then medications are often required. The medications which are used depend on the other medical conditions which the person has. Examples of medications include:

  • Diuretics, which increase urination to get rid of excess fluid
  • Beta-blockers, which slow down the heart rate
  • ACE inhibitors, which reduce the tightness of the arteries


Even small reductions in blood pressure can have a large effect on one's health. For example, reducing blood pressure by 5 mmHg (e.g. from 150/100 to 145/95 mmHg) can decrease the risk of stroke by 34% and of heart disease by 21%.[3]


  1. Arguedas, JA; Perez, MI; Wright, JM (Jul 8, 2009). Arguedas, Jose Agustin. ed. "Treatment blood pressure targets for hypertension". Cochrane Database of Systematic Reviews (3): CD004349. doi:10.1002/14651858.CD004349.pub2 . PMID 19588353 .
  2. Williams, B; Poulter, NR, Brown, MJ, Davis, M, McInnes, GT, Potter, JF, Sever, PS, McG Thom, S, British Hypertension, Society (March 2004). "Guidelines for management of hypertension: report of the fourth working party of the British Hypertension Society, 2004-BHS IV". Journal of Human Hypertension 18 (3): 139–85. doi:10.1038/sj.jhh.1001683. PMID 14973512
  3. Law M, Wald N, Morris J (2003). "Lowering blood pressure to prevent myocardial infarction and stroke: a new preventive strategy". Health Technol Assess 7 (31): 1–94. PMID 14604498.