The heart is a muscle which pumps blood around the body by expanding and contracting rhythmically. Blood pressure is the force generated by the heart as it contracts and expands. The force is greatest when the heart contracts; this is known as the 'systolic pressure'. It is lowest between beats when the heart relaxes; this is known as the 'diastolic pressure'.Blood pressure naturally rises and falls throughout the day. Pressure will rise during exercise or when you are excited or nervous but will fall when you are at rest or asleep. Sometimes people develop persistently high blood pressure also known as 'hypertension'. This increases the workload of the heart and after a time the extra pressure can cause damage to the heart and blood vessels. This can lead to heart failure, angina, blood vessel disease, kidney disease and stroke.

Blood pressure is measured by a device called a sphygmomanometer. Your doctor or nurse will place a band around your upper arm which will then be inflated until the circulation of blood temporarily stops. Your doctor or nurse will then release the pressure gradually and measure the systolic and diastolic pressures.


It is not fully understood why some people develop high blood pressure while others do not. Most people with high blood pressure have what is known as 'idiopathic' or 'essential hypertension' which means it has no known cause. Contrary to popular belief, high blood pressure is not caused by stress or a nervous disposition. The following factors may however increase the risk of high blood pressure:

  • diet: too much salt in the diet can have a direct effect on blood pressure
  • genetic: high blood pressure can be passed on from generation to generation
  • obesity: being overweight can increase blood pressure
  • exercise: lack of exercise can increase blood pressure
  • medicines: some medicines can raise blood pressure. Such medicines include pain relievers or anti-inflammatory medicines belonging to the non-steroidal anti-inflammatory (NSAID) group, some medicines used to treat ulcers, nasal decongestants and oestrogens including the contraceptive pill and hormone replacement therapy (HRT)
  • medical conditions: people with certain medical conditions such as narrowing of the artery which leads to the kidney, the narrowing of the aorta (the main artery of the body), kidney disease and hormonal disorders such as Conn's syndrome, Cushing's syndrome and phaeochromocytoma may be more at risk of developing high blood pressure
  • drinking heavily: People who drink excessive quantities of alcohol may be more at risk from high blood pressure

How To Avoid High Blood Pressure

  • Cut down on the amount of salt (sodium) that you eat. Do not add salt to your food at the table or during cooking and avoid salty foods. Foods which are high in salt include processed foods such as savoury snacks and crisps, pies, breakfast cereals, bread, gravy mixes and stock cubes, bottled sauces, canned soups, tinned vegetables, meat and yeast extracts, sausages, burgers, tinned meat, smoked or tinned fish, pickles, bacon, ham, gammon and cheese. Increase the amount of potassium in your diet. Potassium counteracts the effects of sodium and can be found in fresh fruit and vegetables in particular spinach, mushrooms, baked beans, bananas, blackcurrants, rhubarb, apricots, fruit juice and dried fruits. Stick to a healthy, low-fat diet. To lose weight, eliminate or cut right down on saturated fat in your diet. Saturated fat is usually solid at room temperature such as butter, lard or dripping. Replace these fats with small amounts of monounsaturated or polyunsaturated fats which are usually liquid or soft at room temperature such as olive oil, rapeseed oil, sunflower oil, nut oils or soya oils. To check the fat content of packaged foods before you buy, look at the fat content under 'nutritional information', this will also tell you what sort of fat the product contains. Avoid cakes, biscuits, chocolate, pastries, savoury snacks, fast food, processed foods, takeaways, oils (except fish oils), spreads, butter, meat products and full-fat dairy produce. Remove skin from poultry, trim off excess fat from meat and skim fat from casseroles. Do not add fat to foods during cooking. Grill, steam, boil, poach or bake food instead of frying or roasting it. Instead of frying, try using a dry griddle or a non-stick pan. Eat plenty of fibre. Fibre can be found in fresh fruit and vegetables, wholemeal bread, cereals, wholemeal pasta and pulses. Take some form of exercise each day such as a brisk walk, swimming or cycling. Do not smoke. Smoking increases the risk of blood vessel disease which increases the risk of a heart attack or stroke.
  • Do not drink more than three units of alcohol per day if you are a man or two units if you are a woman. One unit is equivalent to one glass of wine, one measure of a spirit or half a pint of ordinary strength beer, lager or cider. If you do drink, your alcohol intake should be spread evenly throughout the week. Do not drink your week's allowance on one night!


If lifestyle changes do not help, medicines are available to lower blood pressure.

  • ACE inhibitors prevent the formation of angiotensin II, a naturally occurring substance in the body that causes the blood vessels to contract. ACE inhibitors help to lower the blood pressure by expanding the blood vesselsalpha-blockers block the effects of chemicals in the body. This expands the blood vessels and allows blood to flow freelyangiotensin II receptor antagonists block the effects of Angiotensin II, causing the blood vessels to relaxbeta blockers block the transmission of chemical messengers in the body. This slows the rate and reduces the strength of the heartbeat, reducing its need for blood and oxygencalcium-channel blockers help to lower blood pressure by expanding the blood vessels allowing the blood to flow more freelydiuretics or 'water tablets' lower blood pressure by removing excess water from the bloodstream, reducing the volume of circulating blood.
  • vasodilators help to lower blood pressure by expanding the blood vessels allowing the blood to flow more freely

When To See A Doctor

If you ever experience chest pain, numbness or weakness of the arms and legs, visual disturbances or speech problems, tell your doctor at once.

Additional Information

For additional information about high blood pressure, contact the British Heart Foundation, 14 Fitzhardinge Street, London W1H 4DH. Telephone: 0171 935 0185. Or visit their website at