Blood pressure
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Blood pressure, hypertension
Cardiovascular system
When the heart contracts and forces blood into the arteries it creates a pressure called ‘blood pressure’. Every living person has a blood pressure, and it is this pressure that allows the blood to circulate around the body. Blood pressure varies throughout the day, going up during times of activity and going down when relaxed. Hypertension is the name given to the condition when the blood pressure is persistently high. The high pressure puts an excess strain on the heart, blood vessels, kidneys and other organs and increases the risk of developing heart attacks, strokes and kidney damage.

Blood pressure is measured usually using an instrument called a sphygmomanometer or by an electronic device. These instruments allow two readings to be taken of the pressure of the blood in the arteries – one when the heart contracts, called the systolic pressure and one when the heart relaxes, called the diastolic pressure. The pressure is measured in millimetres of mercury, written as mmHg (Hg is the chemical symbol for mercury), and is recorded as systolic pressure/diastolic pressure. The ideal pressure is defined as a systolic pressure of 120 mmHg and a diastolic pressure of 80 mmHg, which is written as 120/80. At or below this level there is a much lower risk of heart disease and stroke. Hypertension or high blood pressure is defined as a systolic pressure of 140 mmHg or greater, or a diastolic pressure of 90 mmHg or greater, which is written as 140/90.

Even though 140/90 is a level at which someone is regarded as having hypertension, it is important to keep blood pressure at, or below 120/80, because the higher the blood pressure, the higher the risk of health problems. For example, a blood pressure of 135/85 may be “normal” but someone with this reading is twice as likely to have a heart attack or stroke as someone with a reading of 115/75.

As blood pressure is influenced by a number of factors, a diagnosis of hypertension should only be made after two readings have been taken on at least two separate occasions with the person sitting down and relaxed.
Hypertension is very common, affecting up to 1 in 4 of the adult population of the UK. A small number of people have what is called secondary hypertension, which means that there is an underlying cause of their high blood pressure. However, for most people there is no definite cause of their high blood pressure. Doctors call this primary or essential hypertension.

Some groups of people with certain lifestyles or hereditary factors are more likely to develop hypertension. These include:
  • Those with a family history of high blood pressure
  • Men – men are more likely to develop hypertension than women
  • Ethnicity – black African, Caribbean and people from the Indian sub-continent are more likely to develop hypertension
  • Those with an unhealthy lifestyle - people who are overweight, eat too much salt and not enough fruits and vegetables, take little exercise, drink too much alcohol and caffeine or smoke are more likely to have high blood pressure
  • Older people – blood pressure tends to rise with age
  • Those who suffer from stress
Usually the only way to know if someone has high blood pressure is to have it measured. Most people cannot tell if their blood pressure is high any other way. It is recommended that all adults should have their blood pressure measured at least every 5 years. Those with high normal values or with other risk factors such as diabetes or smoking should be measured at least annually.
High blood pressure is not usually something that can be cured, but it can be managed successfully. Medications used to lower blood pressure are known as antihypertensives. There are a large number of different types of antihyptensives, all working in different ways within the body to lower blood pressure. Some of the most commonly used antihypertensives include ACE inhibitors (eg enalapril, lisinopril), A2 antagonists (eg losartan, valsartan), beta-blockers (eg propranolol, timolol), calcium antagonists (eg amlodipine, nifedipine) and diuretics (eg bendroflumethiazide).

A doctor will decide what kind of treatment to use by assessing the patient’s previous medical history and the presence of other risk factors. Often, two or more antihypetensives will be used together to improve the way that they lower blood pressure.
When to consult your pharmacist
Many pharmacists now provide a blood pressure measuring service. You can simply call into your pharmacy to have your blood pressure checked if you are concerned about your blood pressure or simply want to know what it is. If you have risk factors for high blood pressure such as being overweight, you smoke and take very little exercise you should have your blood pressure checked at least once per year. If your pharmacist finds that your blood pressure is high, you will be advised to see your doctor.

Always tell your pharmacist if you are taking any antihypertensive medication. Many of these drugs have side effects and the pharmacist will be able to advise you on the correct way to take the medicine to help reduce these side effects. Your pharmacist also needs to know the type of antihypertensive medication you are taking to make sure that it does not interact with any products that may be sold to you without a prescription to treat other illnesses.

Your pharmacist will also be able to advise you on making lifestyle changes, for example giving up smoking, which will help lower your blood pressure.
When to consult your doctor
If you have your blood pressure measured and it is above 140/90 then you should see your practice nurse or your doctor to have it checked again. If after several readings your high blood pressure is confirmed, your doctor will advise lifestyle changes such as diet and exercise, and may prescribe antihypertensive medication that is most suited to you.
Living with high blood pressure
Although you may feel perfectly well and unaware that your blood pressure is raised, it is important that you listen to your doctor’s, nurse’s or pharmacist’s advice to reduce the risk of your having a heart attack, stroke or suffering from kidney damage. It is important not to ignore high blood pressure. The complications of uncontrolled high blood pressure cause more deaths and severe disability from heart attacks, stroke and kidney damage than any other disease.

The aim of treatment is to get your blood pressure down to 140/85 or even lower if you have other risk factors such as angina, diabetes or have had a previous heart attack. Once your blood pressure comes down, so does your risk of heart attacks and stroke.

Some people may be able get their blood pressure down by life style changes alone, without the need for antihypertensive medication. Lifestyle changes include stopping smoking, losing weight, cutting down the level of salt and saturated fats in the diet, eating at least 5 portions of fruit and vegetables each day, taking 30 minutes of active daily exercise and limiting alcohol and caffeine intake. If you are taking an oestrogen-containing oral contraceptives you should consider changing to a progestogen-only contraceptive. Learn to relax and try not to get upset or stressed by everyday events.

Most people will also need to take antihypertensive medication to lower blood pressure.

If antihypertensive medication has been prescribed for you, it is important that you follow the dosage instructions. Some patients decide not to take antihypertensive medication because they do not have any symptoms of high blood pressure. However, it is important that antihypertensive medication is taken all of the time. Never stop taking your antihypertensive medication suddenly as this could cause your blood pressure to rise to dangerously high levels.

Have your blood pressure measured regularly to make sure that you have reached and are maintaining the target levels.
Useful Tips
    • Give up smoking - see give up smoking section
    • Cut down on the amount of salt you eat - no more than 5 grams a day.
    • Don't add salt to food at the table or in cooking
    • Avoid eating salty, processed foods
    • Keep alcohol intake below the recommended limits
    • If overweight try to shed a few pounds
    • Eat a diet low in saturated fat and high in fibre - see Diet section
    • Take regular exercise
Further information
The Blood Pressure Association is the UK charity dedicated to lowering the nation's blood pressure to prevent disability and death from stroke and heart disease. The Blood Pressure Association has a range of information materials, web site and membership scheme to help you take control of your condition.

Blood Pressure Association
60 Cranmer Terrace
SW17 0QS
Tel: 020 8772 4994
Information line: 0845 241 0989

Reviewed on 24 November 2010