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International Society of Hypertension

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FAQ's on hypertension and its treatment

We hope that the following information will help by providing answers to some common questions that you may have with regard to hypertension (high blood pressure) and encourage you to take an active and positive role in managing and controlling this condition.

All our information is designed to complement and not substitute the advice you get from your health professional. Please do not change the treatment of your blood pressure without first talking to your health professional.

1. What is blood pressure?

Blood pressure is simply the physical pressure of blood in the blood vessels. It is similar to the concept of air pressure in a car tyre.

2. What do the numbers mean?

A common blood pressure might be 120/80 (said as '120 over 80'). These values are quoted in units known as millimetres of mercury (mmHg).

There are 2 numbers because the blood pressure varies with the heartbeat. The higher pressure (120) represents the pressure in the arteries when the heart beats, pumping blood into the arteries. This pressure is called systolic pressure. The lower pressure (80) represents the pressure in the arteries when the heart is relaxed between beats. This pressure is called diastolic pressure.

3. Does blood pressure change?

Blood pressure can be quite variable, even in the same person.

Blood pressure goes up and down with different normal daily activities. For example, exercise, changes in posture and even talking changes blood pressure.

Blood pressure tends to be higher during the day than at night and higher in the winter than in the summer.

Blood pressure also rises when we grow older, particularly systolic blood pressure. Before adulthood, blood pressure rises in parallel with height.

In adult years, weight and blood pressure are closely related. When weight goes up, blood pressure tends to go up and we can lower blood pressure by losing weight.

4. What is high blood pressure?

Blood pressures differ between individuals. Some people have low, some average and some high blood pressure levels.

There are various definitions of high blood pressure, which is also known as hypertension, but most doctors consider blood pressures of 140/90 and greater to be high.

The precise values that doctors might interpret as high blood pressure depend to an extent on individual circumstances. For example, in patients with diabetes, the definition of hypertension is considered by some to be pressures greater than 130/80.

The definition of hypertension is used by doctors to help decide which patients would benefit from medical (lifestyle and drug) treatment to lower pressure.

The definitions depend on the balance of risk of not lowering blood pressure (heart attack and stroke, etc) versus the risks of treatment (drug side effects, etc).

This explains why hypertension is defined at lower blood pressure levels in diabetic subjects. For the same blood pressure, cardiovascular complications (that is damage to the heart, blood vessels and brain) are more likely in diabetics and blood pressure reduction offers benefit even when a diabetic's blood pressure is not as high as regular definitions of hypertension.

5. How common is high blood pressure?

Approximately 4 in 10 adults over age 25 have hypertension and in many countries another 1 in 5 have prehypertension.

An estimated 9/10 adults living to 80 years of age will develop hypertension.

One half of blood pressure related disease occurs in people with higher levels of blood pressure even within the normal range.

6. Why is blood pressure important?

Blood pressure is important because it is the driving force for blood to travel around the body to deliver fresh blood with oxygen and nutrients to the organs of the body.

However, high blood pressure is important because it leads to increased risk of serious cardiovascular disease, with complications such as heart attack, heart failure, stroke, kidney failure and blindness.

7. What causes high blood pressure?

For the vast majority of people with high blood pressure no precise explanation is ever found. For this reason, such cases are said to have 'essential' hypertension.

These cases are likely to result from a range of factors that could be broadly grouped into genetic and environmental (lifestyle) factors that work together to raise blood pressure.

Because genes and environmental are shared within families, it is not uncommon for people with high blood pressure to know of relatives with the same condition.

In a minority of cases of hypertension (less than about 5%) a precise cause can be identified. These include hormonal imbalances and kidney diseases that can result from genetic problems, occasionally tumours (usually benign) and blood vessel narrowing. Doctors are trained to look for signs of these specific conditions, as they are often curable.

8. Who gets high blood pressure?

High blood pressure is more common is older age groups and in people with a family history of hypertension. It is also more frequent in those who are overweight. However, high blood pressure can affect young thin people with no family history, so no one should consider himself or herself immune from high blood pressure.

9. Does high blood pressure need to be treated?

It is the goal of good clinical practice to reduce high levels of pressure wherever possible in order to reduce the risk of complications such as heart attack and stroke.

Changes to lifestyle such as weight loss, reduced salt intake, reduced alcohol consumption or exercise are often the first line of treatment. If these approaches don't return blood pressure to acceptable levels then drug treatment is usually required.

10. How do I know if I've got high blood pressure?

The truth is you cannot know your blood pressure unless you have it measured and every adult should know his or her blood pressure.

Although headaches and nose bleeds can be the result of very high blood pressure, there are many more innocent causes for these common ailments.

11. Whom should I contact to find out more?

Your local doctor is the best-qualified person to ask about blood pressure.

12. How can I lower the risk of developing high blood pressure?

A healthy lifestyle and a sensible diet are important. One of the most important things is to keep weight under control. Less weight means lower blood pressure, and it also means less diabetes, less stress on muscles and joints and less stress on the heart.

13. Will hypertension go away without treatment?

It is rare for hypertension to disappear by itself. The general rule is that blood pressure gets higher with time and the risk of complications goes up also.

14. Can high blood pressure be cured?

Although not 'cured' as such, modern therapeutic approaches to blood pressure are very effective and generally very safe. However, if treatment is stopped the high blood pressure usually returns reasonably quickly.

15. What is a dangerously high blood pressure - how high does it have to be before you have a stroke or a heart attack?

Any degree of high blood pressure is associated with increased risk of stroke and heart attack, but the higher the pressure, the higher the risks.

If blood pressure is persistently 140/90 and greater, then some form of treatment is required, although in the first instance this might be adjustments to lifestyle, such as diet and exercise.

However, if the blood pressure is repeatedly greater than 160/110, then there is usually a need to begin drug treatment immediately, rather than relying on lifestyle changes alone.

Sustained blood pressures of over 200/120 are considered potentially dangerous and if associated with for example visual trouble or heart failure they require emergency treatment.

16. Will hypertension cause any damage to my body?

Left unchecked, high blood pressure will over the years cause damage to the blood vessels of the heart and brain that leads to heart attacks and strokes. It also places extra strain on the heart, causing thickening of the heart muscle and heart failure and it damages the kidneys and can lead to kidney failure.

17. If I have diabetes do I have to be more careful to control my high blood pressure?

As diabetes itself increases the risk of cardiovascular complications, blood pressure (which can further increase risk) needs careful attention. In general most doctors will consider treating blood pressure in patients with diabetes at lower levels than in patients who do not have diabetes.

18. If I have high blood pressure, should I talk with my doctor if I am thinking about getting pregnant?

It is important to talk to your doctor if you have high blood pressure and are planning a pregnancy. This is because high blood pressure can create problems during pregnancy for both mother and baby.

Blood pressure can be treated during pregnancy, but only certain drugs can be used and your doctor knows which drugs are safe and which should be avoided.

19. Will blood pressure medication make me feel funny or sick?

These days drugs are safe and generally free of major side effects, but no drug is completely free of side effects in all patients.

As blood pressure drugs work by reducing blood pressure, sometimes too great a fall in blood pressure can cause dizziness on standing. This can be a problem in the summer months and especially when rising quickly from squatting. Dizziness on standing also can be worse in older patients.

There are a variety of other symptoms that can result from blood pressure medications and if these appear in the days or weeks after treatment has begun you should consult your doctor. However, do not stop medications yourself without medical advice, as sometimes the blood pressure will rebound to very high levels that can be dangerous.