Hesperian Health Guides

What is High Blood Pressure?

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Measuring a person’s blood pressure tells how much force is needed for the heart to move blood through the body and back to the heart. It is normal for blood pressure to go up and down during the day depending on exercise, eating, feelings, etc. But having high blood pressure most of the time is not healthy. High blood pressure (also called hypertension) is a sign that the heart is working too hard.

When people have high blood pressure, lowering it helps them live longer. Medicines are sometimes needed to lower blood pressure but high blood pressure can often be lowered by eating healthier foods, using less salt, and exercising. Quitting tobacco and alcohol also helps. And treating a person’s diabetes will help their heart too. There are many ways to lower blood pressure.

Sometimes there is no clear reason why a person has high blood pressure. As people grow older, their blood pressure gradually gets higher as their arteries stiffen with age. For some women, pregnancy increases blood pressure. High blood pressure can also run in families, meaning that if you have parents or other close relatives with this problem, it might be a problem for you too.

When blood pressure is too high

Blood pressure measured regularly at over 140/90 is considered high blood pressure. But if a person has other health conditions, her acceptable blood pressure numbers may be higher or lower. For example, it is normal for blood pressure to go up a little as people get older, and this may not be a problem for a person with no other health problems. If blood pressure is regularly more than 130/80 or is getting higher over time, try different ways to lower it and continue checking blood pressure to see what works.

Usually, a person with high blood pressure will not notice any signs unless his blood pressure is very high. Unfortunately, no signs does not mean no harm. The only way to know if you have high blood pressure is to have it checked.

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High blood pressure and pregnancy

Health workers and midwives usually measure the blood pressure of pregnant women at every visit. It is common and healthy for a woman’s blood pressure to be a little lower than usual during the first 6 months of pregnancy. A healthy blood pressure stays between 90/60 and 140/90 and does not rise much during pregnancy. High blood pressure during pregnancy causes less blood to circulate. This brings less food to the developing baby, so the baby might grow too slowly.

Blood pressure measuring between 140 and 150 for the top number or between 90 and 100 for the bottom number may be treated without medicines by having the woman rest more and lie on her left side. Signs of more serious health problems include shortness of breath, chest pains, or higher blood pressure. High blood pressure in pregnancy can be a sign of pre-eclampsia, an emergency that can lead to premature birth, bleeding, convulsions, and even death.

When is blood pressure too low?

Blood pressure lower than 90 (systolic) over 60 (diastolic) is generally considered to be low blood pressure. Some people have no problems from low blood pressure. But if there is dizziness or fainting, low blood pressure may need treatment. Low blood pressure can be a sign of dehydration or other problems. It is important to find the cause of low blood pressure to treat it.

When blood pressure drops very quickly and there are other signs such as confusion, cold sweat, or a weak, fast pulse, this could be an emergency condition called shock. Once signs of shock begin, it usually gets worse very fast until the body shuts down completely. Treat shock quickly to save the person’s life (see Shock, in the chapter on First Aid).

It is important to check your blood pressure

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Anyone with a blood pressure measurement device can check blood pressure. Usually health workers check your blood pressure at every visit, but you may be able to check it at a pharmacy or a health promotion event in your community or workplace. Keep a record of your blood pressure to see if it changes over time.

If you get a blood pressure device, you can learn to check your own blood pressure at home. Blood pressure equipment can be shared safely among people.

High blood pressure is a warning that heart disease might be developing or has already begun. Over time, the increased pressure damages the organs in your body and can lead to heart attacks, heart failure, strokes, kidney disease, and eye damage. When you learn to check your own blood pressure, you can see how exercise and healthy eating help your blood pressure improve.

This page was updated:13 Jan 2021