High blood pressure

Also known as hypertension

High blood pressure (hypertension) is a common condition in which the force of your blood against your artery walls is too high, too often. Ongoing high blood pressure puts stress on the heart and can lead to health problems, such as heart disease and stroke.

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Key points

  1. One in five New Zealanders has high blood pressure, but most don't know they do.
  2. It is more common in older age groups but it can affect younger people too. 
  3. High blood pressure usually doesn't have symptoms; therefore, it is important to get your blood pressure measured regularly. Your doctor, nurse or pharmacist can do this for you.
  4. Untreated high blood pressure can cause serious problems such as stroke, heart failure, heart attack and kidney failure.
  5. You can control high blood pressure through healthy lifestyle habits and medications if needed.
  6. If you need medication, take it every day as prescribed and ask questions of your doctor or pharmacist if you don't understand anything.

What is high blood pressure?

Your blood pressure is measured in millimetres of mercury (which is written as mmHg) and is recorded as systolic blood pressure over diastolic blood pressure, for example, 120/70 mmHg.

  • As a general guide, an ideal blood pressure is between 90/60 mmHg and 120/80 mmHg.
  • High blood pressure is considered to be 140/90 mmHg or higher.
  • A blood pressure reading between 120/80mmHg and 140/90mmHg could mean you're at risk of developing high blood pressure,  if you don't take steps to keep your blood pressure under control.
  • Low blood pressure is considered to be 90/60mmHg or lower.

Why is high blood pressure a problem?

Ongoing high blood pressure damages the blood vessels, especially if you also have raised blood cholesterol or diabetes, or if you smoke.

If blood vessels become narrowed or blocked, a heart attack or stroke may occur. High blood pressure is also linked to kidney and eye damage and poor circulation in the arteries of the legs.

How does high blood pressure cause damage?

  • If you imagine a garden hose with the nozzle at a narrow setting, water will leave the hose with great force and could damage tender plants. The body behaves in a similar way when there is increased pressure (ie. high blood pressure) in the arteries.
  • If the arteries were delivering blood at high pressure to delicate organs such as the eyes, kidneys and brain they can cause damage, possibly permanent.
  • If the heart has to beat against increased artery pressure, eventually, after a period of years, it will feel the strain and tire.
  • Normal blood pressure delivers an effective blood supply to all parts of the body without damaging sensitive organs.

What causes high blood pressure?

Essential hypertension

In most people with high blood pressure, there is no obvious cause. This is called essential hypertension. Risk factors for essential hypertension are:

The more risk factors you have, the higher your risk of developing high blood pressure.

Secondary causes

About 10% of high blood pressure cases are due to an underlying problem or condition and are known as secondary causes.

This includes causes such as:

  • kidney disease
  • narrowing of the arteries supplying the kidneys (renal artery stenosis)
  • Cushing's syndrome
  • some medications such as the oral contraceptive pill and nonsteroidal anti-inflammatory drugs (ibuprofen, naprosyn, diclofenac etc)
  • other conditions such as diabetes and lupus
  • recreational drugs, such as cocaine, amphetamines and crystal methamphetamine
  • some herbal remedies or supplements.

Who needs to get their blood pressure checked?

All adults should have their blood pressure checked regularly. Most people with high blood pressure do not get any symptoms so you need to get it checked to know if you have it. You can have your blood pressure checked by your doctor, nurse or pharmacist.

How often will depend on your age, whether you are taking any medications and your general health. Regular checks are especially important for:

  • all men aged over 45 and women over 55 years
  • anyone who has previously had high blood pressure, a stroke, a heart attack, raised blood cholesteroldiabetes or high blood pressure during pregnancy
  • smokers
  • those who are overweight
  • pregnant women and those taking the oral contraceptive pill
  • those with a family history of heart disease.

If you have low blood pressure, you may feel light-headed, faint or dizzy on standing up.

How is high blood pressure diagnosed?

To diagnose high blood pressure, you need to have your blood pressure checked by your doctor, nurse or pharmacist. They will often take several readings over weeks or months to see what the trend is.

Sometimes your doctor, nurse or pharmacist will suggest 24-hour blood pressure monitoring. This involves wearing a blood pressure unit for up to 24 hours to collect a series of blood pressure and heart rate readings at different times of the day and night. 

24-hour blood pressure monitoring Heart Foundation

How is high blood pressure treated?

For mild high blood pressure, adopting the self-care steps listed below such as stopping smoking, eating a balanced diet, less salt, less alcohol and becoming more physically active may be all that is needed.

For moderate to severe high blood pressure, you are likely to need medication as well as working hard at these self-care measures.

Self-care for high blood pressure

  • Stop smoking – quitting is the most important step to reduce your risk of heart attack and stroke.
  • Achieve and maintain a healthy bodyweight. The more overweight you are, the more strain you are putting on your heart and cardiovascular system. For some people, losing 5-10kg of excess weight is all that is needed to get their blood pressure back to normal. Check with your doctor, nurse or pharmacist as to what is right for you.
  • Eat a balanced diet – low in saturated fat with whole grains, eight servings of coloured vegetables and fruit, and two to three servings of low-fat milk or milk products a day. Learn more about the DASH eating plan to lower high blood pressure.
  • Eat less salt. Use herbs, spices, fruit and vinegar for flavouring and dressings and choose low-salt versions of packaged foods, avoid pickled food and avoid salty or fatty takeaway foods.
  • Watch alcohol consumption. Aim to have no more than one to two alcoholic drinks a day.
  • Avoid liquorice – it contains a chemical that can raise blood pressure.
  • Be active every day. Find ways to put a little bit more activity in your day at every opportunity. Take the stairs at work. Park 5 minutes further away. Aim to get 30 to 60 minutes of moderate activity most days of the week. Walking, cycling and swimming are ideal. Find an activity you enjoy so you can keep it up. 
  • Get your blood pressure checked. Every adult should have their blood pressure checked regularly. Your doctor, nurse or pharmacist will advise you how often – it will depend on your age, whether you are taking any medications and your general health. 

Medications for high blood pressure

Medications can help control high blood pressure and reduce the damage from high blood pressure, but they do not cure it. Usually, medication will need to be taken for life, unless losing weight and the lifestyle changes are so successful that your blood pressure returns to normal levels without medication.

There a variety of medicines that can be used to lower blood pressure each of these groups of medicines works differently. Often two or three medications are needed and it may take time to find the right combination and dosage. It is important to let your doctor or pharmacist know about any side effects you may have and to follow instructions carefully.

Examples of medicines to treat blood pressure:

  • ACE inhibitors such as cilazapril, lisinopril, quinapril.
  • ARBs such as candesartan, irbesartan, losartan.
  • Beta blockers such as bisoprolol, metoprolol, propranolol.
  • Calcium channel blockers such as amlodipine, diltiazem, felodipine.
  • Diuretics (also called water pills) such as bendroflumethiazide, chlortalidone, indapamide.

Read more about medicines to treat blood pressure.

Because high blood pressure puts you at increased risk of cardiovascular disease, you may also be prescribed other medicines to help reduce your risk of heart disease and stroke, such as:

Learn more

Dash eating plan to lower high blood pressure
High blood pressure personal stories Health Talk online
High Blood Pressure  Heart Foundation NZ
High Blood Pressure NHS Choices
Family health history Learn Genetics (Genetic Science Learning Centre), University of Utah, USA, 2015

Credits: used with permission from Heart Foundation. Latest update Oct 2015. Images from123rf.com. Reviewed By: Health Navigator