Doctors usually define normal blood pressure as a reading that is less than 140/90 mmHg. This is normally referred to as 140 over 90, where the first number (e.g. 140) refers to systolic blood pressure, the blood pressure in the arteries when the heart is beating, and the second number (e.g. 90) refers to diastolic blood pressure, the blood pressure in the arteries when the heart is at rest between heartbeats.
Blood pressure that is higher than 140/90 mmHg is called hypertension (the medical term for high blood pressure). Hypertension that isn’t treated can greatly increase a person’s risk of developing coronary heart disease, heart failure, kidney failure and stroke, so it is important that it is managed and treated.
Before suggesting any treatment your doctor will probably carry out some tests to discover whether or not your high blood pressure has an underlying cause. These may include an electrocardiogram, or ECG, to check the health of your heart, a full blood count, kidney function tests, electrolytes (sodium, potassium and other blood salts) and an analysis of your urine. If there appears to be no underlying medical condition causing your high blood pressure, you have what doctors refer to as essential hypertension. Essential hypertension accounts for 90 to 95 per cent of cases of high blood pressure. Although essential hypertension can’t usually be cured, it can be treated to prevent complications. Your doctor may also ask you to have a cholesterol test in case you need medication or lifestyle changes to lower your lipid levels.
Your doctor will also review any current medicines you are taking. Some medicines can contribute to hypertension, including non-steroidal anti-inflammatory drugs (NSAIDs), oral contraceptives, corticosteroids and some medicines used for depression.
Your doctor will also want to check if you have any other risk factors, such as diabetes, smoking, high cholesterol, angina, or a family history of angina or heart attack, so that your absolute risk of cardiovascular disease can be determined.
For some people, making some simple lifestyle changes may be all that’s needed to bring blood pressure down. You may not need medicines, particularly if your doctor considers you’re at a low risk of developing complications. The following steps can reduce high blood pressure and also prevent many people from developing it in the first place.
Losing even a small amount of weight helps many people reduce their blood pressure without the need for medication. Increase your intake of fruits and vegetables, and choose foods that are low in saturated fat and high in fibre, vitamins and minerals. Your doctor or dietitian will be able to help you if you don’t know where to start.
Many canned, packaged and processed foods contain excessive amounts of salt (sodium chloride) so you should read the labels carefully and choose ‘low salt’ or ‘salt free’ wherever possible. Remove salt from your recipes wherever you can and limit smoked, cured or processed meat and meat products.
Limiting your drinking to a moderate amount of alcohol will help to keep your blood pressure normal. The National Heart Foundation of Australia recommends that men with high blood pressure should limit their intake to 2 units of alcohol or less per day, and women should limit their intake to 1 unit or less per day. A unit of alcohol is roughly equivalent to a standard glass of normal strength beer, a small glass of wine, or a single measure of spirit such as whisky or gin. Both men and women should have at least two alcohol-free days each week.
Taking part in a regular exercise programme will make you feel better and reduce your risk of developing serious or chronic illnesses. Aerobic activities that condition your heart and lungs, such as swimming, walking or cycling, are best. Start slowly and build up to doing at least 30 minutes of moderate exercise most days. If you don’t have time to do 30 minutes, do what you can: you can do 3 sessions of 10 minutes if this is more convenient. If you are taking medication, have a history of serious illness or have not exercised for a while, check with your doctor before starting a programme. Weight lifting causes increases in blood pressure and isn't recommended.
You should also make every attempt to give up smoking. Your doctor will be able to suggest the best quitting strategy for you to follow.
Depending on your level of risk for cardiovascular disease, your doctor may suggest that you take medicines to lower your blood pressure if your blood pressure remains high after a period of the above lifestyle adjustments. The decision to treat high blood pressure is not based on your blood pressure alone, but also on your overall level of cardiovascular risk. One person may have a blood pressure of 145/90 mmHg and still be at sufficiently low risk that medicines are not needed, whereas another person with a blood pressure of 130/80 mmHg may need treatment.
There are certain circumstances in which doctors normally suggest you should start taking medicines immediately. These include the following:
If your doctor assesses your overall cardiovascular risk to be relatively low, it is likely they will recommend lifestyle modification and monitoring as the initial management.
There are several main types of antihypertensive medicines. The one you are prescribed will depend on any other medical conditions you may have, your risk of cardiovascular disease, other medicines you may be taking and the medicine’s potential for side effects. Response to medicines varies among individuals and your doctor may need to try different types and dosages before finding the best one for you. Blood pressure can sometimes be adequately controlled by one medicine, but often a combination of 2 or 3 medicines is required.
Here are some of the types of medicines currently available.
These medicines lower blood pressure by blocking the production of a hormone (angiotensin II) that narrows blood vessels, allowing the blood vessels to widen and blood to flow more easily, thus lowering blood pressure. The ACE inhibitors are also used in heart failure and are useful for preserving kidney function in people with diabetes and kidney disease.
Examples of ACE inhibitors are: captopril (e.g. Acenorm, Capoten), enalapril (e.g. Alphapril, Amprace, Auspril, Renitec), fosinopril (e.g. Fosipril, Monace, Monopril), lisinopril (e.g. Fibsol, Lisodur, Prinivil, Zestril), perindopril (e.g. Coversyl, Perindo), quinapril (e.g. Accupril, Acquin, Filpril), ramapril (e.g. Prilace, Ramace, Tritace, Tyrzan) and trandolapril (e.g. Dolapril, Gopten, Odrik, Tranalpha).
There are few side effects with these medicines, but the most common is a harmless but persistent dry cough. ACE inhibitors are not suitable for pregnant women as they may damage the growing baby.
The angiotensin II blockers are newer than the ACE inhibitors, but work in a similar way. However, they are more selective in their action and may cause fewer side effects, for example they are less likely than the ACE inhibitors to cause cough.
Examples include candesartan (Atacand), eprosartan (Teveten), irbesartan (Avapro, Karvea), losartan (Cozaar), olmesartan (Olmetec), telmisartan (Micardis) and valsartan (Diovan).
Like the ACE inhibitors, these medicines should not be taken by pregnant women as they pose a risk to the developing baby. They are also used in heart failure and for preservation of kidney function.
These medicines work by blocking the flow of calcium in the muscles of the heart and blood vessels, causing the blood vessels to relax and open up. This lowers the blood pressure. They are often useful for older people and people with asthma or angina or peripheral vascular disease. They include amlodipine (e.g. Norvasc, Perivasc), felodipine (Felodil XR, Felodur ER, Plendil ER), lercanidipine (Zanidip), nifedipine (e.g. Adalat Oros, Addos XR, Adefin XL), diltiazem (e.g. Cardizem CD, Vasocardol CD) and verapamil (e.g. Anpec SR, Cordilox SR, Isoptin SR, Veracaps SR). Many of these medicines are controlled-release preparations, releasing the medicine slowly into the body during the day.
Side effects vary among calcium channel blockers but can include flushing, swelling of the ankles, gastrointestinal upset (particularly with verapamil) and palpitations; however, generally these medicines are effective and well tolerated.
Diuretics work by helping the kidneys to pass accumulated salt and water. This decreases the amount of fluid in the body and so lowers blood pressure. Diuretics also cause blood vessels to dilate (expand), which lessens the pressure on them.
There are 2 types of diuretics used frequently in the treatment of high blood pressure. Thiazide diuretics, for example indapamide (e.g. Dapa-Tabs, Insig, Natrilix SR) and hydrochlorothiazide (Dithiazide), are frequently used but can cause excess potassium to be excreted in the urine, which can be a problem for people with impaired kidney function.
Potassium-sparing diuretics, such as amiloride (Kaluril), help the body retain potassium. Various combination products are marketed which combine thiazides with potassium-sparing diuretics, for example hydrochlorothiazide plus amiloride (Moduretic). Likewise, thiazide diuretics are often co-prescribed with ACE inhibitors (another type of high blood pressure medicine that tends to cause retention of potassium).
Side effects of diuretics can include dizziness, weakness, excessive urination, and more rarely rash and gastrointestinal symptoms. People who have diabetes, liver disease or gout need to be closely monitored by their doctor while taking diuretics as the medicines may aggravate these conditions.
The National Heart Foundation recommends that thiazide diuretics should be used as a first-line treatment for high blood pressure only in people aged 65 years or over. Diuretics are usually prescribed in low doses only, so if you find your diuretic is not reducing your blood pressure, higher doses are unlikely to improve things and your doctor will probably try another type of medicine.
These medicines reduce the number of nerve impulses that occur in the heart and blood vessels.
Alpha-blockers, for example prazosin (e.g. Minipress, Pressin), relax muscles in the walls of the blood vessels and reduce the resistance to blood flow thus allowing blood to flow more easily. They are not usually recommended in the first instance for blood pressure control.
Beta-blockers, such as atenolol (e.g. Noten, Tenormin, Tensig), metoprolol (e.g. Betaloc, Lopresor, Metrol, Minax, Toprol-XL), pindolol (e.g. Barbloc, Visken) and propranolol (e.g. Deralin, Inderal), work by blocking the action of adrenaline and noradrenaline in the heart. Adrenaline speeds up the heart and makes it pump harder, thus increasing blood pressure. Beta-blockers slow the heartbeat, and reduce the force of its contractions so less blood is pumped through the vessels, thus lowering blood pressure. The National Heart Foundation recommends that beta-blockers should not be used as a first-line treatment for people with uncomplicated high blood pressure (people with uncomplicated high blood pressure usually have no symptoms).
Beta-blockers are also used for angina, fast heartbeat and prevention of migraine. They are not suitable for people with asthma or certain heart conditions, and because they act on the nervous system they may cause lowered mood or lethargy in some people. They may sometimes cause narrowing of the airways, such as in asthma, and cold hands and feet. Unlike many other high blood pressure medicines, some beta-blockers are safe for use in pregnancy.
Some beta-blockers, such as labetalol (e.g. Presolol, Trandate) and carvedilol (e.g. Dilasig, Dilatrend, Kredex) block both beta and alpha receptors.
Like adrenergic blockers, methyldopa (Hydopa), clonidine (Catapres) and moxonidine (Physiotens) act on the nervous system, but more widely than either alpha- or beta-blockers. They act on the part of the brain that controls blood pressure, which results in expansion of the blood vessels, thus lowering blood pressure. Although very effective, they have more side effects than other antihypertensive medicines, including fatigue, dry mouth, depression, impotence and headache, so they are generally considered second- or third-line treatment. Methyldopa is still occasionally used to treat pregnant women who can’t take other blood pressure medicines because of the effect on the developing baby.
These include hydralazine (Alphapress) and minoxidil (Loniten). They have a strong blood pressure lowering effect and are a second- or third-line treatment, used for high blood pressure that doesn’t respond to other medications or in emergency situations. They are used generally under specialist supervision. Sodium nitroprusside and diazoxide are given by injection or intravenous infusion in emergencies when blood pressure needs to be reduced rapidly.
Less than half of people with mild to moderate hypertension have it controlled satisfactorily with one medicine (monotherapy). A combination of the medicines described above is often required for adequate control. There appears to be no greater incidence of side effects with combinations than with using either drug on its own.
The medicines may be prescribed individually to be taken as a combination regimen, or sometimes there may be a combination product available that combines different classes of antihypertensives. Your doctor will choose the most appropriate one for you based on your individual medical circumstances.
Some people may wonder why they need to take medicines for a condition that doesn’t have symptoms and doesn’t appear to affect their quality of life. Your doctor is aware of this and will try to avoid treatments that make you feel bad or interfere with your lifestyle. Although taking medication may seem like a chore, it is being prescribed to prevent serious illness or even death. Always take medicines according to instructions, and do not stop taking them abruptly as this can cause problems. If you have any questions about your medicine, always ask your doctor.
Last Reviewed: 26 October 2009