High Blood Pressure (Hypertension): Causes, Symptoms, Diagnosis, Treatment, and Prevention

Article Summary

High blood pressure, also called hypertension, means blood pushes against artery walls at a higher pressure than is healthy over time. It usually causes no symptoms, so measuring blood pressure is the only reliable way to detect it. Untreated hypertension increases the risk of heart attack, stroke, heart failure, kidney disease, and other health problems. Diagnosis usually requires several accurate readings, often including measurements taken at home. Treatment may include reducing salt, exercising, managing weight, limiting alcohol, and taking medicines. Blood pressure targets and diagnostic thresholds vary slightly between guidelines, so results should be interpreted using local recommendations and individual health risks.

Cite as: High Blood Pressure (Hypertension): Causes, Symptoms, Diagnosis, Treatment, and Prevention. Brisbane (AU): Exon Publications; 2024 Apr 24 [updated 2026 Aug 19].

Introduction

High blood pressure, or hypertension, is one of the most common long-term health conditions. Blood pressure naturally rises and falls during the day, but when it stays too high, it can gradually damage blood vessels and organs. Because hypertension usually causes no warning symptoms, many people do not know they have it. Accurate measurement, early diagnosis, and effective treatment can greatly reduce the risk of cardiovascular disease and other complications (1, 2).

What Is High Blood Pressure?

Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps. A reading contains two numbers.

The systolic pressure, which is the first or upper number, measures pressure when the heart contracts and pumps blood. The diastolic pressure, the second or lower number, measures pressure when the heart relaxes between beats.

Blood pressure is measured in millimeters of mercury, written as mm Hg. A reading of 120/80 mm Hg, for example, means a systolic pressure of 120 and a diastolic pressure of 80.

Hypertension develops when blood pressure remains above the recommended range rather than rising only temporarily because of exercise, stress, pain, or another short-term cause (1, 2).

What Blood Pressure Is Considered High?

There is no single worldwide classification because major guidelines use somewhat different thresholds.

The 2025 American Heart Association and American College of Cardiology guideline defines normal blood pressure as below 120/80 mm Hg. A systolic pressure of 120–129 with a diastolic pressure below 80 is called elevated blood pressure. Hypertension begins at 130/80 mm Hg, with readings of 140/90 mm Hg or higher classified as stage 2 hypertension (1).

The 2024 European Society of Cardiology guideline uses a different system. It defines office hypertension as blood pressure of 140/90 mm Hg or higher. Readings below this level but above the optimal range are classified as elevated blood pressure (2).

These differences do not mean that one system is correct and the other is wrong. Blood pressure risk increases gradually rather than suddenly at one exact number. Treatment decisions therefore consider the actual reading together with age, cardiovascular risk, kidney disease, diabetes, previous heart disease or stroke, and other health factors (1, 2).

What Causes High Blood Pressure?

Most people with hypertension have primary hypertension, also called essential hypertension. This means there is no single disease causing the high blood pressure. Instead, it develops through a combination of age, genetics, lifestyle, kidney function, blood vessel changes, hormones, and environmental factors (1, 2).

Risk increases with age and is also associated with excess body weight, a diet high in sodium, low physical activity, heavy alcohol intake, smoking, poor sleep, and a family history of hypertension.

Some people have secondary hypertension, which means another medical condition or substance is causing the blood pressure to rise. Causes can include kidney disease, narrowing of arteries supplying the kidneys, primary aldosteronism, sleep apnea, thyroid disorders, and some adrenal gland disorders (1, 2).

Medicines and substances can also raise blood pressure. Examples include some anti-inflammatory medicines, decongestants, stimulants, corticosteroids, certain hormonal medicines, and some recreational drugs.

Finding a secondary cause can be particularly important when hypertension develops at an unusual age, becomes suddenly worse, or remains difficult to control despite several medicines.

What Are the Symptoms of High Blood Pressure?

High blood pressure usually causes no symptoms. A person can have hypertension for years while feeling completely well. This is why symptoms cannot be used to decide whether blood pressure is normal (1, 2).

Headaches, dizziness, or feeling unwell are sometimes blamed on hypertension, but these symptoms have many other causes and are not reliable signs of ordinary high blood pressure.

Very severe hypertension can sometimes cause acute damage to the brain, heart, kidneys, eyes, or major blood vessels. A blood pressure above 180/120 mm Hg together with symptoms such as chest pain, severe shortness of breath, confusion, new weakness or numbness, or major vision changes requires urgent assessment (1).

A very high reading without signs of acute organ damage is still important, but it is not automatically the same as a hypertensive emergency. The reading should be confirmed and managed promptly according to the clinical situation (1).

How Is High Blood Pressure Diagnosed?

Hypertension is usually diagnosed from repeated, correctly measured blood pressure readings rather than one isolated result. Blood pressure can change because of stress, activity, caffeine, pain, temperature, and many other factors (1-3).

An accurate office measurement requires an appropriately sized cuff and correct positioning. The person should usually be seated quietly with the back supported, feet on the floor, and arm supported at heart level. Several readings may be taken and averaged.

Measurements outside the clinic are increasingly important. Home blood pressure monitoring uses a validated blood pressure machine to record readings over several days. Ambulatory blood pressure monitoring uses a portable device that automatically measures blood pressure during normal daily activities and sleep. These methods can provide a more complete picture than a single clinic reading (3).

Some people have white-coat hypertension, where blood pressure is high in a medical setting but lower outside it. Others have masked hypertension, where clinic readings appear normal but blood pressure is high at home or during daily life. Home or ambulatory monitoring can help identify these patterns (1-3).

Validated upper-arm cuff devices are preferred. Current guidelines do not recommend relying on cuffless devices such as smartwatches to diagnose hypertension because their accuracy is not yet sufficiently established (1).

What Health Problems Can High Blood Pressure Cause?

Long-term hypertension damages blood vessels and makes the heart work harder. The higher the blood pressure and the longer it remains uncontrolled, the greater the risk of complications (1, 2).

High blood pressure is a major cause of stroke and contributes to both blocked and bleeding blood vessels in the brain. It also increases the risk of heart attack, coronary artery disease, and heart failure.

The kidneys contain many small blood vessels that can be damaged by high pressure. Hypertension can therefore cause or worsen chronic kidney disease. Kidney disease can also raise blood pressure, creating a cycle in which each condition makes the other worse.

High blood pressure can damage blood vessels in the eyes and is associated with disease of large arteries, including the aorta. Over many years, hypertension is also linked with a higher risk of cognitive decline and dementia (1, 2).

Lowering high blood pressure reduces the risk of major cardiovascular events across a wide range of adults (6).

How Can Lifestyle Changes Lower Blood Pressure?

Lifestyle changes are recommended for people with elevated blood pressure and hypertension, whether or not medicines are also needed (1, 2).

Reducing sodium can lower blood pressure. Much of the sodium people consume comes from processed, packaged, takeaway, and restaurant foods rather than salt added at the table.

Eating a healthy diet rich in vegetables, fruits, whole grains, legumes, nuts, and other minimally processed foods can help. Dietary patterns such as the DASH diet were specifically developed to support blood pressure control.

Regular physical activity lowers blood pressure and improves heart and blood vessel health. Both aerobic exercise, such as brisk walking, and appropriate strength exercise can be useful.

Weight management can reduce blood pressure in people with overweight or obesity. Even modest weight loss may help.

Limiting alcohol is important because regular heavy drinking can raise blood pressure and make hypertension more difficult to control.

Stopping smoking does not always produce a large lasting reduction in the blood pressure number itself, but it greatly reduces overall cardiovascular risk and is therefore particularly important for people with hypertension.

Adequate sleep and treatment of sleep apnea may also help some people. Lifestyle changes work best when they can be maintained over the long term rather than followed briefly as a restrictive program (1, 2).

What Medicines Are Used to Treat High Blood Pressure?

Many people need medicine in addition to lifestyle changes. The decision to start treatment depends on the blood pressure level, overall cardiovascular risk, other medical conditions, and the guideline being followed (1, 2, 4).

Common first-line medicines include angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), calcium channel blockers, and thiazide or thiazide-like diuretics. These medicines lower blood pressure in different ways.

Many people eventually need two or more medicines because hypertension is often controlled more effectively by combining drugs that act through different mechanisms. Current guidelines increasingly favor single tablets containing two medicines when combination treatment is required because this can simplify treatment and improve adherence (1, 4).

The best medicine depends on the person's age, kidney function, other diseases, possible side effects, pregnancy status, and medicines already being taken. Treatment should therefore be individualized rather than choosing a drug only from the blood pressure number.

Blood pressure medicines usually control hypertension rather than permanently cure it. Stopping treatment without medical guidance can allow blood pressure to rise again.

What Is Resistant High Blood Pressure?

Resistant hypertension means blood pressure remains above the treatment goal despite the use of at least three appropriate blood pressure medicines from different classes, usually including a diuretic, at the highest tolerated doses. It can also describe blood pressure that requires four or more medicines to remain controlled (5).

Before diagnosing resistant hypertension, doctors check whether the readings are accurate, whether medicines are being taken as prescribed, and whether white-coat hypertension is present. They may also look for medicines or substances that raise blood pressure and for secondary causes such as primary aldosteronism, kidney disease, or sleep apnea (5).

Treatment may involve improving the existing medicine combination, addressing an underlying cause, reducing excess sodium, and adding another medicine when appropriate.

What Blood Pressure Should Treatment Aim For?

The treatment goal depends on the guideline and the individual person. The 2025 US guideline recommends a treatment goal below 130/80 mm Hg for most adults with hypertension, while allowing treatment to be individualized in people whose health circumstances make this target inappropriate (1).

The 2024 European guideline generally recommends a treated systolic pressure of 120–129 mm Hg for many adults when this level is well tolerated, with less intensive targets when needed because of frailty, symptoms, very advanced age, or other circumstances (2).

Clinical trials and large meta-analyses show that lowering blood pressure reduces heart attacks, strokes, heart failure, and cardiovascular deaths, but treatment that is too intensive for a particular person can cause dizziness, fainting, electrolyte disturbances, or kidney problems (6). The goal is therefore effective control without causing unacceptable harm.

Can High Blood Pressure Be Prevented?

Not every case of hypertension can be prevented because age, genes, and some medical conditions cannot be changed. However, the chance of developing high blood pressure can often be reduced.

Maintaining a healthy weight, staying physically active, eating a diet low in excess sodium and rich in plant foods, limiting alcohol, avoiding smoking, and getting adequate sleep all support healthy blood pressure (1, 2).

Regular blood pressure measurement is also important because early hypertension usually causes no symptoms. Finding rising blood pressure before complications develop creates an opportunity to make lifestyle changes and begin treatment when needed.

Conclusion

High blood pressure is common, usually symptomless, and an important cause of heart disease, stroke, kidney disease, and other health problems. Diagnosis should be based on accurate, repeated measurements rather than a single reading. Home or ambulatory monitoring can help confirm the diagnosis and identify blood pressure patterns that may be missed in the clinic. Treatment combines sustainable lifestyle changes with medicines when needed. Although guidelines differ slightly in the numbers used to define and treat hypertension, they agree on the central message: controlling persistently high blood pressure substantially reduces the risk of serious cardiovascular complications.

References

1. Jones DW, Ferdinand KC, Taler SJ, et al. 2025 AHA/ACC/AANP/AAPA/ABC/ACCP/ACPM/AGS/AMA/ASPC/NMA/PCNA/SGIM Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. J Am Coll Cardiol. 2025;86(18):1567-1678. https://doi.org/10.1016/j.jacc.2025.05.007


2. McEvoy JW, McCarthy CP, Bruno RM, et al. 2024 ESC Guidelines for the management of elevated blood pressure and hypertension. Eur Heart J. 2024;45(38):3912-4018. https://doi.org/10.1093/eurheartj/ehae178


3. Liu J, Brettler J, Ramirez UA, et al. Home Blood Pressure Monitoring. Am J Hypertens. 2025;38(4):193-202. https://doi.org/10.1093/ajh/hpae151


4. Al-Makki A, DiPette D, Whelton PK, et al. Hypertension pharmacological treatment in adults: a World Health Organization guideline executive summary. Hypertension. 2022;79(1):293-301. https://doi.org/10.1161/HYPERTENSIONAHA.121.18192


5. Schiffrin EL, Fisher NDL. Diagnosis and management of resistant hypertension. BMJ. 2024;385:e079108. https://doi.org/10.1136/bmj-2023-079108


6. Blood Pressure Lowering Treatment Trialists' Collaboration. Pharmacological blood pressure lowering for primary and secondary prevention of cardiovascular disease across different levels of blood pressure: an individual participant-level data meta-analysis. Lancet. 2021;397(10285):1625-1636. https://doi.org/10.1016/S0140-6736(21)00590-0

This article is part of the 'Public Education Series' initiative by Exon Publications.

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