What is High Blood Pressure?
High blood pressure, or hypertension, means the force of blood against artery walls stays elevated over time. Under the 2017 ACC/AHA thresholds, stage 1 hypertension starts at 130-139 systolic or 80-89 diastolic mm Hg, and stage 2 at 140/90 mm Hg or above. It rarely causes symptoms, which is why measurement — not how you feel — is the only way to know.
Key takeaways
- Normal is below 120/80 mm Hg; elevated is 120-129 systolic with diastolic under 80; stage 1 is 130-139 or 80-89; stage 2 is 140/90 or higher.
- Hypertension is usually symptomless, so it is found by measurement rather than by feeling unwell.
- It is the single largest modifiable risk factor for stroke and a major driver of heart, kidney, and eye disease.
- Home and ambulatory readings are now central to diagnosis, not just office measurements.
- Sodium reduction, potassium-rich eating, activity, alcohol moderation, and weight change all lower blood pressure measurably.
Overview
Blood pressure is written as two numbers: systolic, the peak pressure when the heart contracts, and diastolic, the resting pressure between beats. Both matter. When pressure stays elevated for years, arteries stiffen and thicken, the left ventricle of the heart works harder and enlarges, and the delicate vessels of the kidneys, retina, and brain are gradually damaged. None of this announces itself. The overwhelming majority of people with hypertension feel completely normal, and the myth that headaches or nosebleeds reliably signal high pressure causes real harm by delaying diagnosis.
The upside is that few conditions respond as predictably to treatment. Lowering systolic pressure by even 10 mm Hg produces measurable reductions in stroke and heart events across large trials. Most people reach target with a combination of everyday changes and one or two well-chosen medicines, and modern practice increasingly relies on home readings to confirm both the diagnosis and the response to treatment.
What High Blood Pressure is
Blood pressure depends on how much blood the heart pumps and how much resistance the arteries offer. In most adults with hypertension — called primary or essential hypertension — resistance rises slowly over decades through a mix of arterial stiffening, kidney handling of sodium, hormonal signalling through the renin-angiotensin system, and nervous system tone. There is no single defect to point at.
A minority have secondary hypertension caused by something identifiable: kidney disease, obstructive sleep apnea, primary aldosteronism, thyroid disorders, narrowing of a kidney artery, or medicines including decongestants, NSAIDs, and some contraceptives. Secondary causes are worth looking for when pressure is very high, hard to control, or appears suddenly at a young age.
Common symptoms
Hypertension is often called a silent condition because it usually produces no symptoms until pressure is extremely high or organ damage has occurred.
- No symptoms — by far the most common situation
- Headache — only reliably associated with very high pressure
- Dizziness or lightheadedness — sometimes reported, often from other causes
- Nosebleeds — occasionally linked to severe elevations, not routine hypertension
- Shortness of breath on exertion — may reflect strain on the heart
- Blurred or changing vision — from effects on retinal vessels
Less common symptoms
- Chest discomfort — needs urgent evaluation rather than being attributed to blood pressure
- Facial flushing — commonly attributed to blood pressure but usually unrelated
- Blood in the urine — a possible sign of kidney involvement
- Pounding sensation in the chest, neck, or ears
Risk factors
- Age — arteries stiffen over time, so prevalence rises steadily after 40
- Excess weight, particularly abdominal — increases blood volume and vascular resistance
- High sodium and low potassium intake — shifts how the kidneys handle fluid
- Physical inactivity — regular activity lowers resting pressure independently of weight
- Excess alcohol — a dose-related rise in blood pressure that reverses when intake falls
- Family history and African ancestry — both associated with earlier onset and higher average pressures
- Chronic kidney disease — the relationship runs in both directions
- Obstructive sleep apnea — a common and treatable contributor to resistant hypertension
- Chronic stress and poor sleep — associated with higher average readings
Causes
For most people no single cause is identifiable. Instead, inherited tendencies interact with decades of dietary sodium, body weight, alcohol, activity levels, and age-related arterial stiffening. The kidneys sit at the centre of the process: their handling of sodium and water sets the long-run baseline, which is why kidney disease and hypertension so often travel together.
Secondary causes deserve a deliberate look in specific situations — pressure that is severe, resistant to three medicines, or newly appearing before age 30 or after 65. Common culprits include sleep apnea, primary aldosteronism, renal artery narrowing, thyroid disease, and medicines such as NSAIDs, decongestants, stimulants, and some hormonal contraceptives.
How it is diagnosed
Diagnosis requires more than one high reading, and out-of-office measurement is now standard for confirming it.
| Test or assessment | What it looks at |
|---|---|
| Office blood pressure measurement | Taken after five minutes seated with back supported, feet flat, arm at heart level, and a correctly sized cuff. Two readings on two or more separate visits are typically used. |
| Home blood pressure monitoring | A validated upper-arm cuff used twice in the morning and twice in the evening for about a week. Home averages predict outcomes better than single office readings. |
| 24-hour ambulatory monitoring | A cuff worn for a full day and night. It identifies white-coat hypertension, masked hypertension, and loss of the normal overnight dip. |
| Basic laboratory panel | Kidney function and electrolytes, urine albumin-to-creatinine ratio, fasting glucose or A1C, lipid panel, and thyroid function to look for contributors and organ effects. |
| Electrocardiogram | Looks for signs of left ventricular thickening or previous silent injury; an echocardiogram is added when structural change is suspected. |
| Targeted secondary-cause testing | Aldosterone-to-renin ratio, sleep study, or kidney artery imaging when the pattern suggests an identifiable underlying cause. |
Treatment overview
Treatment combines everyday changes with medication when needed, and targets are individualized — commonly below 130/80 mm Hg for many adults, with adjustments for age, frailty, and other conditions. The categories below are what clinicians select among; specific agents and dosing are set by a prescriber.
Dietary pattern change
The DASH pattern — vegetables, fruit, whole grains, legumes, nuts, low-fat dairy, limited red meat and sweets — lowers systolic pressure by several mm Hg on its own, more when combined with sodium reduction.
Sodium reduction and potassium increase
Cutting sodium toward roughly 1,500-2,300 mg a day and increasing potassium from food produce reliable reductions, though potassium targets need care in kidney disease.
Physical activity and weight management
Regular aerobic activity, isometric exercise such as wall sits or handgrip work, and modest weight loss each lower pressure measurably.
Alcohol reduction and smoking cessation
Reducing alcohol lowers pressure in a dose-related way; stopping smoking does not lower baseline pressure much but sharply reduces overall cardiovascular risk.
First-line medication classes
Thiazide-type diuretics, ACE inhibitors, angiotensin receptor blockers, and calcium channel blockers. Choice depends on age, ancestry, kidney function, and other conditions.
Add-on medication classes
Mineralocorticoid receptor antagonists, beta blockers, alpha blockers, and centrally acting agents are added for resistant pressure or specific indications.
Treating contributors
Managing sleep apnea, reviewing medicines that raise pressure, and addressing chronic kidney disease often unlock control that medication alone does not.
Lifestyle considerations
- Measure at home with a validated upper-arm cuff and bring the log or app record to appointments.
- Cook more meals from scratch — roughly 70% of dietary sodium comes from packaged and restaurant food, not the salt shaker.
- Build the plate around vegetables, fruit, beans, and whole grains for potassium, fibre, and magnesium.
- Aim for 150 minutes a week of moderate aerobic activity; adding two or three short isometric sessions has good supporting evidence.
- Keep alcohol modest, or lower — the blood pressure effect is dose-related and reverses.
- Protect 7-9 hours of sleep, and have loud snoring or witnessed pauses in breathing assessed.
- Check labels on decongestants and NSAIDs, which can raise pressure and blunt some medicines.
- Take medicines consistently; missed doses are one of the most common reasons pressure appears resistant.
Prevention
- Keep blood pressure below 120/80 mm Hg where possible; prevention and treatment use the same levers.
- Maintain a healthy weight — the relationship between weight and pressure is strong and continuous.
- Limit sodium and choose potassium-rich whole foods from early adulthood onward.
- Stay physically active most days rather than concentrating exercise into one session.
- Keep alcohol within moderate limits and avoid tobacco entirely.
- Have blood pressure checked at least every 2 years if normal, and yearly or more often if elevated.
Warning signs and when to get help
Signs that need emergency care
If you believe you are experiencing a medical emergency, call emergency services immediately (911 in the United States).
- Blood pressure at or above 180/120 mm Hg with chest pain, shortness of breath, back pain, numbness or weakness, difficulty speaking, or vision change — call emergency services immediately
- Sudden face droop, arm weakness, or speech difficulty — remember BE-FAST and call emergency services
- Chest pressure, tightness, or pain spreading to the arm, jaw, neck, or back, with or without sweating and nausea
- Sudden severe headache unlike any before, or a seizure
- Sudden severe tearing chest or back pain — a possible aortic emergency
Signs that warrant a prompt appointment
These are not emergencies, but they are worth a call to your clinician rather than a wait-and-see.
- Readings repeatedly at or above 180/120 mm Hg without symptoms — contact your clinician the same day
- Home readings consistently above your agreed target
- New ankle swelling, persistent cough, or dizziness after a medication change
- Fainting or near-fainting on standing
- New shortness of breath with everyday activity
Questions to ask a healthcare professional
Take these to your next appointment — or build an agenda with the Appointment Prep tool.
- What blood pressure target is right for me given my age and other conditions?
- Is my home monitor a validated model, and can you check my technique?
- How many readings do you want, and over what period?
- Which of my current medicines or supplements could be raising my pressure?
- Should I be tested for sleep apnea or other secondary causes?
- What side effects should I expect from this medicine, and what should prompt a call?
- How much sodium should I aim for each day?
- When should we recheck my kidney function and electrolytes?
Frequently asked questions
What is a normal blood pressure reading?
Under the 2017 ACC/AHA categories, normal is below 120/80 mm Hg. Elevated is 120-129 systolic with diastolic below 80. Stage 1 hypertension is 130-139 systolic or 80-89 diastolic, and stage 2 is 140/90 mm Hg or higher. Track yours with the Blood Pressure Tracker.
Can high blood pressure be cured?
Primary hypertension is generally managed rather than cured. Some people control it with lifestyle change alone, especially early and with significant weight loss, but it usually returns if those changes stop. Secondary hypertension can sometimes resolve when the underlying cause is treated.
Why is my reading higher at the doctor than at home?
That pattern is called white-coat hypertension and is common. It is one reason home or 24-hour ambulatory readings are now used to confirm the diagnosis. The reverse — normal in clinic, high at home — is called masked hypertension and carries real risk.
Do I need to take blood pressure medicine forever?
Not necessarily, but often for a long time. Some people reduce or stop medicines after substantial weight loss, sodium reduction, or treatment of sleep apnea. Never stop or change a blood pressure medicine on your own — rebound rises can be dangerous.
Does drinking more water lower blood pressure?
Adequate hydration supports normal circulation, but drinking extra water is not a treatment for hypertension. Sodium reduction, potassium-rich eating, activity, weight, and alcohol have far larger effects. The Water Intake Calculator covers general hydration.
Which arm should I use to measure blood pressure?
Check both arms once; if readings differ consistently, use the arm with the higher value from then on. Sit quietly for five minutes first, keep feet flat and back supported, and rest the arm at heart level.
Sources
- American Heart Association — High Blood Pressure — Category thresholds and measurement technique
- CDC — High Blood Pressure — US prevalence and public health guidance
- NHLBI — DASH Eating Plan — Dietary pattern with trial evidence for lowering pressure
- MedlinePlus — High Blood Pressure — Consumer overview and related tests
- USPSTF — Hypertension in Adults: Screening — Screening with confirmation outside the clinical setting
Health Captain links to primary public-health and clinical sources so you can read the original material yourself. See our sources policy.