What is hypertension?
Blood pressure is the force exerted by circulating blood against the walls of your arteries. Every heartbeat creates a wave of pressure — highest during the contraction phase (systole) and lowest during the relaxation phase (diastole). This is why blood pressure is expressed as two numbers: systolic over diastolic, measured in millimeters of mercury (mmHg).
Hypertension — commonly called high blood pressure — occurs when this force is persistently elevated above normal levels. The current threshold, established by the 2017 ACC/AHA guidelines, is 130/80 mmHg or above. At this level, arterial walls experience chronic mechanical stress that, over years and decades, causes structural damage.
Think of your arteries like garden hoses. Under normal pressure they are supple and resilient. Under chronically high pressure, they gradually stiffen, develop microtears that become sites of plaque deposition, and can develop aneurysms (dangerous bulges). The heart, meanwhile, must work harder with every beat — leading over time to hypertrophy (thickening) of the left ventricle and eventual heart failure.
What makes hypertension particularly dangerous is its silence. Most people feel completely normal with significantly elevated blood pressure — there is no pain, no warning signal. Organ damage accumulates invisibly for years or decades until a catastrophic event — heart attack, stroke, kidney failure — finally reveals what has been happening internally. This is why regular blood pressure monitoring is not optional; it is essential.
Blood pressure categories
| Category | Systolic (mmHg) | Diastolic (mmHg) | Action | |
|---|---|---|---|---|
| Normal | <120 | and | <80 | Maintain healthy habits |
| Elevated | 120–129 | and | <80 | Lifestyle changes; recheck in 3–6 months |
| Stage 1 Hypertension | 130–139 | or | 80–89 | Lifestyle ± medication depending on CV risk |
| Stage 2 Hypertension | ≥140 | or | ≥90 | Lifestyle + medication recommended |
| Hypertensive Crisis | ≥180 | and/or | ≥120 | Seek emergency care immediately |
In people over 60, it is common to have elevated systolic pressure (≥130 mmHg) with normal diastolic pressure (<80 mmHg). This is called isolated systolic hypertension and is caused by age-related arterial stiffening. It carries the same risks as combined hypertension and requires the same management — but treatment must be cautious to avoid excessive lowering of diastolic pressure, which can reduce coronary perfusion.
Primary vs. secondary hypertension
Primary (essential) hypertension — 90–95% of cases
The vast majority of hypertension has no single identifiable cause. It develops gradually over years from the interaction of genetic predisposition with environmental factors including excess dietary sodium, physical inactivity, obesity, alcohol, chronic stress, and ageing. There is no cure, but it is highly manageable with lifestyle changes and medication.
Secondary hypertension — 5–10% of cases
When hypertension has an identifiable underlying cause, it is called secondary. This is important to recognise because treating the underlying condition may normalise or significantly improve blood pressure. Secondary causes should be investigated in: younger patients (<30) with no obvious risk factors; patients with resistant hypertension (not controlled on 3+ medications); sudden onset of significant hypertension; or specific clinical clues.
| Secondary cause | Prevalence in hypertensives | Clinical clues | Diagnosis |
|---|---|---|---|
| Obstructive sleep apnea (OSA) | ~30% of resistant HTN | Snoring, daytime sleepiness, obesity, morning headaches | Overnight polysomnography or home sleep test |
| Primary aldosteronism | ~5–10% of hypertensives | Resistant HTN, low potassium, adrenal incidentaloma | Aldosterone-to-renin ratio; adrenal CT; adrenal vein sampling |
| Renovascular disease | ~1–5% | Resistant HTN in young woman; renal artery bruit; flash pulmonary edema | CT or MR angiography; Duplex ultrasound |
| Chronic kidney disease | Very common in CKD | Elevated creatinine, proteinuria, abnormal urine sediment | eGFR, urine albumin-to-creatinine ratio |
| Thyroid disease | Hypothyroid: diastolic HTN; Hyperthyroid: systolic HTN | Weight change, fatigue, palpitations, temperature intolerance | TSH, free T4 |
| Pheochromocytoma | Rare (<0.5%) | Episodic HTN, headache, sweating, palpitations ("the 5 Ps") | Plasma/urine metanephrines; adrenal imaging |
| Cushing's syndrome | Rare | Central obesity, striae, easy bruising, glucose intolerance | 24-hr urinary free cortisol; dexamethasone suppression test |
| Medications/substances | Common | NSAIDs, oral contraceptives, decongestants, stimulants, liquorice, cocaine | Medication review and discontinuation trial |
Symptoms and warning signs
This is the most important thing to understand about hypertension: it almost never causes symptoms until it reaches crisis levels or has already caused organ damage. There is no "headache of hypertension," no warning twinge, no signal that would prompt most people to seek help. Blood pressure must be measured — it cannot be felt.
Severe headache · Chest pain · Shortness of breath · Blurred or double vision · Nausea/vomiting · Confusion or altered consciousness · Nosebleed that won't stop · Weakness or numbness on one side · Difficulty speaking
What "symptoms" actually indicate
When patients report feeling their blood pressure is high based on symptoms like headache, flushing, or dizziness, studies consistently show poor correlation with actual measured blood pressure. These symptoms have many other causes and should not be used to self-diagnose or self-manage hypertension. The only reliable way to know your blood pressure is to measure it.
Symptoms that do reliably suggest hypertensive damage include:
- Vision changes: Blurring, loss of vision, or floaters — may indicate hypertensive retinopathy
- Ankle swelling and breathlessness: Signs of hypertension-induced heart failure
- Foamy urine or reduced urination: Signs of hypertensive nephropathy
- Sudden neurological symptoms: May signal hypertensive encephalopathy or stroke
Causes and risk factors
Non-modifiable factors
- Age: Blood pressure rises with age as arteries stiffen. More than 70% of adults over 65 have hypertension.
- Genetics / family history: Hypertension is 30–60% heritable. Having a first-degree relative with hypertension roughly doubles your risk.
- Race/ethnicity: African Americans develop hypertension earlier, more severely, and with higher rates of end-organ damage — a disparity driven by a combination of genetic, social, and healthcare access factors.
- Sex: Before age 55, men have higher rates; after menopause, women's rates equalise and eventually exceed men's.
Modifiable factors
🧂 Excess Sodium
- Average intake: 3,400 mg/day
- Target: <2,300 mg/day
- Ideal: <1,500 mg/day for HTN
- Reducing by 1,000 mg lowers BP ~5 mmHg
⚖️ Obesity
- Every 10 kg weight gain raises BP ~3 mmHg
- Abdominal fat especially harmful
- 5–10% weight loss produces meaningful BP reduction
- Linked to sleep apnea (secondary HTN)
🛋️ Physical Inactivity
- Regular aerobic exercise lowers BP 5–8 mmHg
- 150 min/week is target
- Even 30-min sessions have acute effect
- Isometric exercises (wall squat) show emerging benefit
🍺 Alcohol
- Heavy drinking raises BP significantly
- More than 2 drinks/day for men increases risk
- Alcohol also interferes with medications
- Reducing alcohol lowers BP 3–4 mmHg
😰 Chronic Stress
- Activates sympathetic nervous system
- Raises catecholamines chronically
- White-coat hypertension is real phenomenon
- Mindfulness and relaxation show modest benefit
🚬 Smoking
- Each cigarette causes acute BP spike
- Long-term effect on resting BP modest
- Dramatically multiplies cardiovascular risk
- Quitting essential for overall CV health
Diagnosis and measurement
How to measure blood pressure correctly
Inaccurate measurement is one of the most common problems in hypertension management. Office readings can be falsely elevated by anxiety, recent exertion, caffeine, or the "white coat effect." Here's how to get meaningful measurements:
- Sit quietly for 5 minutes before measuring — do not measure immediately after arriving
- Sit with back supported, feet flat on floor, arm at heart level — no crossing legs
- Use a validated upper-arm cuff — wrist monitors are less accurate
- No caffeine, exercise, or smoking for 30 minutes before measurement
- Take 2–3 readings 1 minute apart; use the average
- Check both arms at first — use the arm with higher reading going forward
- Record time, date, and reading — bring the log to appointments
Home blood pressure monitoring (HBPM)
The AHA strongly recommends home BP monitoring for all hypertensive patients. A week of twice-daily home readings provides far more diagnostic information than a single office visit. It also detects white-coat hypertension (normal at home, elevated in clinic) and masked hypertension (normal in clinic, elevated at home) — which require different management approaches.
Ambulatory blood pressure monitoring (ABPM)
ABPM involves wearing a BP cuff for 24 hours that takes automatic readings every 15–30 minutes. It is the gold standard for diagnosing hypertension and provides crucial information including: daytime vs. nighttime patterns, "dipping" status (blood pressure should dip 10–20% at night — non-dipping is a cardiovascular risk factor), and blood pressure variability.
Diagnostic workup
Once hypertension is confirmed, initial investigations aim to assess end-organ damage and identify secondary causes:
- Blood tests: electrolytes, creatinine, eGFR, fasting glucose, HbA1c, lipid panel, TSH, aldosterone-to-renin ratio (if secondary causes suspected)
- Urine: urinalysis, urine albumin-to-creatinine ratio (UACR)
- ECG: left ventricular hypertrophy, arrhythmia
- Echocardiogram: (selected patients) assess LV mass, function, diastolic dysfunction
- Fundoscopy: hypertensive retinopathy grading
Medications for hypertension
The decision to start medication depends on blood pressure level, overall cardiovascular risk, and response to lifestyle changes. Most guidelines recommend medication for all Stage 2 hypertension (≥140/90) and for Stage 1 patients with high cardiovascular risk (10-year ASCVD risk ≥10%, diabetes, chronic kidney disease, or established cardiovascular disease).
| Drug class | Examples | BP reduction | Best for | Key side effects |
|---|---|---|---|---|
| ACE inhibitors | Lisinopril, Ramipril, Perindopril | 10–15/6–8 mmHg | Diabetes, CKD with proteinuria, post-MI, heart failure | Dry cough (10–15%); avoid in pregnancy; rarely angioedema |
| ARBs (Sartans) | Losartan, Valsartan, Olmesartan | 10–15/6–8 mmHg | ACE inhibitor intolerance (cough); similar indications | No cough; angioedema rare; avoid in pregnancy |
| Calcium channel blockers (CCB) | Amlodipine, Lercanidipine (dihydropyridines); Diltiazem, Verapamil (non-DHP) | 10–15/6–8 mmHg | Isolated systolic HTN; elderly; angina; African American patients | Ankle oedema (DHPs); bradycardia/constipation (non-DHPs); grapefruit interaction |
| Thiazide/thiazide-like diuretics | Chlorthalidone (preferred), Indapamide, Hydrochlorothiazide | 8–12/4–6 mmHg | Volume-dependent HTN; elderly; African American patients; combination therapy | Low potassium; low sodium; elevated uric acid; glucose effects; erectile dysfunction |
Combination therapy: Most patients with Stage 2 hypertension require two or more medications to reach target. Starting with a single-pill combination (SPC) improves adherence significantly compared to separate tablets. A common first-line combination is ACE inhibitor/ARB + CCB or thiazide diuretic.
| Drug class | Examples | Use case | Notes |
|---|---|---|---|
| Beta-blockers | Bisoprolol, Metoprolol, Carvedilol | Heart failure, post-MI, arrhythmia, angina; not first-line for uncomplicated HTN | Avoid in asthma/COPD; can mask hypoglycemia; erectile dysfunction |
| Potassium-sparing diuretics | Spironolactone, Eplerenone | Resistant HTN; heart failure; primary aldosteronism; fourth-line add-on | Spironolactone causes gynaecomastia; monitor potassium with ACEi/ARB |
| Alpha-blockers | Doxazosin, Prazosin | Resistant HTN; benign prostatic hyperplasia | Orthostatic hypotension — titrate carefully; not first-line |
| Centrally acting agents | Clonidine, Methyldopa | Resistant HTN; methyldopa preferred in pregnancy | Rebound hypertension on abrupt discontinuation (clonidine) |
| Direct vasodilators | Hydralazine, Minoxidil | Resistant HTN; CKD patients; pregnancy (hydralazine) | Reflex tachycardia; minoxidil causes hirsutism; usually require diuretic combination |
Resistant hypertension is defined as blood pressure above target despite optimal doses of three antihypertensive medications from different classes — including a diuretic. True resistant HTN occurs in about 10–15% of treated hypertensives.
Before labelling a patient as "resistant," several factors must be excluded: poor medication adherence (the most common cause), white-coat effect (confirm with ABPM), secondary causes (especially OSA and primary aldosteronism), interfering medications (NSAIDs, decongestants, stimulants, oral contraceptives), and inadequate diuretic therapy.
When true resistance is confirmed, the most evidence-based next step is adding spironolactone (25–50 mg/day) — the PATHWAY-2 trial showed it was the most effective add-on agent. Novel approaches under investigation or in use include:
- Renal denervation: Catheter-based procedure that ablates sympathetic nerves around the renal artery. Phase 3 trials (SPYRAL HTN, RADIANCE II) show modest BP reductions of 8–10 mmHg systolic without medication changes. Approved in some countries; FDA approval pending.
- Baroreflex activation therapy (BAT): Implantable device that stimulates carotid baroreceptors to lower sympathetic tone. Approved in the U.S. for resistant hypertension.
Lifestyle changes: the evidence
Lifestyle modification can lower blood pressure as effectively as a single antihypertensive drug — and has benefits well beyond blood pressure. For Stage 1 hypertension in low-risk patients, guidelines support a trial of lifestyle-only therapy before starting medication.
| Intervention | Expected BP reduction | Evidence quality | Practical target |
|---|---|---|---|
| Sodium reduction | 5–6/2–3 mmHg | High | <2,300 mg/day; avoid processed foods, canned goods, restaurant meals |
| Weight loss | 5/4 mmHg per 5 kg lost | High | BMI target 18.5–24.9; even 5 kg loss produces meaningful effect |
| DASH diet | 11/5 mmHg | High | Emphasise fruits, vegetables, low-fat dairy, whole grains; limit saturated fat |
| Aerobic exercise | 5–8/3–4 mmHg | High | 150+ min/week moderate intensity; swimming and cycling particularly effective |
| Isometric exercise | 8/4 mmHg | Moderate-High | Wall squat 4 × 2-min holds, 3×/week — emerging strong evidence (2023 meta-analysis) |
| Alcohol reduction | 3–4/2 mmHg | High | ≤1 drink/day for women, ≤2 for men; ideally minimise |
| Potassium increase | 4–5/2–3 mmHg | Moderate | 3,500–5,000 mg/day from food (bananas, potatoes, spinach, beans) — check with doctor if on ACEi/ARB |
| Stress reduction (MBSR) | 3–4/2 mmHg | Moderate | Mindfulness-based stress reduction, yoga; device-guided slow breathing |
The DASH (Dietary Approaches to Stop Hypertension) diet is the most rigorously studied dietary intervention for hypertension. A full DASH diet combined with sodium restriction (1,500 mg/day) lowers systolic BP by 11 mmHg — equivalent to a single antihypertensive drug. The key principles: 4–5 servings daily of fruits and vegetables each, 2–3 servings low-fat dairy, whole grains as the main carbohydrate source, nuts and legumes 4–5 times/week, limited red meat, sweets, and sodium-rich foods.
Complications of uncontrolled hypertension
| Target organ | Complication | Mechanism | Prevention |
|---|---|---|---|
| Brain | Stroke (ischaemic and haemorrhagic), TIA, vascular dementia, hypertensive encephalopathy | Arterial damage, thrombosis, haemorrhage from weakened vessels | BP control reduces stroke risk 35–40% |
| Heart | Coronary artery disease, heart attack, left ventricular hypertrophy, heart failure (HFpEF) | Increased afterload, atherosclerosis acceleration, cardiac remodelling | Every 10 mmHg SBP reduction cuts CV events ~25% |
| Kidneys | Hypertensive nephropathy, chronic kidney disease, end-stage renal disease | Glomerular hyperperfusion, arteriosclerosis, ischaemic nephropathy | ACEi/ARBs specifically protect renal function |
| Eyes | Hypertensive retinopathy, retinal artery/vein occlusion, visual loss | Arteriolar narrowing, haemorrhage, exudates, papilloedema | BP control; annual fundoscopy in severe HTN |
| Arteries | Aortic aneurysm, aortic dissection, peripheral artery disease | Arteriosclerosis, medial degeneration, aortic wall stress | BP target <130/80; smoking cessation |
| Sexual function | Erectile dysfunction (men); sexual dysfunction (women) | Vascular damage to penile/pelvic blood flow | BP control; some medications (thiazides, beta-blockers) worsen ED — discuss alternatives |
Frequently asked questions
A reading of 180/120 mmHg or above constitutes a hypertensive crisis. If this occurs without symptoms (no chest pain, headache, vision changes, or neurological symptoms), it is called an urgency — contact your doctor immediately for urgent medication adjustment, but emergency department attendance may not be necessary. If 180/120+ occurs with any of these symptoms, this is a hypertensive emergency — call 911 immediately, as there may be acute end-organ damage occurring.
Primary hypertension cannot be cured but can be very effectively controlled. Some patients who achieve significant sustained weight loss and lifestyle transformation do reach normal blood pressure without medication — but this requires lifelong commitment to those habits. Secondary hypertension may be resolved if the underlying cause (e.g., primary aldosteronism treated surgically, sleep apnea treated with CPAP) is successfully addressed. Most patients need lifelong management — either lifestyle modification alone or combined with medication.
This is one of the most persistent myths in medicine. Mild to moderate hypertension — even significantly elevated readings — typically causes no headaches or symptoms whatsoever. Headaches are a symptom of hypertensive crisis (typically ≥180/120 mmHg). Multiple large studies have found no meaningful correlation between routine hypertension and ordinary headaches. If you frequently think you can "feel" your blood pressure rising, the only reliable approach is to actually measure it.
In 90–95% of cases (primary/essential hypertension), there is no single cause — it results from a combination of genetic predisposition, age-related arterial stiffening, excess sodium intake, physical inactivity, obesity, alcohol, and chronic stress. The remaining 5–10% (secondary hypertension) is caused by identifiable conditions: obstructive sleep apnea, primary aldosteronism, renovascular disease, chronic kidney disease, thyroid disorders, and rarely phaeochromocytoma or Cushing's syndrome. Certain medications also raise blood pressure significantly.
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- Williams B, et al. Spironolactone versus placebo, bisoprolol, and doxazosin to determine the optimal treatment for drug-resistant hypertension (PATHWAY-2). Lancet. 2015;386(10008):2059–2068.
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