Hypertension, commonly known as high blood pressure, is a chronic medical condition in which the blood pressure in the arteries is persistently elevated. According to the World Health Organization, hypertension affects an estimated 1.28 billion adults aged 30–79 worldwide, yet nearly half of those affected are unaware of their condition. It is often called the "silent killer" because it typically produces no symptoms until significant organ damage has occurred. Understanding this condition is the first step toward managing it effectively and reducing the risk of life-threatening complications.

Blood pressure is the force exerted by circulating blood against the walls of the arteries. It is expressed as two numbers: systolic pressure (the pressure when the heart contracts) over diastolic pressure (the pressure when the heart relaxes between beats). A normal reading is generally below 120/80 mmHg. Blood pressure is measured using a sphygmomanometer — either a manual device with a stethoscope or an automated oscillometric device. For accurate diagnosis, multiple readings should be taken on at least two separate occasions. Ambulatory blood pressure monitoring (ABPM) over 24 hours is considered the gold standard for confirming a diagnosis and ruling out white-coat hypertension.

Current guidelines from the European Society of Cardiology (ESC) and the American College of Cardiology (ACC) classify blood pressure into several stages. Normal blood pressure is below 120/80 mmHg. Elevated (or high-normal) is 120–129/<80 mmHg. Stage 1 hypertension is defined as 130–139/80–89 mmHg (ACC) or 140–159/90–99 mmHg (ESC). Stage 2 hypertension is 140+/90+ mmHg (ACC) or 160–179/100–109 mmHg (ESC). Stage 3 (severe) hypertension in the ESC classification is ≥180/≥110 mmHg. A hypertensive crisis occurs when blood pressure exceeds 180/120 mmHg and may require emergency treatment, especially if there is evidence of acute organ damage (hypertensive emergency).

Primary (essential) hypertension, which accounts for 90–95% of cases, has no single identifiable cause but results from a complex interplay of genetic, environmental, and lifestyle factors. Key risk factors include: age (risk increases significantly after 50), family history, obesity (BMI ≥30), high sodium intake (>5 g/day of salt), physical inactivity, excessive alcohol consumption, chronic stress, and smoking. Secondary hypertension (5–10% of cases) has identifiable causes such as renal artery stenosis, primary aldosteronism, pheochromocytoma, Cushing syndrome, thyroid disorders, or obstructive sleep apnea. Certain medications can also raise blood pressure, including NSAIDs, oral contraceptives, corticosteroids, and decongestants.

Lifestyle changes are the cornerstone of hypertension management and should be recommended to all patients regardless of blood pressure stage. The DASH diet (Dietary Approaches to Stop Hypertension) emphasizes fruits, vegetables, whole grains, and low-fat dairy while limiting saturated fats, red meat, and sweets — it can reduce systolic BP by 8–14 mmHg. Sodium restriction to less than 2,300 mg/day (ideally <1,500 mg/day) can lower systolic BP by 5–6 mmHg. Regular aerobic exercise — at least 150 minutes per week of moderate-intensity activity such as brisk walking — can reduce BP by 5–8 mmHg. Weight loss of even 5–10% of body weight produces clinically meaningful BP reductions. Limiting alcohol to no more than 1 drink/day for women and 2 for men, and smoking cessation are also critical. Stress management techniques including meditation, deep breathing, and cognitive behavioral therapy may provide additional benefit.

When lifestyle modifications are insufficient or when blood pressure is significantly elevated, pharmacotherapy is indicated. The five major first-line drug classes are: ACE inhibitors (e.g., ramipril, enalapril, lisinopril) — block the conversion of angiotensin I to angiotensin II, reducing vasoconstriction; common side effect is dry cough. ARBs (angiotensin II receptor blockers, e.g., losartan, valsartan, telmisartan) — block the AT1 receptor; similar efficacy to ACE inhibitors but without the cough. Calcium channel blockers (CCBs) (e.g., amlodipine, nifedipine, diltiazem) — relax vascular smooth muscle; particularly effective in elderly patients and those of African descent. Thiazide/thiazide-like diuretics (e.g., hydrochlorothiazide, indapamide, chlorthalidone) — reduce blood volume by promoting sodium excretion; monitor electrolytes regularly. Beta-blockers (e.g., bisoprolol, metoprolol, nebivolol) — reduce heart rate and cardiac output; now considered first-line mainly when there is a compelling indication such as heart failure, post-MI, or atrial fibrillation.

Current guidelines recommend initiating treatment with a single-pill combination (SPC) of two drugs at low doses for most patients with Stage 1 hypertension and above. A common starting combination is an ACE inhibitor or ARB with a CCB or diuretic. If blood pressure remains uncontrolled, the regimen is stepped up to a triple combination (ACE inhibitor/ARB + CCB + diuretic). If blood pressure is still not at target with three drugs at optimal doses, the patient is considered to have resistant hypertension, and spironolactone (a mineralocorticoid receptor antagonist) is recommended as the fourth agent. Other add-on options include alpha-blockers (doxazosin), centrally acting agents (moxonidine), or direct vasodilators. Treatment targets are generally <140/90 mmHg, with <130/80 mmHg for most patients who tolerate it, particularly those with diabetes or high cardiovascular risk.

Regular monitoring is essential for effective blood pressure management. Patients should be seen every 4 weeks after initiating or changing therapy until blood pressure is at target, then every 3–6 months for stable patients. Home blood pressure monitoring (HBPM) is strongly encouraged — patients should measure BP twice in the morning and twice in the evening for 7 consecutive days before each visit, discarding the first day's readings and averaging the rest. Target for home readings is <135/85 mmHg. Laboratory monitoring should include serum creatinine, eGFR, electrolytes (especially potassium), fasting glucose, lipid panel, and urinalysis for proteinuria at least annually. Patients on ACE inhibitors or ARBs require renal function checks 1–2 weeks after initiation or dose changes.

Persistent uncontrolled hypertension damages blood vessels throughout the body, leading to serious complications. Stroke — hypertension is the single most important risk factor for both ischemic and hemorrhagic stroke, increasing risk 3–4 fold. Myocardial infarction and heart failure — the left ventricle hypertrophies under chronic pressure overload, eventually leading to diastolic then systolic dysfunction. Chronic kidney disease — hypertension is the second leading cause of end-stage renal disease after diabetes; it damages the glomerular capillaries and accelerates nephron loss. Retinopathy — hypertensive retinopathy can progress from mild arteriolar narrowing to papilledema and vision loss. Aortic aneurysm and peripheral arterial disease are also significant consequences. Effective blood pressure control reduces stroke risk by 35–40%, MI risk by 20–25%, and heart failure risk by up to 50%.

Hypertensive disorders of pregnancy affect 5–10% of all pregnancies and are a leading cause of maternal and fetal morbidity. Chronic hypertension predates pregnancy. Gestational hypertension develops after 20 weeks without proteinuria. Preeclampsia involves hypertension with proteinuria or organ dysfunction and can progress to life-threatening eclampsia (seizures) or HELLP syndrome. Preferred antihypertensive agents in pregnancy include labetalol, nifedipine (extended-release), and methyldopa. ACE inhibitors, ARBs, and direct renin inhibitors are absolutely contraindicated in pregnancy due to teratogenic effects. Low-dose aspirin (75–150 mg daily) is recommended for prevention of preeclampsia in high-risk women from 12 weeks' gestation.

Key medications used in hypertension management include ramipril, enalapril, lisinopril, losartan, valsartan, telmisartan, amlodipine, nifedipine, hydrochlorothiazide, indapamide, bisoprolol, metoprolol, and spironolactone. For more information, explore related conditions on PillsCard: heart failure, chronic kidney disease, type 2 diabetes, and stroke prevention.