What Is High Blood Pressure (Hypertension)?

Blood pressure measures the force that blood exerts against the walls of your arteries as the heart pumps it through the body. It is expressed as two numbers: systolic (the pressure when the heart beats and pumps blood) over diastolic (the pressure when the heart rests between beats). Hypertension — commonly called high blood pressure — is defined by the American Heart Association (AHA) as a consistent blood pressure reading of 130/80 mmHg or above.

This threshold was lowered from the previous standard of 140/90 mmHg in the landmark 2017 AHA/ACC guidelines, based on mounting evidence that cardiovascular risk rises significantly above 130/80. Under these guidelines, approximately 46% of US adults now have hypertension — up from 32% under older criteria — making it the single most common modifiable cardiovascular risk factor.

Why It Matters: High blood pressure is the leading risk factor for heart attack, stroke, heart failure, and kidney disease worldwide. It is directly responsible for approximately 500,000 deaths per year in the United States alone.
116MUS adults have hypertension
46%of US adults affected
1 in 5don't know they have it
500Kannual US deaths linked to HBP

Symptoms — Why Hypertension Is Called the Silent Killer

High blood pressure is often called the "silent killer" because it typically causes no symptoms for years or even decades. Most people with hypertension feel completely normal — which is precisely why it is so dangerous and why regular blood pressure monitoring is essential for everyone over 18.

When symptoms do occur, they are often at very high levels (hypertensive crisis, above 180/120 mmHg) and may include:

  • Severe headaches, particularly at the back of the head upon waking
  • Nosebleeds (epistaxis) that are difficult to stop
  • Shortness of breath or chest tightness
  • Dizziness or lightheadedness
  • Visual disturbances — blurred vision or seeing spots
  • Facial flushing
  • Blood in urine
  • Pounding sensation in the chest, neck, or ears
Hypertensive Crisis (>180/120 mmHg): If your reading exceeds 180/120 and you have symptoms such as chest pain, shortness of breath, severe headache, back pain, numbness, weakness, or vision changes — call 911 immediately. This is a medical emergency.

Causes and Risk Factors

Approximately 90–95% of hypertension cases are classified as primary (essential) hypertension — meaning no single identifiable cause exists. It develops gradually over years from a combination of genetic predisposition and lifestyle factors. The remaining 5–10% is secondary hypertension, caused by an identifiable underlying condition.

Primary Hypertension Risk Factors

  • Age: Blood pressure tends to rise with age as arterial walls stiffen. Over 65% of adults over 60 have hypertension.
  • Family history: Having a parent or sibling with hypertension significantly increases your risk — suggesting strong genetic components.
  • Obesity and overweight: Excess body weight requires the heart to pump more blood to supply oxygen to tissues, increasing pressure on artery walls. Even a 5 kg weight loss can reduce systolic BP by 4–5 mmHg.
  • High sodium intake: Sodium causes water retention, increasing blood volume and therefore pressure. The average American consumes 3,400 mg/day — more than double the AHA's recommended maximum of 1,500 mg/day for people with hypertension.
  • Physical inactivity: Sedentary individuals have 30–50% higher hypertension risk than active individuals.
  • Excessive alcohol consumption: More than 1 drink/day (women) or 2 drinks/day (men) is associated with elevated BP.
  • Chronic stress: Persistent stress activates the sympathetic nervous system, chronically elevating blood pressure.
  • Race and ethnicity: Black Americans develop hypertension more frequently, at younger ages, and with greater severity than White Americans — likely due to a combination of genetic susceptibility, environmental factors, and social determinants of health.

Secondary Hypertension Causes

  • Chronic kidney disease (most common secondary cause)
  • Primary aldosteronism (adrenal gland overproducing aldosterone)
  • Obstructive sleep apnea
  • Thyroid disorders (both hypo- and hyperthyroidism)
  • Medications: NSAIDs, oral contraceptives, decongestants, stimulants
  • Renal artery stenosis
  • Coarctation of the aorta (narrowing of the main artery)

Blood Pressure Categories (AHA 2017)

Normal: Systolic <120 AND Diastolic <80 mmHg
Elevated: Systolic 120–129 AND Diastolic <80 mmHg
Stage 1 HTN: Systolic 130–139 OR Diastolic 80–89 mmHg
Stage 2 HTN: Systolic ≥140 OR Diastolic ≥90 mmHg
Hypertensive Crisis: Systolic >180 AND/OR Diastolic >120 mmHg

Blood pressure should always be measured at rest after sitting quietly for 5 minutes. Take 2–3 readings 1 minute apart and use the average. The AHA recommends home monitoring with a validated upper-arm cuff device as a complement to office measurements, particularly to identify white-coat hypertension (elevated only in clinical settings) or masked hypertension (normal in clinic but elevated at home).

Evidence-Based Lifestyle Treatments

Lifestyle modification is the first-line treatment for elevated blood pressure and Stage 1 hypertension, and an essential complement to medication for all stages. The most effective interventions:

  • DASH Diet: The Dietary Approaches to Stop Hypertension diet has the strongest evidence of any dietary intervention, reducing systolic BP by 8–14 mmHg. It emphasizes fruits, vegetables, whole grains, low-fat dairy, and lean proteins while limiting sodium, saturated fat, and added sugars.
  • Sodium reduction: Reducing sodium from 3,400 to 1,500 mg/day reduces systolic BP by 5–6 mmHg. Read labels carefully — bread, canned soups, deli meats, cheese, and restaurant food are the leading sodium sources in the US diet.
  • Aerobic exercise: 150 minutes of moderate-intensity aerobic exercise per week (brisk walking, cycling, swimming) reduces systolic BP by 4–9 mmHg. Even 30 minutes of daily walking produces clinically significant reductions.
  • Weight reduction: Losing 10 kg (22 lbs) reduces systolic BP by approximately 5–20 mmHg. Even 5% body weight reduction produces meaningful improvement.
  • Limit alcohol: Reducing to moderate intake (≤1 drink/day women, ≤2 drinks/day men) reduces systolic BP by 2–4 mmHg.
  • Quit smoking: Each cigarette produces a temporary BP spike. Quitting smoking is the single most impactful action for overall cardiovascular risk reduction.
  • Stress management: Mindfulness-based stress reduction (MBSR), slow breathing exercises (6 breaths per minute), and yoga have each demonstrated 3–5 mmHg systolic reductions in clinical trials.
  • Potassium intake: Adequate potassium (4,700 mg/day) counteracts sodium. Banana (422mg), sweet potato (542mg), white potato (926mg), and spinach (839mg) are excellent sources.

Medications for Hypertension

When lifestyle modifications are insufficient — or for Stage 2 hypertension — antihypertensive medications are required. The four primary classes used as first-line therapy:

  • ACE Inhibitors (e.g., lisinopril, ramipril): Block the production of angiotensin II, causing vasodilation. Also protective for kidneys in diabetes and heart failure. Side effect: dry cough (10–15% of patients).
  • ARBs (e.g., losartan, valsartan): Block angiotensin II receptors. Similar efficacy to ACE inhibitors without the cough. Preferred alternative.
  • Calcium Channel Blockers (e.g., amlodipine, diltiazem): Prevent calcium from entering heart and blood vessel muscle cells, reducing contraction force and BP. Particularly effective in older adults and Black patients.
  • Thiazide Diuretics (e.g., hydrochlorothiazide, chlorthalidone): Reduce blood volume by increasing sodium and water excretion. Among the most cost-effective antihypertensives. Chlorthalidone is preferred over HCTZ based on cardiovascular outcome data.

Complications of Untreated Hypertension

Sustained hypertension silently damages the cardiovascular system over years. Major complications include stroke (hypertension accounts for 54% of all strokes worldwide), heart attack (each 20/10 mmHg above normal doubles cardiovascular risk), heart failure, chronic kidney disease and kidney failure, vision loss from hypertensive retinopathy, peripheral artery disease, vascular dementia, and aortic aneurysm.

"Treating hypertension is among the most cost-effective interventions in all of preventive medicine — yet half of those with hypertension remain uncontrolled."