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

High blood pressure (hypertension) affects around 14 million people in the UK, yet an estimated 5 million people have the condition without knowing it. It is one of the biggest risk factors for heart attack, stroke, and kidney disease in the UK, and is the leading cause of preventable death worldwide. The good news is that hypertension is highly manageable with the right treatment and lifestyle changes.

Understanding Blood Pressure: What the Numbers Mean

Blood pressure is measured in millimetres of mercury (mmHg) and recorded as two numbers:

  • Systolic pressure (the top number) — the pressure in your arteries when your heart beats
  • Diastolic pressure (the bottom number) — the pressure between heartbeats

NHS and NICE blood pressure categories:

  • Optimal: Below 120/80 mmHg
  • Normal: 120–129/80–84 mmHg
  • High normal: 130–139/85–89 mmHg
  • Stage 1 hypertension: 140–159/90–99 mmHg (or 135/85 on home monitoring)
  • Stage 2 hypertension: 160–179/100–109 mmHg (or 150/95 on home monitoring)
  • Severe hypertension: 180/110 mmHg or above — urgent medical review needed

High Blood Pressure: UK Statistics

  • 14 million people in the UK have been diagnosed with hypertension
  • A further 5.5 million remain undiagnosed
  • Hypertension accounts for 12% of all GP visits in the UK
  • It is the second biggest risk factor for premature death and disability in England (after smoking)
  • Treating hypertension prevents an estimated 30,000 heart attacks and 40,000 strokes in the UK each year
  • Only about half of people diagnosed with hypertension have it adequately controlled

Symptoms of High Blood Pressure

High blood pressure is often called the “silent killer” because it typically causes no symptoms until it reaches dangerous levels or causes a complication. Most people only discover they have it through routine checks at their GP surgery or pharmacy.

In rare cases of severely elevated blood pressure (hypertensive crisis — usually above 180/120 mmHg), symptoms may include:

  • Severe headaches
  • Blurred or double vision
  • Nosebleeds
  • Shortness of breath
  • Chest pain
  • Confusion

If you experience these symptoms, call 999 or go to your nearest A&E immediately.

Causes and Risk Factors

Primary (Essential) Hypertension — 90–95% of Cases

No single identifiable cause. Risk factors include:

  • Age — blood pressure naturally rises with age; over 65% of people aged 60+ have hypertension
  • Family history
  • Excess weight and obesity
  • Physical inactivity
  • High salt intake — UK adults consume on average 8.4g salt/day; NICE recommends under 6g
  • Excessive alcohol
  • Smoking
  • Chronic stress
  • Ethnicity — people of Black African and Caribbean descent have higher rates of hypertension and more severe forms
  • Type 2 diabetes — see our type 2 diabetes guide
  • Chronic kidney disease

Secondary Hypertension — 5–10% of Cases

Caused by an underlying condition, such as:

  • Kidney disease (most common secondary cause)
  • Obstructive sleep apnoea — see our sleep apnoea guide
  • Primary aldosteronism (overactive adrenal glands)
  • Thyroid disease
  • Certain medications — NSAIDs, oral contraceptives, decongestants, steroids

Diagnosis: How the NHS Tests for High Blood Pressure

Following NICE guideline NG136, the NHS uses a staged approach to diagnosing hypertension:

1. Clinic Blood Pressure Measurement

If your reading is 140/90 mmHg or above in the GP surgery, NICE recommends confirming the diagnosis with ambulatory blood pressure monitoring (ABPM) or home blood pressure monitoring (HBPM) to rule out “white coat hypertension” (anxiety-driven elevation in clinical settings).

2. Ambulatory Blood Pressure Monitoring (ABPM)

A portable device worn for 24 hours takes automatic readings every 30 minutes during the day. This is the gold standard for diagnosing hypertension — at least 14 daytime readings are needed. Hypertension is confirmed if the daytime average is 135/85 mmHg or above.

3. Home Blood Pressure Monitoring (HBPM)

If ABPM is not tolerated, home monitoring over 7 days (morning and evening, 2 readings each time, discarding day 1) is an acceptable alternative. Average of ≥135/85 confirms hypertension.

4. Further Investigations

Once diagnosed, your GP will arrange blood tests (kidney function, blood sugar, cholesterol), urine test (protein in urine), and possibly an ECG to assess cardiovascular risk and screen for secondary causes.

NHS Treatment for High Blood Pressure

NICE guideline NG136 forms the basis of NHS hypertension management. The stepped-care approach depends on your age and ethnicity:

Step 1: Lifestyle Changes (for All Patients)

  • Reduce salt — cutting salt from 9–10g to 5–6g/day can lower BP by 2–8 mmHg; avoid processed foods, ready meals, and adding salt at the table
  • DASH diet — rich in fruits, vegetables, whole grains, low-fat dairy, and lean proteins; reduces BP by 8–14 mmHg
  • Regular exercise — 150 minutes of moderate activity per week; reduces BP by 4–9 mmHg
  • Weight loss — losing 1kg reduces BP by approximately 1 mmHg
  • Limit alcohol — no more than 14 units/week; avoid binge drinking
  • Stop smoking — smoking raises blood pressure and dramatically increases cardiovascular risk
  • Reduce stress — mindfulness, sleep hygiene, relaxation techniques

Step 2: First-Line Medication (NICE NG136 2019)

Choice depends on age and ethnicity:

  • Under 55 (non-Black ethnicity): ACE inhibitor (ramipril, lisinopril) or angiotensin receptor blocker (losartan, candesartan)
  • 55 or over, or Black African/Caribbean at any age: Calcium channel blocker (amlodipine, felodipine)

Step 3: Add a Second Drug

If Step 2 doesn’t achieve target blood pressure, combine an ACE inhibitor/ARB with a calcium channel blocker.

Step 4: Add a Third Drug

Add a thiazide-like diuretic (chlortalidone or indapamide). NICE moved away from bendroflumethiazide in the 2019 update.

Step 5: Resistant Hypertension

If blood pressure remains above 140/90 on three drugs, consider: low-dose spironolactone (if potassium ≤4.5 mmol/L), higher-dose thiazide, alpha-blocker (doxazosin), or beta-blocker. Consider referral to a hypertension specialist.

Blood Pressure Targets

  • Under 80 years: Below 140/90 mmHg in clinic (below 135/85 at home)
  • 80 years and over: Below 150/90 mmHg in clinic
  • Diabetes: Below 140/80 mmHg (or 130/80 if high cardiovascular risk)
  • Chronic kidney disease with proteinuria: Below 130/80 mmHg

Complications of Untreated High Blood Pressure

Untreated hypertension silently damages organs over years and decades:

  • Heart attack — hypertension is the leading cause; see our heart attack guide
  • Stroke — hypertension causes over 50% of strokes; see our stroke guide
  • Heart failure
  • Atrial fibrillation (AF) — see our atrial fibrillation guide
  • Chronic kidney disease — see our CKD guide
  • Peripheral arterial disease
  • Aortic aneurysm
  • Hypertensive retinopathy — damage to blood vessels in the retina
  • Vascular dementia

Monitoring Your Blood Pressure at Home

Home blood pressure monitoring is recommended by NICE and is highly effective for managing hypertension long-term. The British and Irish Hypertension Society (BIHS) maintains a validated device list at bihsoc.org. Key tips:

  • Use a validated upper-arm monitor (not wrist monitors for most people)
  • Measure seated, after 5 minutes of rest, feet flat on floor
  • Take two readings morning and evening for 7 days
  • Record results to share with your GP
  • Avoid caffeine, alcohol, or exercise in the 30 minutes before measuring

UK Support and Resources

  • Blood Pressure UK — bloodpressureuk.org | Charity dedicated to lowering the nation’s blood pressure
  • British Heart Foundation — bhf.org.uk | Heart helpline: 0300 330 3311
  • British and Irish Hypertension Society (BIHS) — bihsoc.org | Validated BP monitor list and clinical guidelines
  • NHS Health Check — free check for adults aged 40–74 including blood pressure screening
  • NICE NG136 — full hypertension management guideline available at nice.org.uk

What Major Health Sites Often Miss About Hypertension

1. Ethnicity-Specific Treatment Differences

The 2019 NICE NG136 update made ethnicity a primary factor in drug selection — recommending calcium channel blockers rather than ACE inhibitors as first-line treatment for Black African and Caribbean patients of any age. This is because ACE inhibitors are significantly less effective in this population. This UK-specific NICE distinction is rarely highlighted on US health websites, yet is critical for appropriate UK prescribing.

2. ABPM as Diagnostic Gold Standard

The UK is one of the few countries that mandates ambulatory blood pressure monitoring (ABPM) to confirm a hypertension diagnosis before treatment (per NICE NG136). Most US guidelines still rely primarily on clinic readings. This means UK patients are less likely to be over-diagnosed with “white coat hypertension” — but also means some may face delays if ABPM devices aren’t readily available at their surgery.

3. Updated Thiazide Recommendations

NICE updated its 2019 guidelines to recommend chlortalidone or indapamide over bendroflumethiazide, based on better cardiovascular outcome evidence. Many UK patients are still on bendroflumethiazide prescribed before this update — if you are, it’s worth discussing with your GP whether switching is appropriate.

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