High Blood Pressure (Hypertension): Symptoms, Diagnosis & NHS Treatment

High blood pressure (hypertension) is one of the most common long-term conditions in the UK, affecting around 1 in 3 adults — yet nearly half of those with hypertension don’t know they have it. Often called the “silent killer,” hypertension rarely causes symptoms but is a leading risk factor for heart attack, stroke, kidney disease, and heart failure. This guide explains NHS blood pressure targets, the NICE treatment guidelines, and how to manage hypertension effectively.

Understanding Blood Pressure

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

• Systolic pressure (the upper number) — the pressure when the heart beats and pumps blood out
• Diastolic pressure (the lower number) — the pressure when the heart rests between beats

NICE defines blood pressure categories as:

• Normal: below 120/80 mmHg
• High-normal (elevated): 120-129/less than 80 mmHg
• Stage 1 hypertension: clinic BP 140-159/90-99 mmHg confirmed by ABPM or HBPM averaging 135/85 mmHg or above
• Stage 2 hypertension: clinic BP 160-179/100-109 mmHg (or ABPM/HBPM 150/95 mmHg or above)
• Stage 3 / severe hypertension: clinic systolic BP 180 mmHg or above, or diastolic 120 mmHg or above

Causes and Risk Factors

Primary (essential) hypertension (over 90% of cases) has no single identifiable cause — it results from a combination of genetic predisposition and environmental factors:

• Age — blood pressure rises progressively with age due to arterial stiffening
• Obesity — strongly associated; excess adipose tissue increases vascular resistance
• High salt (sodium) intake — promotes fluid retention and raises BP
• Sedentary lifestyle
• Alcohol excess — more than 14 units per week raises BP
• Smoking — causes acute BP elevation and accelerates arterial damage
• Family history
• Ethnicity — people of Black African or Caribbean heritage have higher hypertension prevalence and greater salt sensitivity
• Stress

Secondary hypertension (5-10%) has an identifiable cause and may be curable:

• Chronic kidney disease or renal artery stenosis
• Primary aldosteronism (Conn’s syndrome) — the most common secondary cause; suspect with resistant hypertension and low potassium
• Phaeochromocytoma — adrenal tumour producing adrenaline; suspect with episodic hypertension, headache, sweating, palpitations
• Cushing’s syndrome; sleep apnoea; medications (NSAIDs, combined oral contraceptive pill, steroids, some cold remedies)

Why High Blood Pressure Is Dangerous

Sustained hypertension damages blood vessel walls throughout the body, accelerating atherosclerosis and increasing pressure on the heart and organs. This leads to:

• Stroke — both ischaemic and haemorrhagic; hypertension is the biggest modifiable stroke risk factor
• Heart attack and coronary artery disease
• Heart failure — the left ventricle hypertrophies against increased afterload, eventually failing
• Chronic kidney disease — hypertension causes nephrosclerosis; CKD and hypertension form a vicious cycle
• Peripheral arterial disease
• Hypertensive retinopathy — vision changes; in severe hypertension, papilloedema and visual loss
• Aortic aneurysm and dissection
• Vascular dementia

NHS Diagnosis: ABPM and HBPM

NICE NG136 recommends confirming hypertension diagnosed in clinic with either:

• Ambulatory blood pressure monitoring (ABPM) — a device worn for 24 hours that records BP at 20-30 minute intervals throughout the day and night. The gold standard; eliminates white coat hypertension; NICE preferred method for diagnosis
• Home blood pressure monitoring (HBPM) — if ABPM is not suitable; patient records BP twice daily (morning and evening) for at least 4 days (ideally 7); average calculated from day 2 onwards

NICE recommends ABPM or HBPM because clinic measurements are often inflated by white coat effect (anxiety-related elevation during clinic appointments). Conversely, “masked hypertension” (normal clinic, high ambulatory) is also clinically important.

Blood tests at diagnosis include: U&E and creatinine (renal function), fasting glucose and HbA1c, fasting lipids, eGFR; urine albumin-to-creatinine ratio (ACR) for target organ damage; ECG (left ventricular hypertrophy).

NHS Treatment: Lifestyle Modifications

NICE recommends lifestyle changes for all people with hypertension, alongside medication for Stage 1 or above:

• Salt restriction — reduce to below 6g per day (1 teaspoon); avoid adding salt to food; reduce processed and ready-made foods. Each 6g reduction in daily salt reduces systolic BP by about 7-8 mmHg
• Weight loss — losing 10kg reduces systolic BP by about 10-20 mmHg
• DASH diet — the Dietary Approaches to Stop Hypertension diet (rich in fruit, vegetables, whole grains, low-fat dairy; low in saturated fat, red meat, and sodium) can reduce systolic BP by 8-14 mmHg
• Regular aerobic exercise — 30 minutes of moderate intensity (brisk walking, cycling, swimming) most days; reduces BP by 4-9 mmHg
• Limit alcohol — below 14 units per week; avoid binge drinking
• Stop smoking — does not directly lower resting BP but dramatically reduces overall cardiovascular risk
• Reduce caffeine — if consuming more than 4 cups of coffee daily

NHS Drug Treatment

NICE NG136 recommends a stepwise approach to antihypertensive therapy:

Step 1

• Under 55 years or with diabetes: Start an ACE inhibitor (e.g., ramipril, lisinopril) or angiotensin receptor blocker (ARB) (e.g., losartan, candesartan) if ACE inhibitor not tolerated
• 55 years and over, or Black African/Caribbean descent (any age): Start a calcium channel blocker (CCB) (e.g., amlodipine). Black African/Caribbean patients respond less well to ACE inhibitors and ARBs due to lower renin levels; CCBs are preferred

Step 2

If not at target on Step 1: add a second agent — either the ACE inhibitor/ARB + CCB combination. The “A+C” combination (ACE inhibitor/ARB + calcium channel blocker) is recommended as Step 2.

Step 3

If not at target on A+C: add a thiazide-like diuretic (indapamide or chlortalidone are preferred over bendroflumethiazide). “A+C+D” triple therapy.

Step 4 (Resistant Hypertension)

BP not controlled on A+C+D at optimal doses: confirm adherence and exclude secondary hypertension. If serum potassium is normal or low, add spironolactone 25mg (a potassium-sparing aldosterone antagonist; often strikingly effective for resistant hypertension due to unrecognised primary aldosteronism). If potassium is raised, add an alpha-blocker (doxazosin) or beta-blocker (bisoprolol). Refer to specialist hypertension clinic for resistant hypertension.

Blood Pressure Treatment Targets (NICE NG136)

• Clinic BP below 140/90 mmHg for most adults; ABPM/HBPM below 135/85 mmHg
• Below 130/80 mmHg in clinic (below 125/75 mmHg ABPM) for people with established cardiovascular disease, diabetes, or CKD with proteinuria
• Under 80 years: target below 140/90 mmHg; 80 years and over: target 150/90 mmHg (to avoid excessive lowering which may cause falls and syncope in frail elderly patients)

Monitoring at Home

Home blood pressure monitoring (HBPM) is recommended by NICE for monitoring treatment response. NHS-approved monitors meeting the British and Irish Hypertension Society (BIHS) validated device list criteria are recommended. Take measurements:

• Sit quietly for 5 minutes before measuring
• Take 2 measurements 1 minute apart
• Record in the morning and evening
• Bring readings to GP appointments

The BIHS has a validated device list at bihsoc.org/bp-monitors. Upper arm monitors are more accurate than wrist monitors.