High Blood Pressure (Hypertension)
Symptoms, Causes & Treatment
Everything you need to know about high blood pressure: what causes it, why it matters, how it is diagnosed, and the lifestyle changes and medications that effectively control it.
What Is High Blood Pressure?
High blood pressure, or hypertension, is a condition in which the force of blood against the artery walls is consistently too high. It is one of the most common long-term conditions in the UK, affecting approximately 1 in 3 adults – over 14 million people – though an estimated 5 million people in the UK have undiagnosed hypertension, because the condition typically causes no symptoms.
Blood pressure is measured in millimetres of mercury (mmHg) and expressed as two figures: systolic pressure (the pressure when the heart contracts) over diastolic pressure (the pressure when the heart relaxes between beats). A reading of 120/80 mmHg is considered optimal in adults.
Hypertension is generally defined as a sustained blood pressure of 140/90 mmHg or above when measured in a clinic setting, or 135/85 mmHg or above on home or ambulatory measurement. The threshold for treatment decisions takes into account not just blood pressure level but overall cardiovascular risk.
Hypertension is often called the "silent killer" because it causes no symptoms in the vast majority of people – until it produces its devastating complications. Untreated hypertension is the single most important preventable risk factor for heart attack, stroke, heart failure, kidney disease, and dementia in the UK.
What Are the Symptoms of High Blood Pressure?
In most cases, hypertension causes no symptoms. When symptoms do occur they usually indicate very high blood pressure or organ damage.
Usually no symptoms (hypertension is the ‘silent killer’) · Headache (typically occipital, on waking) · Visual disturbances · Nosebleeds · Shortness of breath on exertion · Chest pain · Swollen ankles · Fatigue
Severe headache with blood pressure over 180/120 — hypertensive emergency · Sudden vision loss or double vision · Sudden confusion or difficulty speaking · Chest pain or breathlessness at rest — call 999
If blood pressure is above 180/120 mmHg with severe headache, visual changes, confusion, or chest pain — this is a hypertensive emergency. Call 999 immediately.
What Causes High Blood Pressure?
In 90–95% of cases, hypertension is ‘essential’ (primary) — arising from a combination of genetic predisposition and lifestyle factors. In 5–10% of cases, an underlying condition is responsible.
The most common form, caused by a complex interplay of genetics, diet, physical inactivity, obesity, and stress. No single cause is identified.
Kidney disease, renal artery stenosis, primary hyperaldosteronism, thyroid disorders, and sleep apnoea are important treatable secondary causes of hypertension.
High salt intake, obesity, excessive alcohol, physical inactivity, and chronic stress all raise blood pressure. Addressing these can normalise BP without medication in mild cases.
NSAIDs, decongestants, stimulants, combined oral contraceptive pill, and some antidepressants can raise blood pressure. A medication review may identify a reversible cause.
Chronic kidney disease raises blood pressure through fluid retention, increased renin-angiotensin activation, and sympathetic nervous system stimulation — making it a leading cause of resistant hypertension.
Primary hyperaldosteronism (Conn’s syndrome) is the most common identifiable cause of secondary hypertension. Excess aldosterone causes sodium retention, hypertension, and hypokalaemia.
Key Risk Factors
How Is High Blood Pressure Diagnosed?
A diagnosis of hypertension is confirmed after elevated clinic readings are confirmed by 24-hour ABPM. Once diagnosed, tests to assess cardiovascular risk and screen for organ damage are performed.
How Is High Blood Pressure Treated?
NICE recommends a stepwise approach starting with lifestyle measures for stage 1 low-risk disease, through to combination antihypertensive therapy for higher stages.
Supportive Measures
A DASH-style diet (rich in fruit, vegetables, low-fat dairy; low in salt and saturated fat), healthy weight, limiting alcohol to under 14 units per week, and at least 150 minutes of moderate aerobic exercise weekly all meaningfully reduce blood pressure.
Resistant Hypertension
Resistant hypertension is blood pressure above target despite three agents at optimal doses. This requires exclusion of white coat effect, medication adherence check, secondary cause investigation, and possible spironolactone or specialist referral.
When Should You Seek Medical Advice?
Blood pressure is above 180/120 mmHg with symptoms · Sudden severe headache, vision changes, confusion, or chest pain with known hypertension — call 999.
Your blood pressure is consistently above 140/90 mmHg · You have been told you have hypertension but are not on treatment · Your medication does not appear to be controlling your reading · You have headaches and have not had your BP checked recently.
How Can You Prevent or Lower High Blood Pressure?
Lifestyle modification is both prevention and treatment for hypertension.
Reduce salt to under 6g/day, follow a DASH-style diet, limit alcohol, achieve a healthy weight, and take regular aerobic exercise. These measures can lower blood pressure by 5–10 mmHg.
Have your blood pressure checked at least every 5 years if normal, or annually if above optimal. Hypertension has no symptoms — early detection saves lives.
Home blood pressure monitoring allows tracking of response to treatment between clinic visits. Target a home reading below 135/85 mmHg. Take readings twice daily for at least a week before any clinical review.
Reduce dietary salt to under 6g (1 teaspoon) per day. Avoid high-salt processed foods, tinned products, bread, and ready meals. Check labels — many foods contain hidden salt.
Limit alcohol to no more than 14 units per week for both men and women, spread over at least 3 days. Excessive alcohol is an independent and significant cause of hypertension and resistance to treatment.
Stop smoking — this is the single most impactful intervention for reducing cardiac chest pain risk. Smoking cessation reduces cardiovascular risk by 50% within one year regardless of duration of prior smoking.
Speak to a Clinician About High Blood Pressure
Through The GP Service you can discuss your blood pressure readings with a licensed clinician, receive a medication review or prescription, and get guidance on monitoring — without a waiting room.
Expert clinical advice, when you need it.
Hypertension FAQs
The UK guideline threshold for diagnosing hypertension is a clinic reading of 140/90 mmHg or above, confirmed by ABPM (ambulatory blood pressure monitoring) showing a daytime average of 135/85 mmHg or above. Stage 2 hypertension is diagnosed at 160/100 mmHg or above (clinic) or 150/95 mmHg (ABPM). The threshold for drug treatment depends on stage and overall cardiovascular risk. Some people with stage 1 hypertension may be managed with lifestyle changes alone if their 10-year cardiovascular risk is low.
Many cases of hypertension can be significantly improved with lifestyle changes alone, particularly in stage 1 disease in people without high cardiovascular risk. Weight loss, dietary salt reduction, exercise, alcohol reduction, and smoking cessation each independently lower blood pressure. However, for most people with sustained hypertension above 160/100 mmHg or with cardiovascular risk factors, medication is required alongside lifestyle measures. Blood pressure medication is generally safe, well-tolerated, and can be taken indefinitely.
Yes. Left ventricular hypertrophy (LVH) — thickening of the heart wall due to the increased work of pumping against high blood pressure — is a significant hypertension complication detectable on ECG or echocardiogram. Target organ damage from hypertension also affects the kidneys (hypertensive nephropathy — microalbuminuria, reduced eGFR), eyes (hypertensive retinopathy), and brain (white matter changes, lacunar infarcts). Checking for target organ damage at diagnosis and monitoring annually ensures appropriate treatment intensity.
Yes. Hypertension in pregnancy — particularly pre-eclampsia (hypertension with proteinuria after 20 weeks) — is a serious condition affecting 2–5% of pregnancies. It can cause maternal complications (seizures, stroke, organ failure) and fetal growth restriction or preterm birth. Safe antihypertensives in pregnancy include labetalol, nifedipine, and methyldopa. ACE inhibitors and ARBs must be avoided in pregnancy due to fetal toxicity. Women with pre-existing hypertension should have their medication reviewed before or at the start of pregnancy.
A stroke is the most serious complication of untreated AF. Additionally, longstanding uncontrolled AF can cause AF-induced cardiomyopathy — a weakening of the heart muscle due to persistently fast, irregular rates. Hypertensive heart disease is the most common cause of hospitalisation in uncontrolled high blood pressure. Aortic dissection (a tear in the main blood vessel from the heart) is a rare but catastrophic complication of chronic severe hypertension. These risks underscore why treating both AF and hypertension is a cardiovascular priority.
Ectopic beats feel like a ‘thump’, ‘flip-flop’, or ‘missed beat’ in the chest. They occur when the heart produces an extra beat earlier than expected, followed by a compensatory pause. This pause is what creates the thumping sensation. Ectopic beats are extremely common — most people experience them at some point — and are almost always benign in people with structurally normal hearts. They often worsen when lying in bed, at rest, or after caffeine. While distressing, they are not dangerous in most people. Reassurance, trigger avoidance, and (if severe) beta-blockers are the management options.
Atrial fibrillation (AF) produces an irregularly irregular heart rhythm — the heartbeat has no pattern and is completely unpredictable. This is distinct from regular fast rhythms (SVT) or extra beats (ectopics). AF carries a significantly elevated stroke risk because blood can pool in the left atrial appendage and form clots. This is why anticoagulation with apixaban, rivaroxaban, or warfarin is a central part of AF management. The CHA₂DS₂-VASc score calculates your individual stroke risk and determines whether anticoagulation is indicated. All patients with AF should have this risk formally assessed.
Rate control aims to reduce the heart rate in AF to below 110bpm at rest (usually with beta-blockers or rate-limiting calcium channel blockers like diltiazem) without necessarily restoring sinus rhythm. Rhythm control aims to restore and maintain normal sinus rhythm using antiarrhythmic drugs (flecainide, amiodarone) or cardioversion/catheter ablation. Both strategies are effective. Rhythm control is now preferred for younger patients and those with symptoms, as it offers a better quality of life and may reduce long-term complications.