# What Causes High Blood Pressure? A UK Guide

Published: 2026-06-08

What Causes High Blood Pressure? A UK Guide (2026) | Matter

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Blood Pressure

# What Causes High Blood Pressure? A UK Guide

In about 90 to 95 percent of UK cases, there is no single identifiable cause. The rest have a specific medical driver, and the distinction matters because the treatment path is different. Here is what the NHS, NICE and the published research say about both routes, and what you can act on.

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Medically reviewed by Dr. Nouman Kazmi, MBBS FCPS](https://getmatter.co/pages/matter-cardiologist-dr-syed-nouman-kazmi "View reviewer profile")
·
10 min read

~90%

Primary hypertension (no single cause)

5–10%

Secondary (identifiable cause)

8.4g

UK average daily salt (target: 6g)

1 in 3

UK adults affected

## Key Takeaways

* Around 90 to 95 percent of UK hypertension is "primary" (or "essential"), meaning there is no single identifiable cause. It develops over years from a combination of factors.
* The remaining 5 to 10 percent is "secondary": caused by a specific condition (kidney disease, hormonal disorders, sleep apnoea) or medication.
* The main modifiable drivers of primary hypertension are diet (especially salt), body weight, alcohol intake, physical inactivity, smoking, and chronic stress.
* Non-modifiable factors include age, family history, ethnicity, and sex. These shape your baseline risk but not your day-to-day numbers.
* Stress and anxiety can raise blood pressure temporarily, but they are rarely the sole cause of sustained hypertension on their own.
* If your GP suspects a secondary cause, expect blood tests, a urine test, and sometimes imaging or referral to a specialist.

In This Article

1. [Primary vs secondary: the 90/10 split](#primary-vs-secondary)
2. [The drivers of primary hypertension](#primary-drivers)
3. [What causes secondary hypertension](#secondary-causes)
4. [Stress, anxiety and what people often confuse with "cause"](#stress-anxiety)
5. [What you can actually do about the modifiable drivers](#modifiable)
6. [When to talk to your GP](#gp)
7. [When high blood pressure is urgent](#urgent)
8. [Frequently asked questions](#faq)

## Primary vs Secondary: The 90/10 Split

When a UK GP diagnoses someone with high blood pressure, the first question they are quietly weighing is which of two routes brought you here. Around 90 to 95 percent of cases are **primary hypertension** (also called essential hypertension). The remaining 5 to 10 percent are **secondary**: caused by a specific medical condition or medication. The treatment path is different, so the distinction matters.

**Primary hypertension** has no single identifiable cause. It develops gradually over years, shaped by a combination of age, family history, body weight, diet (particularly salt and alcohol), physical activity, and other lifestyle factors. The relevant [NICE guideline NG136](https://www.nice.org.uk/guidance/ng136/chapter/recommendations) calls this the "essential" form for a reason: there is no underlying disease driving it, so the management is long-term lifestyle change first, then medication if readings remain elevated.

**Secondary hypertension** has a specific, identifiable cause. The most common in the UK are kidney disease, hormonal disorders, obstructive sleep apnoea, and a handful of medications. Treating the underlying cause often brings blood pressure back down, sometimes to normal. NICE recommends investigating for a secondary cause if you are under 40 with sudden onset, if your readings do not respond to first-line treatment, or if your blood tests show certain patterns (low potassium, abnormal kidney function).

Which type someone has shapes the conversation entirely. Primary hypertension is a long-term cardiovascular risk factor managed across decades. Secondary hypertension can sometimes be reversed in months by treating the condition causing it. The rest of this guide walks through both, starting with primary because that is the overwhelming majority.

0%

**Of UK hypertension is primary, meaning there is no single cause to remove.** Management is lifestyle change first and medication if readings stay high. The 5 to 10 percent that is secondary may improve when the underlying condition is treated.

## The Drivers of Primary Hypertension

Primary hypertension is not random. It is the cumulative result of a handful of well-studied factors. NICE, the British Heart Foundation, and the Lancet Hypertension Commission group them into roughly the same categories. Some are modifiable, some are not.

### Age and arterial stiffness

Arteries lose elasticity with age. Collagen replaces some of the elastin in the artery walls, and they become less able to absorb the force of each heartbeat. The result is a rising systolic number from middle age onwards. Production of nitric oxide, the molecule that helps blood vessels relax, drops by roughly half between ages 25 and 60. This is the single biggest reason hypertension prevalence climbs steeply after 50.

### Family history and genetics

If a parent or sibling has high blood pressure, your own risk is higher. Twin studies put the heritability of blood pressure at roughly 30 to 50 percent. There is no single "hypertension gene": dozens of common variants each contribute a small amount. This means family history shapes your baseline but does not determine your trajectory.

### Salt intake

The UK adult averages around 8.4g of salt per day, well above the NHS target of 6g. According to SACN (the Scientific Advisory Committee on Nutrition), salt is one of the strongest dietary drivers of population blood pressure. Cutting intake by 2 to 3g per day produces a measurable systolic drop of 4 to 5 mmHg in most adults, and a larger drop in people who are already salt-sensitive.

### Body weight

Excess weight, particularly around the waist, drives blood pressure up through a combination of hormonal, metabolic, and mechanical effects. The relationship is dose-dependent: on average, every 1kg above a healthy weight adds around 1 mmHg of systolic pressure. A 5 percent loss of body weight produces a measurable drop in most overweight adults.

### Alcohol

Regular intake above 14 units per week (the NHS guideline) raises blood pressure. The effect appears to be dose-dependent and reversible. Reducing from heavy to moderate drinking lowers systolic pressure by 4 to 5 mmHg within weeks. Binge drinking on weekends can also cause sustained mid-week elevation.

### Physical inactivity

Adults who do less than 150 minutes per week of moderate-intensity activity (brisk walking counts) have measurably higher blood pressure on average. Regular activity improves the elasticity of blood vessel walls and supports healthy nitric oxide production. The lower bar than most people expect: walking 30 minutes a day, five days a week, is the threshold.

### Smoking, sleep, and stress

Smoking is a direct vasoconstrictor and a long-term driver of arterial stiffness. Chronic short sleep (under 6 hours per night) elevates daytime blood pressure. Chronic stress contributes mostly through behavioural pathways (poor sleep, alcohol, comfort eating) rather than direct mechanism. None of these on their own usually cause sustained hypertension, but they stack with the others.

## What Causes Secondary Hypertension

In about 5 to 10 percent of UK cases, high blood pressure has a specific, identifiable cause. These are worth knowing about because some are reversible: treat the underlying condition and blood pressure often returns to or near normal.

### Kidney disease

The kidneys regulate fluid balance and the renin-angiotensin system, both of which influence blood pressure. Chronic kidney disease (CKD) and renovascular disease (narrowing of the renal arteries) are the most common renal causes. A simple blood test (creatinine, eGFR) and a urine test (for protein and blood) are usually the first investigations.

### Hormonal disorders

Several endocrine conditions raise blood pressure. The main ones are primary aldosteronism (Conn's syndrome), Cushing's syndrome, phaeochromocytoma, and thyroid disorders (both over- and underactive). Primary aldosteronism is the most common, and screening with an aldosterone-to-renin ratio is recommended by NICE when readings are resistant to treatment or potassium is low.

### Obstructive sleep apnoea

Repeated dips in overnight oxygen levels drive sympathetic nervous system activation and sustained daytime blood pressure elevation. Sleep apnoea is under-diagnosed in the UK and is worth ruling out, particularly if you snore heavily, wake unrefreshed, or your partner has noticed you stop breathing in your sleep. Treating with CPAP often brings blood pressure down within months.

### Medications that raise blood pressure

Several common medicines can push readings up. NSAIDs (ibuprofen, naproxen, diclofenac) used regularly. Decongestants containing pseudoephedrine. The combined oral contraceptive pill in some women. Corticosteroids. Some antidepressants (venlafaxine, MAOIs). Liquorice in large quantities. If a new medication has coincided with rising blood pressure, mention it to your GP: a switch may be all that is needed.

### Pregnancy

Gestational hypertension and pre-eclampsia are specific to pregnancy and require their own monitoring. Both usually resolve after delivery but increase long-term cardiovascular risk and warrant follow-up.

⚠

When to suspect a secondary cause

NICE suggests investigating for a secondary cause if you are under 40 with sudden onset, if readings remain elevated despite three or more medications at adequate doses, or if blood tests show low potassium or abnormal kidney function. Most cases are still primary, but the threshold for investigation is low because some secondary causes are reversible.

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## Stress, Anxiety and What People Often Confuse with "Cause"

One of the most common questions UK GPs hear is whether stress alone caused someone's high blood pressure. The honest answer is more layered than yes or no.

**Acute stress** (a stressful phone call, running for the bus, a difficult conversation) raises blood pressure temporarily. This is normal and adaptive. The numbers settle within minutes once the stressor passes. A single high reading taken under stress is not a diagnosis.

**Chronic stress** is more complicated. It contributes to high blood pressure mostly through behavioural pathways (disrupted sleep, drinking more, comfort eating, less activity) rather than as a direct cause. Chronic stress on its own rarely produces sustained hypertension in someone whose other risk factors are well managed. It stacks with them rather than replacing them.

**White coat hypertension** is a recognised phenomenon: readings rise in clinic settings but stay normal at home. NICE addresses this by recommending either ambulatory blood pressure monitoring (a 24-hour cuff) or 7 days of home monitoring before diagnosis, rather than relying on a single clinic reading. Around 15 to 25 percent of people show some white coat effect.

**Anxiety and panic attacks** cause real spikes but rarely cause sustained primary hypertension on their own. If your home readings outside anxious moments are normal, you do not have hypertension by NICE's definition, even if your clinic numbers look high.

**Caffeine** raises blood pressure for one to three hours after a strong dose. Regular coffee drinkers develop partial tolerance. There is no good evidence that habitual coffee intake at normal amounts causes sustained hypertension in adults without other risk factors.

The "I don't feel stressed, so why is my blood pressure high?" question gets asked often. Primary hypertension is usually silent. There is no felt sensation that maps to the number on the cuff. [Our guide on symptoms of high blood pressure](https://getmatter.co/blogs/heart-health/symptoms-of-high-blood-pressure-what-to-look-for) covers what you might and might not notice.

## What You Can Actually Do About the Modifiable Drivers

Of the primary hypertension drivers, the ones that move the needle most reliably when acted on are salt, weight, activity, alcohol, and diet pattern. Here is the order of magnitude for each, based on the published meta-analyses NICE and the Cochrane Collaboration draw on.

### Cut salt to 6g or below

Reducing daily salt from the UK average of around 8.4g to the NHS target of 6g produces roughly a 4 to 5 mmHg drop in systolic pressure. Most of the salt comes from processed foods (bread, cereals, ready meals, takeaways), not the salt shaker. Checking labels for sodium content is more useful than avoiding the table salt.

### Adopt a DASH-style eating pattern

The DASH (Dietary Approaches to Stop Hypertension) pattern emphasises vegetables, fruit, whole grains, lean protein and lower-fat dairy. Trials show systolic drops of 8 to 14 mmHg, and the effect appears within weeks. It does not require anything exotic. More vegetables, less processed food, modest portions of red meat.

### Move 150 minutes per week

Adults who do 150 minutes per week of moderate-intensity activity (brisk walking counts) average 5 to 8 mmHg lower systolic pressure than sedentary peers. The threshold is roughly 30 minutes a day, five days a week. Isometric exercise (wall sits, handgrip) has shown the largest BP drop of any modality in recent meta-analyses.

### Lose 5 percent of body weight if overweight

A 5 percent reduction in body weight produces a measurable systolic drop in most adults with a BMI above 25. The effect is dose-dependent: more weight lost, more pressure dropped, up to a point. Combined with the other changes above, the cumulative effect can be substantial.

### Bring alcohol within the NHS guideline

Cutting from heavy intake (above 14 units per week) to within the guideline drops systolic pressure by 4 to 5 mmHg within weeks. Spreading drinks across multiple days matters: bunching them into two or three sessions still raises mid-week readings.

### Consider evidence-based dietary nitrate

Randomised trials show dietary nitrate (the active compound in beetroot) produces a 3 to 10 mmHg systolic drop, working through the nitric oxide pathway. For more on the format choice and what to look for on a label, see our [UK buyer's guide to beetroot supplements](https://getmatter.co/pages/best-beetroot-supplement-uk).

None of these is a magic fix on its own. Stacked, the published evidence supports 15 to 25 mmHg of cumulative systolic drop, which is enough to bring most cases of mild-to-moderate hypertension into a healthy range without medication. For the broader treatment of the lifestyle side, see our deeper guide to [how to lower blood pressure naturally](https://getmatter.co/blogs/heart-health/how-to-lower-blood-pressure-naturally).

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## When to Talk to Your GP

For most adults with a borderline or moderately elevated home reading, the right next step is a GP appointment with two weeks of self-monitoring data in hand. Walking in with a printed log changes the conversation entirely: instead of taking a single clinic reading and starting again, your GP can interpret a trend.

### Don't wait for symptoms

Primary hypertension is usually silent. Most people with elevated readings feel exactly as they always have. NICE explicitly cautions against waiting for symptoms to develop, because by the time they do (headaches, breathlessness, visual changes) the readings are usually severe.

### What to bring

A home monitoring log: two readings in the morning (before medication and food) and two in the evening, at the same times each day, for at least 7 days (ideally 14). Discard day 1. The average of the rest is your baseline. Our guide on [how to measure blood pressure correctly at home](https://getmatter.co/blogs/heart-health/how-to-measure-blood-pressure-correctly-at-home) covers the technique in detail.

### What the GP will assess

Repeat measurement in clinic, ABPM (24-hour cuff) or further home monitoring if there is uncertainty, then a QRISK3 calculation of your 10-year cardiovascular risk (this factors in age, sex, ethnicity, cholesterol, family history, and other conditions). Blood tests for kidney function, electrolytes, cholesterol and HbA1c. A urine test for protein. The result is a picture of overall risk, not just a number.

### If a secondary cause is suspected

Additional tests follow: aldosterone-renin ratio (for primary aldosteronism), cortisol screening (for Cushing's), thyroid function, and sometimes a sleep study or imaging of the kidneys and adrenal glands. Referral to a hypertension specialist or relevant clinic happens if the initial workup suggests a specific cause.

### The treatment path

For Stage 1 hypertension without other cardiovascular risk factors or organ damage, NICE recommends lifestyle changes first. Medication is considered if readings remain elevated despite a sustained period of changes, or if the QRISK3 result places you above the treatment threshold. Two people with identical blood pressure can end up on quite different plans.

## When High Blood Pressure Is Urgent

Most cases of high blood pressure develop over years and are managed by appointment, not by ambulance. But there are situations where a reading requires immediate medical attention, and it is important to know the difference before you ever need to act on it.

⚠

**Seek urgent medical help if:**

* Your reading is **180/120 mmHg or above**. This is considered a hypertensive crisis.
* You experience sudden severe headache alongside a high reading.
* You have chest pain, shortness of breath, or palpitations.
* You notice visual changes such as blurred vision, double vision, or loss of vision in one eye.
* You feel suddenly confused, have difficulty speaking, or experience weakness on one side of your body. These may indicate stroke. Call 999 immediately.
* You develop nosebleeds that will not stop alongside very high readings.

If your blood pressure is very high but you have no symptoms, sit, rest for five minutes, then take another reading. If it remains above 180/120, **call NHS 111** for advice. If you experience any of the symptoms listed above alongside a high reading, **call 999**. Do not drive yourself to the hospital.

For a more detailed look at what symptoms can accompany high blood pressure, see our guide: [Symptoms of High Blood Pressure: What to Look For](https://getmatter.co/blogs/heart-health/symptoms-of-high-blood-pressure-what-to-look-for).

## Frequently Asked Questions

What is the most common cause of high blood pressure?

In around 90 to 95 percent of UK cases, high blood pressure is "primary" (or essential) hypertension, meaning it has no single identifiable cause. It develops gradually over years from a combination of age, family history, body weight, diet (particularly salt and alcohol), physical activity, and stress. Salt intake is one of the most studied dietary drivers. The remaining 5 to 10 percent has a specific cause such as kidney disease, hormonal disorders, sleep apnoea, or certain medications.

Can stress alone cause high blood pressure?

Acute stress raises blood pressure temporarily but the numbers settle once the stressor passes. Chronic stress contributes mostly through behavioural pathways (poor sleep, drinking more, less activity, comfort eating) rather than as a direct cause. On its own, stress rarely produces sustained primary hypertension in someone whose other risk factors are well managed, but it stacks with them.

Is high blood pressure genetic?

Partly. Twin studies put the heritability of blood pressure at roughly 30 to 50 percent. There is no single "hypertension gene": dozens of common variants each contribute a small amount, and the effect depends on lifestyle and environment. A family history raises your baseline risk but does not lock in your trajectory. People with strong family histories who manage the modifiable drivers often stay within healthy ranges.

Does salt cause high blood pressure?

High salt intake is one of the strongest dietary drivers of population blood pressure. SACN and the WHO both flag it as a primary lever. UK adults average around 8.4g per day, well above the NHS target of 6g. Cutting intake by 2 to 3g per day produces a measurable systolic drop of 4 to 5 mmHg in most adults, and more in people who are salt-sensitive. Most of the salt people consume comes from processed foods, not the salt shaker.

Can high blood pressure be reversed?

Secondary hypertension is sometimes reversible: treating the underlying condition (sleep apnoea, primary aldosteronism, a medication side effect) can bring blood pressure back to normal. Primary hypertension is usually managed rather than reversed, but mild-to-moderate cases can be brought back into a healthy range with sustained lifestyle changes alone. The combined published evidence supports 15 to 25 mmHg of cumulative systolic drop from stacking the major modifiable changes.

Can a urinary tract infection cause high blood pressure?

A urinary tract infection can temporarily raise blood pressure through the body's general stress response to infection and pain. The numbers usually settle once the infection is treated. A persistent UTI or recurring kidney infection that has caused kidney damage is a different matter, because chronic kidney disease is one of the more common causes of secondary hypertension. If you have ongoing kidney issues alongside raised readings, mention it to your GP.

Does drinking water lower blood pressure?

Drinking water keeps you hydrated, which helps with overall cardiovascular function, but it does not directly lower blood pressure in any meaningful way for someone already drinking enough. Severe dehydration can affect readings (usually by raising heart rate and concentrating blood). The popular advice to drink more water as a hypertension treatment is overstated. Salt reduction, weight management, activity, and alcohol moderation move the needle far more.

Can anxiety cause high blood pressure?

Anxiety and panic attacks cause real, sometimes substantial, blood pressure spikes. They rarely cause sustained primary hypertension on their own. If your home readings outside anxious moments are normal but clinic readings are high, this is white coat hypertension, which NICE recognises and addresses by using either ambulatory monitoring or 7 days of home readings before diagnosis. Treating the anxiety is worthwhile in its own right, but it is rarely the full hypertension picture.

## Continue Learning

[📊

Understand Your Numbers

What Is a Normal Blood Pressure Reading for Your Age?](https://getmatter.co/blogs/heart-health/normal-blood-pressure-by-age)
[💋

Measuring & Tracking

How to Measure Blood Pressure Correctly at Home](https://getmatter.co/blogs/heart-health/how-to-measure-blood-pressure-correctly-at-home)
[🌿

Natural Approaches

How to Lower Blood Pressure Naturally: A UK Guide](https://getmatter.co/blogs/heart-health/how-to-lower-blood-pressure-naturally)
[📚

Complete Guide

The Complete Guide to Understanding Blood Pressure (UK)](https://getmatter.co/blogs/heart-health/the-complete-guide-to-understanding-blood-pressure-uk)
[⚠

Warning Signs

Symptoms of High Blood Pressure: What to Look For](https://getmatter.co/blogs/heart-health/symptoms-of-high-blood-pressure-what-to-look-for)

---

**Medically reviewed by Dr Nouman Kazmi**
Cardiovascular Specialist & Interventional Cardiologist, UK. Dr Kazmi reviews all clinical content on the Matter Heart Health Resource Centre for accuracy and compliance with current UK guidelines.

[View Dr Kazmi's profile →](https://getmatter.co/pages/matter-cardiologist-dr-syed-nouman-kazmi)

---

## References

1. NICE. Hypertension in adults: diagnosis and management (NG136). Available at: [nice.org.uk/guidance/ng136](https://www.nice.org.uk/guidance/ng136)
2. NHS. High blood pressure (hypertension) overview. Available at: [nhs.uk](https://www.nhs.uk/conditions/high-blood-pressure-hypertension/)
3. British Heart Foundation. High blood pressure: causes and risk factors. Available at: [bhf.org.uk](https://www.bhf.org.uk/informationsupport/risk-factors/high-blood-pressure)
4. Scientific Advisory Committee on Nutrition (SACN). Salt and Health. Available at: [gov.uk](https://www.gov.uk/government/publications/sacn-salt-and-health-report)
5. Action on Salt. UK Sodium Intake Survey. Available at: [actiononsalt.org.uk](https://www.actiononsalt.org.uk/)
6. World Health Organization. Global Report on Hypertension: The Race Against a Silent Killer. 2023. Available at: [who.int](https://www.who.int/publications/i/item/9789240081062)
7. He FJ, Li J, MacGregor GA. Effect of longer term modest salt reduction on blood pressure: Cochrane systematic review and meta-analysis. *BMJ*. 2013;346:f1325.
8. Williams B, Mancia G, et al. 2018 ESC/ESH Guidelines for the management of arterial hypertension. *European Heart Journal*. 2018;39(33):3021–3104.
9. Siervo M, Lara J, Ogbonmwan I, Mathers JC. Inorganic nitrate and beetroot juice supplementation reduces blood pressure in adults: a systematic review and meta-analysis. *J Nutr*. 2013;143(6):818–826.
10. NHS. Salt: the facts. Eat well guide. Available at: [nhs.uk](https://www.nhs.uk/live-well/eat-well/food-types/salt-nutrition/)

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