Causes of High Blood Pressure

High blood pressure (hypertension) affects roughly 1 in 4 UK adults. Most cases are "primary" with no single cause — but several risk factors compound, and a small percentage are caused by underlying medical conditions.

Modifiable risk factors

Excess salt. UK adults eat ~8.4g/day on average; NHS guidance is <6g. Salt drives sodium retention and raises BP.
Excess alcohol. >14 units/week raises BP measurably. Lowering intake has fast effect.
Overweight. Each 1kg loss can drop systolic BP by ~1mmHg.
Sedentary lifestyle. 150 min/week of moderate aerobic activity reduces BP.
Smoking. Acute BP spike per cigarette; long-term vascular damage.
Stress. Chronic stress raises sustained BP. Short-term spikes from acute stress.
Poor sleep. <6 hours/night or untreated sleep apnoea raises BP.

Non-modifiable factors

Age. BP rises with age; ~70% of UK adults over 70 have hypertension.
Family history. Strong genetic component.
Ethnicity. Higher rates in UK adults of African and Caribbean heritage.
Sex. Men have higher rates until ~65; women catch up post-menopause.

Secondary hypertension

About 5-10% of hypertension cases are caused by an underlying condition: kidney disease, thyroid problems, sleep apnoea, certain medications (NSAIDs, decongestants, some contraceptives), or rare adrenal tumours. If BP is very high or rises suddenly, GP will investigate for secondary causes.

When to see a GP

If home readings are consistently >135/85 (or clinic >140/90), see your GP. Any single reading above 180/120 requires urgent assessment. Sudden severe headache, chest pain, vision change, confusion, or difficulty speaking alongside high BP — call 999.

In-depth content on each risk factor — including UK-specific NHS guidance and current NICE recommendations — is being written.

Not medical advice. This is general information. For diagnosis, monitoring, or any treatment of high blood pressure, see your GP or a qualified clinician. In an emergency call 999.