Blood pressure: the cheapest thing you can do

Raised blood pressure is among the leading contributors to death and disability worldwide, produces no symptoms until it causes damage, and is treatable with medication that costs very little.

The numbers

Blood pressure is expressed as systolic over diastolic in millimetres of mercury.

Thresholds vary between guidelines: many define hypertension as a clinic reading at or above 140/90, with lower thresholds used in some countries and for home readings.

Risk rises continuously rather than at a step, which is why the threshold is a decision point rather than a biological boundary.

A single high reading does not diagnose anything — diagnosis generally requires repeat measurement, and increasingly home or ambulatory monitoring, because clinic readings are frequently higher than true values.

White coat and masked hypertension

Two phenomena that change management.

White coat hypertension is a raised reading in a clinical setting with normal readings elsewhere, and it affects a substantial proportion of people.

Treating it as if it were sustained hypertension leads to unnecessary medication.

Masked hypertension is the reverse — normal in clinic, raised at home — and it is associated with cardiovascular risk that goes untreated.

Which is why guidance in several countries recommends confirming a raised clinic reading with ambulatory or home monitoring before starting treatment.

Measuring it properly at home

Where technique matters as much as the device.

Use a validated upper-arm monitor rather than a wrist or finger device, and check the model against a published validation list.

Use the correct cuff size, since a cuff that is too small produces falsely high readings — this is a common and significant error.

Sit quietly for five minutes beforehand, back supported, feet flat, arm supported at heart level.

Do not talk during the measurement.

Avoid caffeine, exercise and smoking for half an hour beforehand, and empty your bladder first.

Take two or three readings a minute apart and record them all.

Measure morning and evening for around a week when establishing a diagnosis, and discard the first day.

What raises it

Modifiable factors with reasonable evidence.

Salt intake, where reduction produces measurable falls, with most dietary salt coming from processed food rather than the salt cellar.

Excess weight.

Alcohol.

Physical inactivity.

Low potassium intake, which is why fruit and vegetables help.

Poor sleep and untreated sleep apnoea, which is a recognised secondary cause and is frequently missed in resistant hypertension.

Some medications, including non-steroidal anti-inflammatories, some decongestants and combined hormonal contraception.

And chronic stress, where the relationship is real and less straightforward than assumed.

Treatment and what it costs

The economics are unusually favourable.

The main drug classes — ACE inhibitors, angiotensin receptor blockers, calcium channel blockers and thiazide-type diuretics — are all available as generics costing very little per month.

Most people require more than one medication to reach target, and combination pills reduce both cost and the number of tablets.

The comparison worth making: a few pounds or dollars a month against the cost of a stroke, which is measured in hospital stays, rehabilitation, lost income and long-term care.

Adherence is the weak point — a substantial proportion of people stop taking antihypertensives within a year, largely because the condition produces no symptoms and the medication sometimes does.

Side effects and what to do about them

Since this is why people stop.

ACE inhibitors cause a dry cough in a meaningful minority, which resolves on switching to an angiotensin receptor blocker.

Calcium channel blockers cause ankle swelling.

Diuretics increase urination and can affect electrolytes.

Beta blockers can cause fatigue.

All of these are reasons to change treatment rather than to stop it, and there are enough options that almost everyone can find a tolerable combination.

The practical plan

Get it measured, at a pharmacy, a clinic or with your own validated monitor.

If raised, confirm it properly rather than acting on one reading.

Address the modifiable factors, which for some people is sufficient.

Take medication if it is offered, and report side effects rather than stopping.

Re-check at the interval advised.

And remember that the whole intervention — a monitor, a generic tablet and an annual review — costs less over a decade than a single unplanned hospital admission.

General information only, not medical advice. Consult a qualified clinician about blood pressure readings and treatment, and do not stop prescribed medication without advice.