What the two numbers mean, what counts as high, how to measure properly at home, and why treatment usually continues even after the readings come down.
Blood pressure is written as two numbers — 130/80, say. The first is the pressure while the heart is contracting. The second is the pressure while it relaxes and refills. Both matter, and in adults over 50 the first number tends to carry more weight.
What counts as high
In most adults, blood pressure measured in a clinic is considered high when it is consistently at or above 140/90 mmHg. Home readings are generally a little lower, so the equivalent home threshold is around 135/85.
The word doing the work in that sentence is consistently. A single high reading, taken after rushing to an appointment in the heat, is not hypertension. Diagnosis rests on repeated readings across separate occasions, and often on home or 24-hour monitoring.
- Normal 90–119 mmHgUnder 120, with a diastolic under 80.
- Elevated 120–129 mmHgNot yet hypertension, but it tends to rise from here.
- Stage 1 130–139 mmHgUsually managed first with diet, activity and salt.
- Stage 2 140 mmHg and aboveMedication is usually discussed at this point.
| Band | Range | Note |
|---|---|---|
| Normal | 90–119 mmHg | Under 120, with a diastolic under 80. |
| Elevated | 120–129 mmHg | Not yet hypertension, but it tends to rise from here. |
| Stage 1 | 130–139 mmHg | Usually managed first with diet, activity and salt. |
| Stage 2 | 140 mmHg and above | Medication is usually discussed at this point. |
Source — ACC/AHA 2017 Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults
- Normal 50–79 mmHg
- Stage 1 80–89 mmHgStage 1 is reached on either number alone.
- Stage 2 90 mmHg and above
| Band | Range | Note |
|---|---|---|
| Normal | 50–79 mmHg | |
| Stage 1 | 80–89 mmHg | Stage 1 is reached on either number alone. |
| Stage 2 | 90 mmHg and above |
Source — ACC/AHA 2017 Guideline for the Prevention, Detection, Evaluation and Management of High Blood Pressure in Adults
The category is set by whichever number is worse, not by both together. A reading of 118/94 is stage 2 hypertension on the strength of the lower number alone, even though the upper one is entirely normal.
Why it is worth treating something you cannot feel
Almost nobody feels high blood pressure. There is no reliable symptom, and headaches are a poor guide. What it does instead is work quietly: thickening the heart muscle, accelerating deposits in the arteries, straining the kidneys, and raising stroke risk more than any other single factor.
None of that produces a sensation until it produces an event. That is the entire argument for measuring rather than waiting to feel unwell.
Measuring properly at home
Home readings are frequently more useful than clinic readings, but only if they are taken correctly. Most home readings people bring to clinic are taken in ways that make them unreliable.
- 01Use an upper-arm cuff monitor, not a wrist device. Check the cuff size fits your arm.
- 02Sit for five minutes first, with your back supported and both feet flat on the floor.
- 03Rest the arm on a table so the cuff is at the level of your heart.
- 04Do not talk, and do not check your phone, during the reading.
- 05Take two readings a minute apart, and record both. Morning and evening is a good pattern.
- 06Do not measure immediately after tea, coffee, tobacco or exercise.
Why the medicine continues after the numbers normalise
This is the commonest reason blood pressure control is lost. The readings improve, the person concludes the problem has resolved, and the tablet is stopped. But the readings are normal because of the treatment, not instead of it. Pressure typically returns to its previous level within weeks.
There are genuine situations where treatment can be reduced or withdrawn — substantial weight loss, stopping heavy alcohol intake, or treating sleep apnoea can all change the underlying picture. That decision belongs with the doctor who can see the trend, and it is made by reducing gradually while monitoring, not by stopping.