Blood pressure is expressed as two numbers: systolic pressure (the force during a heartbeat) over diastolic pressure (the force between beats). Both matter. Here's how the major medical organisations categorise the readings and what each category means for your health.
The categories
- Normal — below 120/80 mmHg; ideal for long-term cardiovascular health
- Elevated — 120–129 / below 80 mmHg; lifestyle changes recommended, no medication yet
- Stage 1 hypertension — 130–139 / 80–89 mmHg; lifestyle changes and possible medication depending on cardiovascular risk
- Stage 2 hypertension — 140/90 mmHg or above; usually requires medication alongside lifestyle changes
- Hypertensive crisis — above 180/120 mmHg; seek immediate medical attention, especially if accompanied by symptoms
- Low blood pressure (hypotension) — generally below 90/60 mmHg; significant only if causing symptoms such as dizziness or fainting
Understanding variability
Blood pressure is not a fixed number — it varies throughout the day, with activity, stress, temperature and posture. A single reading in a medical setting is less informative than the average of several readings taken at home at consistent times. White-coat hypertension — a temporary rise caused by the stress of a clinical environment — affects up to 20% of people and can lead to unnecessary treatment.
Home monitoring using a validated automated device (upper arm, not wrist) provides a far more accurate picture. Take two readings in the morning and two in the evening for a week before any clinical decision is made based solely on office readings.