What counts as high
Hypertension is blood pressure that stays high enough, often enough, to threaten the heart and vessels over years. Guidelines vary slightly, but a widely used scheme reads roughly like this: normal is below 120/80; a borderline “elevated” band sits just above; and confirmed hypertension is divided into stages by how far the numbers climb. The exact cut-points matter less than the idea behind them — risk rises smoothly with pressure, and the stages are convenient lines drawn across a continuous gradient.
A common staging (mmHg) — systolic / diastolic Normal < 120 and < 80 Elevated 120-129 and < 80 Stage 1 130-139 or 80-89 Stage 2 >= 140 or >= 90 Hypertensive crisis > 180 and/or > 120 Rule: use whichever number lands in the higher stage. A reading of 135 / 75 is Stage 1 because the systolic 135 sits in the 130-139 band, even though the diastolic 75 is normal.
When only the top number is high
In older adults a special pattern is common: the systolic number is high while the diastolic stays normal or even low. This is isolated systolic hypertension, and it reflects arteries that have stiffened with age. A stiff artery cannot cushion the pulse, so the peak (systolic) shoots up and the trough (diastolic) drops — widening the pulse pressure. It is not benign: the high systolic number still drives real risk and is worth treating.
Why we treat numbers, not symptoms
Hypertension is sometimes called the “silent” condition because most people feel completely normal. The damage is slow and quiet: year after year of extra pressure thickens the heart, scars the kidneys, and weakens vessel walls. By the time symptoms appear, target organ damage may already be done. This is why doctors stage and treat the number itself — it is a cardiovascular risk factor we can measure long before any harm is felt.