How long does it take for high blood pressure to damage your body ?

Depends how↑ ; long: Keep in mind the all non-invasive BP checks are only of a single heartbeat for systolic (top) ; a different heartbeat for diastolic (bottom) ; that the digital (oscillometric) BP meters only guess at BP ; are notoriously inaccurate compared to a hg meter ; an experienced, careful human. Desirable resting sbp is <120 mmhg ; lower for best long term cv ; other organ system health.

Depends how high: It all depends on how high the blood pressure: a systolic of >180 or a diastolic >110 puts a person at risk of blood vessel injury immediately and is a medical emergency. Any hypertension lower than that typically takes years -- decades -- to cause damage to your blood vessels or organs (heart, brain, kidneys, and eyes).