Why a single reading is not enough
Blood pressure changes throughout the day in response to physical activity, emotions, sleep and other factors. An isolated high reading does not necessarily establish persistent hypertension. Results should be interpreted using a standardised technique and, when appropriate, confirmed with measurements at home or 24-hour ambulatory monitoring.
Measuring blood pressure at home
A validated automatic upper-arm monitor with an appropriately sized cuff is preferable. For 30 minutes beforehand, avoid smoking, caffeine and exercise where possible. Empty your bladder and sit quietly for around five minutes. Support your back, keep both feet on the floor with your legs uncrossed, and rest your arm at heart level. Do not talk during the measurement.
Take two readings approximately one minute apart and record both. For a planned home assessment, follow the schedule recommended by your clinician: this often involves morning and evening measurements for at least three days, preferably seven. Your clinician will interpret the average in its clinical context.
Smartwatches do not replace a validated cuff
The 2025 AHA/ACC guideline advises against relying on cuffless devices, including smartwatches, for blood pressure assessment until their accuracy and reliability are adequately established. Use a validated upper-arm cuff for clinical decisions.
AHA/ACC 2025 — blood pressure measurement recommendations
Which arm should you use?
At the initial assessment, it is useful to measure blood pressure in both arms. If a difference persists, subsequent readings are generally taken in the arm with the higher values, following clinical advice. Older adults, people with diabetes and those with symptoms on standing may also need standing blood pressure measurements to assess for orthostatic hypotension.
Office readings and home readings
Measurements in the clinic are essential but can be affected by the white-coat effect. Conversely, some people have normal readings during an appointment but higher blood pressure in everyday life: this is known as masked hypertension. Twenty-four-hour monitoring also provides information about night-time readings and the daily pattern.
Repeated very high readings without symptoms
If systolic pressure is above 180 mmHg or diastolic pressure above 120 mmHg and there are no warning symptoms, wait at least one minute and measure again. If it remains that high, contact a healthcare professional immediately. Chest pain, neurological symptoms or severe breathlessness require emergency help; do not delay it to take repeated readings.
More than a number
Blood pressure should be interpreted alongside age, cardiovascular risk, kidney function, diabetes, frailty and treatment tolerability. Targets should be individualised. Accurate measurement is the first step towards avoiding both undertreatment and excessive treatment.
Read the English guide to hypertension →
Understanding your readings
Continue with the hypertension guide to understand how blood pressure is assessed. For the wider prevention picture, read cardiovascular risk and SCORE2.
About Massimo Fioranelli · Cardiology and internal medicine · Clinical practice at Sanatrix, Rome
Further reading
ESC 2024 — Elevated Blood Pressure and Hypertension
ValidateBP — validated blood pressure monitors
American Heart Association — Home Blood Pressure Monitoring
Read the original Italian guide
Patient information, October 2026. This guide does not replace individual medical assessment.