Measuring Blood Pressure
Reviewed
A blood pressure measurement is a test that measures the force of blood against artery walls as the heart pumps. It is used to screen for high blood pressure (hypertension) and sometimes to check for low blood pressure (hypotension). The test is quick, noninvasive, and often part of a routine checkup.
Preparation and collection
Avoid exercise, alcohol, tobacco, and food or drinks containing caffeine for at least 30 minutes before the test. Empty your bladder before the test. Tell your provider about any medicines you take, as some may affect results.
Understanding this test
Use the reference interval and units printed by the laboratory that performed the test. A result outside that interval is not a diagnosis by itself, and a result inside it does not rule out every condition. Your symptoms, history, medicines, timing, and related tests can change what the result means.
- A single high reading does not mean you have high blood pressure; diagnosis usually requires two or more high readings on different days.
- Nervousness about having blood pressure taken at a provider's office (white coat syndrome) can cause a temporary rise in blood pressure, making results less accurate.
- The test measures pressure at one moment and can vary based on activity, stress, or time of day.
- For children under 13, results are compared to age-, sex-, and height-specific norms, which may not be directly comparable to adult categories.
What to do next
If you are diagnosed with high blood pressure, your provider may recommend lifestyle changes such as regular physical activity, maintaining a healthy weight, eating a heart-healthy diet (e.g., DASH eating plan), reducing salt intake, limiting alcohol, quitting smoking, managing stress, and getting enough sleep. You may also be advised to check your blood pressure at home using an automated monitor. For low blood pressure, treatments may include medicines and dietary changes. Always follow your provider's guidance.