Why does blood pressure drop when standing up?

Postural hypotension is a condition in which blood pressure suddenly drops when standing up from a sitting or lying position, causing the amount of oxygen-rich blood to the brain to decrease, causing dizziness, lightheadedness, fatigue or fainting. When standing, gravity causes blood to temporarily pool in the legs and abdomen, reducing blood flow to the heart. Pressure sensors in the arteries of the neck and near the heart detect this change, triggering a reflex that causes the heart to beat faster and blood vessels to contract, pumping blood to the brain, maintaining alertness and balance. In the elderly or people taking antihypertensive drugs or having chronic diseases, this reflex is slower, blood pressure remains lower than normal, increasing the risk of dizziness, loss of balance and falls.

Hypotension occurs when systolic blood pressure drops over 20 mmHg or diastolic blood pressure drops over 10 mmHg within 3 minutes of standing up. In addition to age, many other factors also cause blood pressure to decrease when standing, including prolonged immobility, dehydration, reduced blood volume, use of diuretics, beta blockers, or chronic diseases such as diabetes, heart failure, or neurological disorders. Therefore, maintaining enough water, limiting alcohol, exercising regularly and controlling chronic diseases help stabilize blood pressure and reduce the risk of dizziness when standing.

To prevent postural hypotension, change position from lying or sitting to standing slowly, especially after waking up or sitting for a long time. A diet full of minerals such as potassium, magnesium, calcium, eating many small meals, exercising regularly and avoiding sudden changes in temperature also helps balance blood pressure.

In addition to basic preventative measures, older people or people at high risk can wear compression stockings to support leg blood circulation, use handrails or canes when standing up, and do gentle foot and ankle exercises to improve circulation. If you are taking antihypertensive drugs, diuretics or cardiovascular drugs, you should talk to your doctor to adjust the dosage or time of use to reduce the risk of orthostatic hypotension.

Patients should see a doctor if they have serious signs such as severe headaches, sudden vision changes, difficulty speaking, paralysis of the face, arms or legs, confusion, or seizures. Regularly checking blood pressure can lead to early detection, lifestyle adjustments and timely treatment, thereby protecting long-term health and preventing dangerous complications.