Why does blood pressure drop when you stand up?
When you stand, gravity pools about 500–800 mL of blood in your legs and abdomen, briefly reducing blood returning to the heart. In healthy people, pressure sensors detect this and the autonomic nervous system tightens blood vessels and speeds the heart, restoring pressure within seconds. If this reflex is slow or weak, blood flow to the brain falls, causing dizziness, blurred vision or fainting.
Diagnosis
Blood pressure and pulse are measured after lying down for about five minutes, then at one and three minutes after standing. The 2011 international consensus definition is a sustained drop of at least 20 mmHg systolic or 10 mmHg diastolic within three minutes. In people with high blood pressure while lying down, a 30 mmHg systolic drop may be used. A delayed form appears after more than three minutes, so a tilt-table test is sometimes done.
Causes and risks
- Low fluid volume: dehydration, bleeding, prolonged bed rest
- Medications: blood pressure drugs, diuretics, alpha-blockers (prostate drugs), antidepressants, Parkinson's medications
- Nerve disorders: autonomic problems from diabetic neuropathy, Parkinson's disease, multiple system atrophy and others
In the US ARIC cohort study, orthostatic hypotension in middle age was linked to a 1.7-fold higher 13-year risk of death even after adjusting for risk factors, and reviews report associations with stroke, heart failure and atrial fibrillation.
Management
The basics: get up slowly (lying → sitting → standing), drink enough fluids, avoid large meals and heavy drinking, tense your leg muscles before standing and consider compression stockings. Doctors adjust any culprit medications, and for severe symptoms may prescribe drugs like midodrine or fludrocortisone. If you're being treated for high blood pressure, your target may need adjusting so pressure doesn't go too low.
This article is general health information and is not a substitute for diagnosis or treatment. If symptoms persist, see a doctor.
FAQ
- Is feeling lightheaded when I stand up normal?
- A brief head rush occasionally can happen to anyone, but frequent dizziness, near-fainting or falls on standing should be checked by a doctor, especially if you take blood pressure medicine.
Sources reviewed: 2026-10-25
References
- Freeman, R., et al. (2011). Consensus statement on the definition of orthostatic hypotension, neurally mediated syncope and the postural tachycardia syndrome. Clinical Autonomic Research, 21(2), 69–72.
- Rose, K. M., et al. (2006). Orthostatic hypotension predicts mortality in middle-aged adults: the ARIC Study. Circulation, 114(7), 630–636.
- Ricci, F., De Caterina, R., & Fedorowski, A. (2015). Orthostatic hypotension: epidemiology, prognosis, and treatment. Journal of the American College of Cardiology, 66(7), 848–860.