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Hypotension is the medical term for low blood pressure.


The pressure of the blood in the arteries rises and falls as the heart and muscles handle demands of daily living, such as exercise, sleep and stress. Some healthy people have blood pressure well below the average for their age, even though they have a completely normal heart and blood vessels. This is often true of athletes who are in superior shape. The term "hypotension" is usually used only when blood pressure has fallen so far that enough blood can no longer reach the brain, causing dizziness and fainting.

Causes and symptoms

Postural hypotension is the most common type of low blood pressure. In this condition, symptoms appear after a person sits up or stands quickly. In normal people, the cardiovascular system must make a quick adjustment to raise blood pressure slightly to account for the change in position. For those with postural hypotension, the blood pressure adjustment is not adequate or it doesn't happen. Postural hypotension may occur if someone is taking certain drugs or medicine for high blood pressure. It also happens to diabetics when nerve damage has disrupted the reflexes that control blood pressure.
Many people have a chronic problem with low blood pressure that is not particularly serious. This may include people who require certain medications, who are pregnant, have bad veins, or have arteriosclerosis (hardening of the arteries).
The most serious problem with low blood pressure occurs when there is a sudden drop, which can be life-threatening due to widespread ischemia (insufficient supply of blood to an organ due to blockage in an artery). This type of low blood pressure may be due to a wide variety of causes, including:
  • trauma with extensive blood loss
  • serious burns
  • shock from various causes (e.g. anaphylaxis)
  • heart attack
  • adrenal failure (Addisonian crisis)
  • cancer
  • severe fever
  • serious infection (septicemia)


Blood pressure is a measure of the pressure in the arteries created by the heart contracting. During the day, a normal person's blood pressure changes constantly, depending on activity. Low blood pressure can be diagnosed by taking the blood pressure with a sphygmomanometer. This is a device with a soft rubber cuff that is inflated around the upper arm until it's tight enough to stop blood flow. The cuff is then slowly deflated until the health care worker, listening to the artery in the arm with a stethoscope, can hear the blood first as a beat forcing its way along the artery. This is the systolic pressure. The cuff is then deflated more until the beat disappears and the blood flows steadily through the open artery; this gives the diastolic pressure.
Blood pressure is recorded as systolic (higher) and diastolic (lower) pressures. A healthy young adult has a blood pressure of about 110/75, which typically rises with age to about 140/90 by age 60 (a reading now considered mildly elevated).


Treatment of low blood pressure depends on the underlying cause, which can usually be resolved. For those people with postural hypotension, a medication adjustment may help prevent the problem. These individuals may find that rising more slowly, or getting out of bed in slow stages, helps the problem. Low blood pressure with no other symptoms does not need to be treated.


Low blood pressure as a result of injury or other underlying condition can usually be successfully treated if the trauma is not too extensive or is treated in time. Less serious forms of chronic low blood pressure have a good prognosis and do not require treatment.



Smeltzer, Suzanne C., and Brenda G. Bare. Brunner and Suddarth's Textbook of Medical and Surgical Nursing. 8th ed. Philadelphia:Lippincott-Raven Publishers, 1996.

Key terms

Arteriosclerosis — A group of disorders that causes thickening and loss of elasticity in artery walls.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


diminished tension; lowered blood pressure. A consistently low blood pressure (systolic pressure less than 100 mm of mercury) usually is no cause for concern. In fact, low blood pressure often is associated with long life. However, extremely low blood pressure may be a sign of a serious condition such as shock, massive hemorrhage, hypovolemia, or severe dehydration from nausea and vomiting. In shock there is a disproportion between the blood volume and the capacity of the circulatory system, resulting in greatly reduced blood pressure. Hypotension may also be associated with addison's disease or inadequate thyroid function, but in both cases the primary disease produces so many other symptoms that the hypotension is not a major focus for concern.
orthostatic hypotension (postural hypotension) a fall in blood pressure (usually defined as a 20 to 30 point change in pulse or blood pressure), associated with dizziness, syncope, and blurred vision, occurring when a person goes from lying down or sitting to standing; it can be acquired or idiopathic, transient or chronic, and may occur alone or secondary to a disorder of the central nervous system such as the shy-drager syndrome.
supine hypotension vena caval syndrome.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


1. Subnormal arterial blood pressure. Synonym(s): hypopiesis
2. Reduced pressure or tension of any kind.
[hypo- + L. tensio, a stretching]
Farlex Partner Medical Dictionary © Farlex 2012


1. Abnormally low arterial blood pressure.
2. Reduced pressure or tension of a body fluid, as of the intraocular or cerebrospinal fluids.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


↓ BP. See Exercise hypotension, Orthostatic hypotension.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.


1. Subnormal arterial blood pressure.
Synonym(s): hypopiesis.
2. Reduced pressure or tension of any kind.
[hypo- + L. tensio, a stretching]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


Low blood pressure. This may be a feature of various serious conditions such as surgical SHOCK from massive fluid loss, or HEART FAILURE, but British and American medicine does not recognize the existence of a state of low blood pressure compatible with normal life activities. In Germany and other countries such hypotension is widely accepted. Postural hypotension is a drop in blood pressure occurring on standing up. This causes faintness or dizziness.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


1. Subnormal arterial blood pressure.
2. Reduced pressure or tension of any kind.
[hypo- + L. tensio, a stretching]
Medical Dictionary for the Dental Professions © Farlex 2012

Patient discussion about hypotension

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