What is low blood pressure?

Blood pressure is the measure of pressure of the blood inside arteries when your heart pumps (systolic pressure) and when it is at rest (diastolic pressure). Although there are thresholds for defining high blood pressure, or hypertension, there are no specific thresholds for defining low blood pressure, or hypotension. Instead, blood pressure is considered too low if it causes symptoms.

Three main types of low blood pressure exist: orthostatic hypotension, neurally mediated hypotension, and hypotension linked to shock. Orthostatic hypotension occurs when your blood pressure drops when you sit up or stand up after lying down and can be accompanied by such symptoms as dizziness or feeling faint. Your circulatory system is usually able to adjust to the change in position and restore blood pressure quickly, although sometimes you may need to sit or lie down while recovering. Postprandial hypotension is a type of orthostatic hypotension that occurs after meals.

In neurally mediated (abnormal signaling of the brain and nerves) hypotension, your blood pressure decreases after extended periods of standing. It may be accompanied by dizziness, faintness, and nausea. This type of low blood pressure is most common in children and young adults and typically resolves over time.

Low blood pressure linked to shock is a serious condition that interferes with blood flow to your vital organs. The drop in blood pressure is more severe than what is seen in orthostatic hypotension or neurally mediated hypotension. Shock can be due to significant blood loss, severe allergic reactions, serious infections, large burns, and poisoning.

Low blood pressure linked to shock is a serious, life-threatening situation. Seek immediate medical care (call 911) for serious symptoms, such as decreased level of consciousness or fainting, chest pain, rapid heart rate, irregular heart rhythm, shortness of breath or lack of breathing, sudden swelling of the face or tongue, dizziness or lightheadedness that does not resolve with sitting or lying down, high fever (higher than 101 degrees Fahrenheit), decreased or absent urine output, or profuse sweating.

If your low blood pressure symptoms are persistent or cause you concern, seek prompt medical care. Prompt medical care is also warranted for prolonged vomiting or diarrhea, increased urinary frequency or urgency, burning with urination, coughing up sputum, or the inability to eat or drink.

SYMPTOMS

What other symptoms might occur with low blood pressure?

Low blood pressure may accompany other symptoms that vary depending on the underlying disease, disorder or condition. Symptoms that frequently affect the cardiovascular system may also involve other body systems.... Read more about low blood pressuresymptoms

CAUSES

What causes low blood pressure?

Low blood pressure can be caused by sudden changes of position (orthostatic hypotension), blood volume redistribution in response to eating (postprandial hypotension), abnormal brain signaling (neurally mediated hypotension), and conditions that cause shock. Medications, heart disease, pregnancy, bedrest, malnutrition, and other health conditions can also contribute to low blood pressure.... Read more about low blood pressurecauses

Medical Reviewer: All content has been reviewed by board-certified physicians under the direction of Rich Klasco, M.D., FACEP. Last Annual Review Date: May 2, 2011 Copyright: © Copyright 2011 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Heart, Blood and Circulation