Yasmine Ali, MD, is board-certified in cardiology. She is an assistant clinical professor of Medicine at Vanderbilt University School of Medicine and an award-winning physician writer.
Low blood pressure, also known as hypotension, occurs when blood flows through your blood vessels at pressures that are lower than normal. Blood pressure is defined as the force of blood pushing against artery walls as it is pumped by the heart. Low blood pressure is primarily a concern if it produces symptoms such as dizziness, fainting, blurry vision, or fatigue, or if you have a sudden drop in blood pressure.
Maintaining a healthy blood pressure (below 120/80 millimeters of mercury, or mm HG) can protect you from a host of health issues.
But blood pressure that is too low—defined as below 90/60 mm Hg—can prevent your organs from getting adequate amounts of the oxygenated blood they need to function properly. Hypotension is of particular concern for vital organs like the brain.
Low blood pressure can be caused by factors like dehydration or medications, or it can be related to an underlying condition, such as heart problems, hormone issues, pregnancy, or neural conditions. There are three primary types: orthostatic hypotension, neurally mediated hypotension, and severe hypotension related to shock, which is a medical emergency.
If your blood pressure is consistently below 90/60 mm Hg, be sure to talk to your doctor, though it's important to remember that everyone's different. What's normal for you may be considered low for someone else.
Low blood pressure is usually only considered a problem if it's causing symptoms, such as dizziness, blurry vision, feeling faint, or confusion. However, if your blood pressure drops suddenly, it could be related to shock, which can be dangerous and is a medical emergency. Other symptoms of shock include weak pulse, clammy skin, rapid breathing, and loss of consciousness.
In many cases, drinking plenty of water, increasing your salt intake, avoiding alcohol, and wearing compression stockings can help rebalance your blood pressure. You may also need to avoid standing for extended periods of time, or trying not to change positions (like going from sitting to standing) too quickly. In other cases, medication may be warranted to raise your blood pressure to more stable levels.
Generally speaking, low blood pressure is only problematic if it occurs suddenly or when it's a result of an underlying disease or condition. If you're concerned about your blood pressure, be sure to talk to your doctor.
The force of blood that pushes against artery walls every time the heart beats. Blood pressure is often measured alongside the vital signs (temperature, pulse rate, respiration rate) and is used to detect or monitor medical issues. Readings contain two numbers: systolic pressure and diastolic pressure.
Diastolic pressure is the lower/bottom number in your blood pressure reading. It's defined as the pressure within the arteries between heartbeats, when the heart is at rest. Diastolic hypotension may be seen with dehydration or abnormal bleeding.
A noninvasive diagnostic test that involves electrodes placed on the chest to record and analyze the heart's rhythm, and look for potential problems in blood and oxygen flow to the heart muscle.
The medical term for low blood pressure. The prefix "hypo" means low. Hypotension is the opposite of hypertension, or high blood pressure.
A medical emergency that occurs when blood flow to your organs and tissues becomes severely diminished. There are several causes of shock, including traumatic blood loss and sudden heart failure. Often, the first noticeable symptom is loss of consciousness, and immediate medical intervention is required to prevent the condition from progressing quickly.
Blood pressure is divided into two measurements: systolic and diastolic. Systolic pressure is the pressure exerted when blood is ejected into arteries from the heart (when the heart contracts). It's the higher/top number in your blood pressure reading. Systolic hypotension may be seen with dehydration, major bleeding, or if the heart becomes too weak to efficiently pump blood.
A noninvasive procedure that monitors your blood pressure and other vital signs while you change positions from lying down to standing. As part of the test, you'll be strapped to a table that rotates 70 degrees from lying down flat to standing position. It's often used to determine the cause of fainting (syncope) when other causes have been ruled out.
National Institutes of Health: National Heart, Lung, and Blood Institute. Low blood pressure.
American Heart Association. Low blood pressure: when low is too low. Updated October 31, 2016.