Low Blood Pressure

Low blood pressure occurs when blood flows through your blood vessels at lower than normal pressures. The medical term for low blood pressure is hypotension.

Blood pressure is the force of blood pushing against the walls of your
arteries

artery

(ARR-tuh-ree):

A blood vessel that carries blood from the heart to the organs. Most arteries carry oxygenated blood. The pulmonary arteries carry deoxygenated blood away from the heart to the lungs.

as the heart pumps blood. It is usually described as two numbers:
systolic

systolic

(sis-TOL-ik):

The phase of circulation when the heart pumps and the pressure of blood against the vessels is highest.

and
diastolic

diastolic

(DY-uh-stol-ik):

The phase of circulation when the heart fills and the pressure of blood against the vessels is lowest.

. The numbers record blood pressure in millimeters of mercury (mm Hg), with systolic listed above diastolic.

For most adults, a normal blood pressure is usually less than 120/80 mm Hg. Low blood pressure is blood pressure that is lower than 90/60 mm Hg.

Some people have low blood pressure all the time, and it is normal for them. Other people experience a sudden drop in blood pressure or have low blood pressure that may be linked to a health problem. This can be dangerous, as it could mean your heart, brain, or other vital organs are not getting enough blood flow and you are at risk for a heart attack or stroke.

What causes low blood pressure?

Many systems of the body, including organs, hormones, and nerves, regulate blood pressure. For example, the
autonomic nervous system

autonomic nervous system

(AW-toh-NAH-mik NER-vus SIS-tem):

The part of the nervous system that controls muscles of internal organs, such as the heart, blood vessels, lungs, and stomach.

sends the “fight-or-flight” signal that, depending on the situation, tells the heart and other systems in the body to increase or decrease blood pressure. Problems with the autonomic nervous system, such as in Parkinson’s disease, can cause low blood pressure.

Other causes of low blood pressure include:

• Blood loss from an injury that causes a sudden drop in blood pressure
• Dehydration
• Diabetes
• Heart problems such as arrhythmias (irregular heartbeat)
• Medicines to treat high blood pressure, depression, or Parkinson’s
• Pregnancy

Older adults also have a higher risk for symptoms of low blood pressure, such as falling, fainting, or dizziness upon standing up or after a meal. Older adults are more likely to develop low blood pressure as a side effect of medicines taken to control high blood pressure.

What are the symptoms?

For many people, low blood pressure goes unnoticed. Others may feel symptoms such as:

• Confusion
• Dizziness or lightheadedness
• Fainting
• Feeling tired or weak
• Blurry vision
• Headache
• Neck or back pain
• Nausea
• Heart palpitations, or feelings that your heart is skipping a beat, fluttering, or beating too hard or too fast

What should you do if you have symptoms?

Sitting down may relieve the symptoms. If your blood pressure drops too low, your body’s vital organs do not get enough oxygen and nutrients. When this happens, low blood pressure can lead to
shock

shock

(shok):

A state in which not enough blood flows throughout the body, causing damage to the cells and tissues.

, which requires immediate medical attention. Signs of shock include cold and sweaty skin, rapid breathing, a blue skin tone, or a weak and rapid pulse. Call 9-1-1 if you notice signs of shock in yourself or someone else.

Talk to your doctor about your symptoms. Your doctor will use a blood pressure test to diagnose low blood pressure. Other tests may include blood, urine, or imaging tests and a tilt table test if you faint often.

How is it treated?

You may not need treatment for low blood pressure. Depending on your symptoms, treatment may include drinking more fluids to prevent dehydration, taking medicines to raise your blood pressure, or adjusting medicines that cause low blood pressure.

Your doctor may talk to you about lifestyle changes, including changing what and how you eat and how you sit and stand up. Your doctor may also recommend compression stockings if you stand for long periods.

Learn more about Low Blood Pressure from the U.S. National Library of Medicine.

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