Low blood pressure occurs when blood pressure is below normal. This means the heart, brain, and other parts of the body may not get enough blood. In adults, the normal blood pressure is between 90/60 mmHg and 120/80 mmHg.
The medical word for low blood pressure is hypotension.
Blood pressure varies from one person to another and also over time for any given person. A drop of as little as 20 mmHg can cause problems for some people. There are different types and causes of low blood pressure.
Severe hypotension (shock) can be caused by sudden loss of blood (
), severe infection,
, or severe allergic reaction (
).
Orthostatic hypotension means your blood pressure drops when you shift from lying down to standing. This type of low blood pressure usually lasts only a few seconds or minutes. If this type of low blood pressure occurs after eating, it is called postprandial orthostatic hypotension. This type most often affects older adults, those with high blood pressure, and people with
.
Neurally mediated hypotension (NMH) most often affects young adults and children. It can occur when a person has been standing for a long time. Children usually outgrow this type of hypotension.
Certain medicines and substances can lead to low blood pressure, including:
Alcohol
Anti-anxiety medicines
Certain antidepressants
Diuretics
Heart medicines, including those used to treat
and
Medicines used for surgery
Painkillers
Other causes of low blood pressure include:
or other disorders
Changes in heart rhythm (
)
Not drinking enough fluids (
)
Your health care provider will examine you to determine the cause of your low blood pressure. Your vital signs (temperature,
, rate of breathing, and blood pressure) will be checked frequently. You may need to stay in the hospital for a while.
Your provider will ask questions, including:
What is your normal blood pressure?
What medicines do you take?
Have you been eating and drinking normally?
Have you had any recent illness, accident, or injury?
What other symptoms do you have?
Did you faint or become less alert?
Do you feel dizzy or lightheaded when standing or sitting after lying down?
The following tests may be done:
l
to check for infection
Complete blood count (
), including
Electrocardiogram (
)
Lower than normal blood pressure in a healthy person that does not cause any symptoms often does not need treatment. Otherwise, treatment depends on the cause of your low blood pressure and your symptoms.
When you have symptoms from low blood pressure, sit or lie down right away. Then raise your feet above heart level.
Severe hypotension caused by shock is a medical emergency. You may be given:
Blood or other fluids through a needle (
)
Medicines to increase blood pressure and improve heart strength
Other medicines, such as antibiotics
Treatments for low blood pressure after standing up too quickly include:
If medicines are the cause, your provider may change the dosage or switch you to a different medicine. Do not stop taking any medicines before talking to your provider.
Your provider may suggest drinking more fluids to treat dehydration.
Wearing
can help keep blood from collecting in the legs. This keeps more blood in the upper body.
People with NMH should avoid triggers, such as standing for a long period of time. Other treatments include drinking fluids and increasing salt in your diet. Talk to your provider before trying these measures. In severe cases, medicines may be prescribed.
Low blood pressure can usually be treated with success.
Falls due to low blood pressure in older adults can lead to a broken hip or spine fracture. These injuries can reduce a person's health and ability to move about.
Sudden severe drops in your blood pressure starve your body of oxygen. This can lead to damage of the heart, brain, and other organs. This type of low blood pressure can be life threatening if not treated right away.
If low blood pressure causes a person to pass out (become unconscious), seek treatment right away. Or call 911 or the local emergency number. If the person is not breathing or has no pulse, begin
.
Call your provider right away if you have any of the following symptoms:
Black or maroon stools
Dizziness, lightheadedness
Fainting
Fever higher than 101°F (38.3°C)
Your provider may recommend certain steps to prevent or reduce your symptoms including:
Drinking more fluids
Getting up slowly after sitting or lying down
Not drinking alcohol
Not standing for a long time (if you have NMH)
Using compression stockings so blood does not collect in the legs
Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH
Calkins H, Everett TH, Chen P-S. Hypotension and syncope. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 71.
Schrigern DL. Approach to the patient with abnormal vital signs. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 7.
Updated by: Linda J. Vorvick, MD, Clinical Professor Emeritus, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.