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Low blood pressure

Hypotension; Blood pressure - low; Postprandial hypotension; Orthostatic hypotension; Neurally mediated hypotension; NMH

Low blood pressure occurs when blood pressure is much lower than normal. This means the heart, brain, and other parts of the body do not get enough blood. Normal blood pressure is mostly between 90/60 mmHg and 120/80 mmHg.

The medical name for low blood pressure is hypotension.

Causes

Blood pressure varies from one person to another. A drop as little as 20 mmHg, can cause problems for some people. There are different types and causes of low blood pressure.

Severe hypotension can be caused by sudden loss of blood (shock), severe infection, heart attack, or severe allergic reaction (anaphylaxis).

Orthostatic hypotension is caused by a sudden change in body position. This occurs most often 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 Parkinson disease.

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 high blood pressure and coronary heart disease
  • Medicines used for surgery
  • Painkillers

Other causes of low blood pressure include:

Symptoms

Symptoms of low blood pressure may include:

  • Blurry vision
  • Confusion
  • Dizziness
  • Fainting (syncope)
  • Lightheadedness
  • Nausea or vomiting
  • Sleepiness
  • Weakness

Exams and Tests

The health care provider will examine you to determine the cause of your low blood pressure. Your vital signs (temperature, pulse, rate of breathing, and blood pressure) will be checked frequently. You may need to stay in the hospital for a while.

The 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:

Treatment

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 a drop in 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 through a needle (IV)
  • 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 drug. Do not stop taking any medicines before talking to your provider.
  • Your provider may suggest drinking more fluids to treat dehydration.
  • Wearing compression stockings 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.

Outlook (Prognosis)

Low blood pressure can usually be treated with success.

Possible Complications

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 starves 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.

When to Contact a Medical Professional

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 CPR.

Call your provider right away if you have any of the following symptoms:

Prevention

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
Open References

References

Calkins HG, Zipes DP. Hypotension and syncope. In: Zipes DP, Libby P, Bonow RO, Mann DL, Tomaselli GF, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 11th ed. Philadelphia, PA: Elsevier; 2019:chap 43.

Schrigern DL. Approach to the patient with abnormal vital signs. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 7.

  • Tracking your blood pressure at home

    Tracking your blood pressure at home

    Animation

    •  

    Tracking your blood pressure at home - Animation

    Following your blood pressure at home has gotten a lot easier in the last few years. I'm Dr. Alan Greene. I'd like to share with you a little bit about that. Not too long ago when you wanted to follow your blood pressure at home, you had to have the old fashion sphygmomometer, and the device was a complex as that word sounds. You had to pump something up, and put a stethoscope in your ears, and fumble all these different tubes and even so wouldn't get a very accurate reading. Now, there are simple, high quality, digital blood pressure cuffs. They're easy to use at home. They're built so they snap on the arm very easily, just press a single button, and the chip inside does the work for you. It blows it up, it gives you the reading, and some of the newer models even connect it to your PC and track the readings for you. Now, how accurate are they? They're really pretty good. I wouldn't trust a single reading that much if you get one that's high or low. I wouldn't be either reassured or panicked. But, I would trust the pattern of readings. So, if you have one that tracks it for you, that's great, if not, just write them down what date and time you took it and see what the pattern is over time. If there's anything of concern, be sure to report it to your physician.

  • Tracking your blood pressure at home

    Tracking your blood pressure at home

    Animation

    •  

    Tracking your blood pressure at home - Animation

    Following your blood pressure at home has gotten a lot easier in the last few years. I'm Dr. Alan Greene. I'd like to share with you a little bit about that. Not too long ago when you wanted to follow your blood pressure at home, you had to have the old fashion sphygmomometer, and the device was a complex as that word sounds. You had to pump something up, and put a stethoscope in your ears, and fumble all these different tubes and even so wouldn't get a very accurate reading. Now, there are simple, high quality, digital blood pressure cuffs. They're easy to use at home. They're built so they snap on the arm very easily, just press a single button, and the chip inside does the work for you. It blows it up, it gives you the reading, and some of the newer models even connect it to your PC and track the readings for you. Now, how accurate are they? They're really pretty good. I wouldn't trust a single reading that much if you get one that's high or low. I wouldn't be either reassured or panicked. But, I would trust the pattern of readings. So, if you have one that tracks it for you, that's great, if not, just write them down what date and time you took it and see what the pattern is over time. If there's anything of concern, be sure to report it to your physician.

    A Closer Look

     

    Self Care

     

    Tests for Low blood pressure

     
     

    Review Date: 1/16/2021

    Reviewed By: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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