What causes a Sudden Drop in Blood Pressure?

By  , Expert Content
Jan 17, 2013

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Sudden drop in blood pressure when you get up from lying down or sitting is known as postural hypotension, orthostatic hypotension, or neurally mediated orthostatic hypotension. Postural hypotension occurs due to failure of the autonomic nervous system.
Autonomic nervous system controls involuntary vital functions like heartbeat, blood pressure, and breathing.

When you, stand up from lying down or sitting, some blood pools in your lower limbs. But normally your body compensates for it increasing your heart rate and constricting the blood vessels. If this fails to happen, or occurs slowly, the blood pressure falls and postural hypotension results. Postural hypotension occurs more common in the elderly.


Cause of Postural Hypotension

Postural hypotension, or low blood pressure on standing up suddenly, can occur due to several reasons such as;

  • Dehydration or loss of water from body due to vomiting, diarrhea, or fever
  • Starvation or lack of food,
  • Standing for long period in the heat,
  • Excessive fatigue or tiredness
  • Elderly
  • Certain medications, like drugs to control high blood pressure (hypertension).
  • Dietary and psychological factors, and
  • Severe infection
  • Allergic reaction.
  • Pregnancy
  • Diabetes.
  • Dysfunction of autonomic nervous system

Some people can have hypotension after meals. It probably occurs due to pooling of blood into the vessels of the stomach and intestines.

Medications which can cause Postural Hypotension

Several drugs can cause postural hypotension. Medications that cause postural hypotension can be categorized as;

  • Drugs to treat high blood pressure: These include diuretics, beta-blockers, calcium-channel blockers, and angiotensin-converting enzyme (ACE) inhibitors.
  • Drugs with hypotension as a side effect: These include nitrates, drugs for Parkinson's disease, medications to treat erectile dysfunction, antipsychotics, neuroleptics, anti-anxiety agents, sedative-hypnotics, and tricyclic antidepressants.


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  • Kathy Williams04 Apr 2013

    After having cervical spine surgery I am having problems with a sudden drop in blood pressure. It ranges around 89/52 when it falls while sitting. When I stand up I get dizzy but then the pressure comes up to like 106/59. My doctor told me that I may have autonomic nerve disease. Could you please post some information regarding this disease?

  • Imtiaz Ahmad Pervez09 May 2012

    You have not mentioned Sepsis which is a bacteria that can also cause sudden drop in blood pressure.

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