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.
Postural hypotension, or low blood pressure on standing up suddenly, can occur due to several reasons such as;
[Read: Causes of Hypotension]
Some people can have hypotension after meals. It probably occurs due to pooling of blood into the vessels of the stomach and intestines.
Several drugs can cause postural hypotension. Medications that cause postural hypotension can be categorized as;
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