Blood pressure is the force against which blood flows in the blood vessels of the body providing blood along with necessary oxygen and nutrients to various parts of the body.

For good functioning of the body it is important that the blood pressure remains within normal limits. Whereas   hypertension, i.e. high blood pressure(>140/90 mm.Hg), is harmful and causes many complications in the body, a low blood pressure i.e. hypotension, (<90/60 mm.Hg) is equally harmful.

With a mild reduction   in blood pressure, one feels giddy. He   has a sensation of falling down and has darkness before the eyes. When the blood pressure falls further, he feels unable to stand up straight. Severe fall of blood pressure results in shock, which is a state without pulse or blood pressure. If not corrected immediately, this state can be fatal due to lack of perfusion to vital parts of the body like brain and heart.  Any other   symptoms   occur due to the condition causing low blood pressure.

Low blood pressure can be acute in onset as occurs due to loss of fluid and electrolytes from the body as in diarrhea and or vomiting. Trauma with blood   loss whether from external or internal injuries can also lead to a low blood pressure. The   extent of fall in blood pressure depends on the quantity of blood or fluid lost. Sepsis due to severe infection is also a cause for low blood pressure.

Chronic hypotension   can occur due to damage to the   heart valves as in mitral   stenosis. Here due to narrowing of the heart valve, blood is not pumped out in sufficient quantity to the body parts. Therefore the blood pressure remains low and one feels giddy. Heart failure also causes low blood pressure.

Severe anemia is known to impair perfusion of heart and result in low blood pressure.

Chronic infections like tuberculosis and HIV are also accompanied at times by low blood pressure.

Drugs for hypertension can   induce a less than normal blood pressure. Therefore it is important to monitor the blood pressure of an individual who takes antihypertensive medication regularly. If the blood pressure falls below normal, dose of the drug   has to be reduced proportionately. Similarly diuretics (medicines used to mobilize extra salt and water from the body) can also cause a low blood pressure.

Varicose veins (dilatation of the veins of the lower limb), is yet another condition which leads to low blood pressure. In this, there is insufficient return of blood to the heart due to the dilated veins. This affects filling of the heart and its output leading to low blood pressure.

Some people have a tendency for low blood pressure with change in position, which is known as orthostatic hypotension. When they stand up from a lying or sitting position, blood pressure tends to fall.

In the same way, some individuals develop low blood pressure when they stand in the same position continuously for long time. This occurs due to pooling of blood in the lower limbs. 

Acute   hypotension as occurs with trauma or gastroenteritis necessitates urgent resuscitation to prevent shock. This includes perfusion with fluids containing saline and electrolytes.

Elevation of the legs is very useful as a first aid measure to help in improving the return of blood to the heart and hence improving the blood pressure. Even those with a chronic blood pressure can benefit by lying down for an hour or so with legs elevated.

Those having varicose veins should use elastic stockings or a crepe bandage to keep the veins compressed. This augments the amount of blood returning to the heart and thus prevents hypotension.

People having orthostatic hypotension should avoid sudden change of position to avoid low blood pressure. Moving toes while standing straight for a long time, helps in avoiding hypotension in those who are prone to it.

Correction of the   disease process causing low blood pressure cures the low blood pressure also.

Eating meals at regular times helps to keep the body healthy and also avoid a low blood pressure.

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