In physiology and medicine, hypotension is abnormally low blood pressure. This is best understood as a physiologic state, rather than a disease. It is often associated with shock, though not necessarily indicative of it. Hypotension is the opposite of hypertension, which is high blood
pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. If it is lower than normal then it is called low blood pressure or hypotension. Hypotension is generally considered as systolic blood pressure less than 90 millimeters of mercury (mm Hg) or diastolic less than 60 mm Hg.[1][2] However in practice, blood pressure is considered too low only if noticeable symptoms are present
The cardinal symptom of hypotension is lightheadedness or dizziness. If the blood pressure is sufficiently low, fainting and often seizures will occur.
Low blood pressure is sometimes associated with certain symptoms, many of which are related to causes rather than effects of hypotension:
Cause
Low blood pressure[4] causes can be due to hormonal changes, widening of blood vessels, medicine side effects, anemia, heart & endocrine problems. Reduced blood volume, called
hypovolemia, is the most common mechanism producing hypotension. This can result from hemorrhage, or blood loss; insufficient fluid intake, as in starvation; or excessive fluid losses from diarrhea or vomiting. Hypovolemia is often induced by
excessive use of diuretics. Other medications can produce hypotension by different mechanisms.
