Though generally regarded as a good thing, a person’s blood pressure can be too low and potentially harmful. There may be no symptoms associated with low blood pressure, and, in certain cases, it may actually be desirable. When blood pressure drops below 90/60, however, it indicates that there may not be enough blood flowing to the heart, brain, kidneys, and other major organs.
Causes may include heart disease, dehydration, gastrointestinal bleeding, and the use or allergic reaction to certain medications. Most common with the elderly, sudden drops in blood pressure may lead to symptoms like fatigue, anxiety, depression, or dizziness—especially upon making a sudden change in body movement.
In rare cases, treatment is required, usually in the form of medication that helps alter blood pressure receptors or constrict arteries to reduce the likelihood of sudden or frequent drops in blood pressure
Article source: American Association for the Advancement of Science