Postural hypotension occurs most frequently in people who are taking drugs to control high blood pressure (hypertension). It can also be related to pregnancy, strong emotions, hardening of the arteries (atherosclerosis), or diabetes. The elderly are particularly affected, especially those who have high blood pressure or autonomic nervous system dysfunction.
Blood pressure is given as a reading of two numbers, such as 110/70. The higher number (systolic) is the pressure when the heart beats. The diastolic, or lower number shows the pressure between the heartbeats, while the relaxed heart is refilling with blood. Normal blood pressure readings are lower than 120/80. The cause of most hypertension is unknown. Occasionally, conditions of the kidney or adrenal gland are the cause of high blood pressure.
The best evidence indicates that high blood pressure does not cause headaches or nosebleeds, except in the case of hypertensive crisis, a medical emergency when blood pressure is 180/120 mm Hg or higher. If your blood pressure is unusually high AND you have headache or nosebleed and are feeling unwell, wait five minutes and retest. If your reading remains at 180/120 mm Hg or higher, call 9-1-1.  
Medications such as calcium channel blockers, beta blockers, and digoxin (Lanoxin) can slow the rate at which the heart contracts. Some elderly people are extremely sensitive to these medications since they are more likely to have diseased hearts and electrical conduction tissues. In some individuals, the heart rate can become dangerously slow even with small doses of these medications.
The veins can expand and narrow. When veins expand, more blood can be stored in the veins and less blood returns to the heart for pumping into the arteries. As a result, the heart pumps less blood, and blood pressure is lower. On the other hand, when veins narrow, less blood is stored in the veins, more blood returns to the heart for pumping into the arteries, and blood pressure is higher.
Moderate or severe bleeding can quickly deplete an individual's body of blood, leading to low blood pressure or orthostatic hypotension. Bleeding can result from trauma, surgical complications, or from gastrointestinal abnormalities such as ulcers, tumors, or diverticulosis. Occasionally, the bleeding may be so severe and rapid (for example, bleeding from a ruptured aortic aneurysm) that it causes shock and death rapidly.
One especially important cause of low blood pressure is orthostatic hypotension, which is sometimes referred to as postural hypotension. This happens when blood pressure drops rapidly during changes in body position—usually when changing from sitting to standing—inducing classic signs that the blood pressure is too low, like dizziness, blurry vision, and fainting.
*Your diet is an important part of blood pressure control. The Dietary Approaches to Stop Hypertension (DASH) eating plan and limiting sodium (salt) help control blood pressure. Ask your doctor to refer you to a dietitian for specific dietary guidelines. More information is available from the National Heart, Lung and Blood Institute at www.nhlbi.nih.gov or the American Heart Association at www.americanheart.org.*
You can have high blood pressure, or hypertension, and still feel just fine. That's because high blood pressure often does not cause signs of illness that you can see or feel. But, high blood pressure, sometimes called "the silent killer," is very common in older people and a major health problem. If high blood pressure isn't controlled with lifestyle changes and medicine, it can lead to stroke, heart disease, eye problems, kidney failure, and other health problems. High blood pressure can also cause shortness of breath during light physical activity or exercise.
"The recommendations are neither a policy nor a prescription for physicians," says Claude Lenfant, MD, director of the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. "Nobody is advocating some sort of cookbook medicine. The physician will have to decide whether this medication or that medication is the best depending on many considerations."
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

The new guidelines note that blood pressure should be measured on a regular basis and encourage people to use home blood pressure monitors. Monitors can range from $40 to $100 on average, but your insurance may cover part or all of the cost. Measure your blood pressure a few times a week and see your doctor if you notice any significant changes. Here are some tips on how to choose and use a monitor.
Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.
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