What causes low blood pressure?Low blood pressure can result from conditions that do not begin in the nervous system, conditions of the nervous system, and drugs. The most important cause of low blood pressure is faulty nutrition. It makes the tissues forming the walls of the blood vessels over relaxed, and flabby or stretched. This results in less supply of oxygen and nutrients to the tissues. Malnutrition can result from a diet deficient in calories, proteins, vitamin C, or almost any one of he B vitamins.
Conditions that are not nervous system illness which can cause low blood pressure include bleeding, infections, dehydration, heart disease, adrenal insufficiency, pregnancy, prolonged bed rest, poisoning, toxic shock syndrome, and blood transfusion reactions.
Conditions of the nervous system which can lead to low blood pressure include changing position from lying to more vertical (postural hypotension), stroke, shock, lightheadedness after urinating or defecating, fright, Shy-Drager syndrome, Parkinson's disease, and neuropathy.
Drugs which can cause low blood pressure include blood pressure drugs, diuretics (water pills), heart medications (especially calcium antagonists-nifedipine/Procardia, beta blockers-propranolol/Inderal and others), depression medications (such as amitriptylene/Elavil), and alcohol. Certain medications and drugs have the effect of substantially lowering blood pressure. In this case, the medication may work too well and make the blood pressure too low. Many other medications, such as the sedative diazepam or amitriptyline, which is used to treat depression, can cause low blood pressure in some people.