According to the American Heart Association, effects or symptoms of low blood pressure can include dizziness or lightheadedness; fainting; lack of concentration; blurred vision; dehydration; nausea; cold, clammy skin; shallow, rapid breathing; fatigue and depression. In general, low blood pressure is not cause for concern unless it leads to symptoms. Low blood pressure, however, can be a sign of an underlying abnormality if the individual's blood pressure is usually higher.
The American Heart Association further states that low blood pressure can be caused by a myriad of issues, such as prolonged bed rest or nutritional deficiencies that result in anemia. A decrease in total blood volume can be responsible and results from major trauma, severe internal bleeding or dehydration. Low blood pressure resulting from bradycardia, defective heart valves, heart attacks or heart failure occurs when the heart is physically unable to circulate enough blood for the body. Endocrine and hormonal problems, such as hypothyroidism, low blood sugar, Addison's disease and diabetes, can negatively affect blood pressure. Allergic reaction and severe infection or septic shock are other causes of low blood pressure.
Certain medications are also known to cause low blood pressure, according to the American Heart Association. These include diuretics and drugs that treat hypertension, heart medications, drugs for Parkinson's disease, tricyclic antidepressants, erectile dysfunction drugs and alcohol.