Low blood pressure, or hypotension, can be a serious medical problem, compromising blood flow to the body organs and tissues. Low blood pressure often presents with dizziness or fainting when rising to a standing position, caused by insufficient blood flow to the brain. Most of the conditions and disorders that cause low blood pressure affect both women and men.
Pregnancy may cause low blood pressure. The blood vessels dilate during pregnancy, which often causes a decrease in blood pressure. In the late stages of pregnancy, compression of the large blood vessels in the abdomen by the growing womb can also contribute to low blood pressure. Staying well hydrated and getting up slowly may help reduce dizziness in women with pregnancy-associated hypotension.
Dehydration is a frequent cause of low blood pressure, occurring when water losses exceed fluid intake. Common causes of dehydration include persistent vomiting or diarrhea, high fever and heat exhaustion. Diuretic, or water pill, abuse can also cause dehydration. Replenishing body water with oral or intravenous fluids corrects dehydration-related low blood pressure in most cases. Severe dehydration, such as occurs with heat stroke or burns, can cause a potentially life-threatening condition known as hypovolemic shock. Markedly reduced blood flow can lead to permanent organ damage with hypovolemic shock.
Certain heart conditions may cause low blood pressure. Bradycardia, or an abnormally slow heart rate, commonly causes low blood pressure. Malfunctioning heart valves may also lead to low blood pressure. Many women and men have a low blood pressure during a heart attack and while recovering. Among patients with heart failure, the decreased pumping ability of the heart commonly leads to low blood pressure.
Severe bleeding commonly causes hypotension, which may lead to life-threatening shock. Traumatic injuries with heavy internal or external bleeding can quickly deplete the blood volume, leading to shock. Blood vessel rupture and certain types of gastrointestinal bleeding can also rapidly deplete the circulatory blood supply. Among women, an ectopic pregnancy--where a fertilized egg begins growing outside of the womb--can cause internal bleeding, which may progress to shock. Severe bleeding requires emergency medical treatment to repair the source of the bleeding and replace lost blood.
Many medications can cause low blood pressure. Types of medications that may cause low blood pressure include water pills, beta blockers, angiotensin converting enzyme inhibitors, calcium channel blockers, tricyclic and tetracyclic antidepressants, monoamine oxidase inhibitors, certain psychiatric medications, barbiturates and narcotic pain relievers. Because alcohol also causes a decrease in blood pressure, taking one of these medications with alcohol may provoke a profoundly low blood pressure.