General: Hypotension (low blood pressure) without symptoms is not generally a cause for concern. Long-term hypotension that does not cause symptoms is rarely serious. In fact, many athletes have low blood pressure and have a decreased risk of developing heart disease.
Hypotension that causes symptoms may be a sign of an underlying health condition. Sometimes, hypotension may even indicate a serious and/or life-threatening problem, such as a widespread infection. Below are some of the most common causes of hypotension.
Allergic reaction (anaphylaxis): A life-threatening allergic reaction, called anaphylaxis, often causes a sudden and dramatic drop in blood pressure. Additional symptoms may include itching, hives, difficulty breathing, swelling of the throat and tongue, stomach cramps, nausea, and diarrhea. This reaction may occur in response to medications, herbs, supplements, foods (such as peanuts), bee stings, or other severe allergies.
Sudden hypotension may occur if a person loses a lot of blood from a serious injury, internal bleeding, or complications during surgery. The severity of hypotension depends on how much blood is lost.
Endocrine problems: Endocrine disorders, also called hormonal disorders, may cause hypotension. Endocrine problems occur when the body releases too many or too few hormones, which are chemicals that help regulate bodily functions. Endocrine problems, such as an underactive thyroid (called hypothyroidism), overactive thyroid (called hyperthyroidism), adrenal insufficiency (called Addison's disease), low blood sugar levels, and in some cases, diabetes, may lead to hypotension.
Dehydration: Dehydration may lead to hypotension. Even mild dehydration may cause symptoms, such as lightheadedness, dizziness, and weakness. Severe dehydration may lead to a life-threatening complication, called hypovolemic shock. This condition occurs when a decreased blood volume in the body causes a sudden drop in blood pressure. As a result, the body's tissues and organs do not receive enough oxygen. If left untreated, hypoyolemic shock may be fatal within a few minutes to hours.
Heart problems: Several heart problems, including an extremely low heart rate (called bradycardia), heart valve problems, heart attack, and heart failure, may lead to hypotension. These conditions prevent the body from circulating enough blood to tissues and organs.
Medications: Many drugs can cause low blood pressure, including diuretics, blood pressure-lowering drugs, heart medications (such as beta blockers or calcium channel blockers), drugs used to treat Parkinson's disease, tricyclic antidepressants, erectile dysfunction drugs (such as Viagra®), narcotics, and alcohol. Other medications (prescription and over-the-counter) may lower blood pressure when they are taken in combination with blood pressure-lowering drugs.
Nutritional deficiencies: People who have low levels of vitamin B-12 and folate may develop anemia, a condition that may cause low blood pressure. People who have eating disorders, such as anorexia or bulimia, have an increased risk of developing nutritional deficiencies that can lead to hypotension.
A woman's blood pressure often decreases during pregnancy. This is because the mother's circulatory system expands quickly during pregnancy. During the first 24 weeks of pregnancy it is common for a woman's systolic blood pressure to drop five to 10 points and for her diastolic pressure to drop 10-15 points.
Septicemia and septic shock:
A severe infection, called septicemia, may lead to hypotension. Septicemia occurs when an infection enters the bloodstream and spreads throughout the body. As the heart works extra hard to pump blood throughout the body, it starts to weaken and blood pressure drops. When blood pressure drops to dangerously low levels, the condition is called septic shock.
General: If a person has symptoms of hypotension, the goal is to determine the underlying cause. A doctor may perform one or more of the following tests to reach a diagnosis.
Blood tests: Blood tests may be performed to determine if an infection is present in the blood. They are also used to detect possible endocrine problems, such as low blood sugar levels, an underactive or overactive thyroid gland, or adrenal insufficiency. Blood tests may also determine if the patient has vitamin B-12 or folate deficiencies and/or anemia.
An echocardiogram may also be performed to detect possible abnormalities in the heart muscle. This test is similar to an ultrasound that is used in pregnant women. A wand-like device (called a transducer) is rubbed on the patient's chest, and sound waves produce images of the heart. This test can detect abnormalities in the heart rhythm or structure. It can also detect possible heart muscle damage caused by heart attacks or heart disease.
Electrocardiogram (ECG, EKG):
An electrocardiogram may be performed to detect abnormalities in the heart's rhythm or structure. It can also detect problems with the supply of blood to the heart muscle. During the procedure, small electrode patches attached to the person's chest, arms, and legs. These electrodes transmit information about the electrical activity of the heart to a monitor.
Stress test: A stress test may also be performed to determine how blood pressure changes when the heart is working harder than normal. This test may make it easier for a doctor to diagnose hypotension. During the test, the patient either exercises (often on a treadmill) or is given medication to make the heart work harder. Small electrodes are placed on the patient's chest to monitor the electrical activity of the heart. The patient's blood pressure may also be monitored. People with hypotension will have lower blood pressure during a stress test than healthy people who undergo a stress test.
Tilt-table test: Patients who have postural hypotension or neutrally mediated hypotension may undergo a tilt-table test. During the test, the patient lies on a table that is tilted to raise the upper part of the body. The patient's blood pressure is measured during the test to determine how the body reacts to changes in position.
Valsalva maneuver: A valsalva maneuver test may be performed to evaluate the functioning of a patient's autonomic nervous system. This test analyzes the patient's heart rate and blood pressure after several cycles of deep breathing. The patient is asked to take a deep breath and force air out through the lips when exhaling. In a healthy person, this action traps blood in the major arteries, preventing it from entering the chest and right atrium. When the person breathes out, the intrathoracic pressure drops and the trapped blood is quickly pumped through the heart. This causes an increase in the heart rate and the blood pressure. Immediately after the valsalva maneuver, the heartbeat starts to slow down. Abnormalities in this response may indicate problems with the person's autonomic nervous system.
signs and symptoms
General: In general, hypotension (low blood pressure) is only considered a problem when symptoms develop. Symptoms may be persistent or they may only occur when a person stands for extended periods of time, stands up after sitting or lying down, or after a person eats. If blood pressure drops suddenly, it is often a sign of a life-threatening medical condition, and the person should immediately be taken to the nearest hospital.
Common symptoms: Common symptoms of hypotension include dizziness, lightheadedness, blurred vision, pale skin, and fatigue. Individuals should be taken to the nearest hospital if they faint or lose consciousness, have difficulty breathing, or experience nausea. These may be signs of a serious medical problem.
Additional symptoms: Depending on the underlying cause, additional symptoms may also be present. For instance, if a severe allergic reaction, called anaphylaxis, is causing symptoms, additional symptoms may include itching, hives, difficulty breathing, swelling of the throat and tongue, stomach cramps, nausea, and diarrhea.