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What Causes Low Blood Presure?

Blood pressure is the force of circulating blood against the walls of blood vessels. This pressure is produced mainly by the heart muscle's contractions. Low blood pressure is called hypotension and is any pressure reading that is below an individual's normal reading. Due to variations in age, activity, medications and possible medical conditions, low blood pressure is relative to each individual and has no set number or reading. A pressure of 120/80 is considered normal in most people.

  1. Blood Loss

    • Blood loss is one of the main common causes of low blood pressure. Loss of blood can occur from injury or trauma, complications from surgery or from gastrointestinal problems like ulcers, diverticulitis and tumors. Rarely, bleeding can be severe and fast acting enough that it may cause shock or even death. This type of serious bleeding stems from abnormalities such as aortic aneurysms, which is the localized dilation or widening of blood vessels.

    Heart Disease

    • The many effects of heart disease are considerable factors for low blood pressure. A weak heart muscle caused by a heart attack or infection of the heart can reduce blood flow which in turn lowers blood pressure. Additional heart disease problems that result in low blood pressure include tachycardia (abnormally rapid heart rate), bradycardia (slow heart rate), pulmonary embolism (a blood clot in the heart and lungs) and pericarditis (inflammation of the sac that surrounds the heart).

    Medications

    • Sometimes, medications prescribed to treat separate conditions can cause low blood pressure. For instance, calcium channel blockers that are used in the treatment of angina and abnormal heart rhythms can reduce the heart's contractions and lead to low blood pressure. Other drugs that can lower blood pressure include amitriptyline (Elavil) for depression, sildenafil (Viagra) for erectile dysfunction (when used in combination with nitroglycerine) and diuretics (water pills) like furosemide (Lasix).

    Medical Conditions

    • Occasionally, other medical conditions can cause a temporary lowering of blood pressure as a side effect. A vasovagal reaction, which occurs when the vagus nerve becomes overactive during times of emotional overload or gastrointestinal upset, releases hormones that may cause the heart rate to decrease and blood vessels to widen. Conditions such as septicemia (serious infection), adrenal insufficiency (damaged adrenal glands) and anaphylactic shock (severe allergic reaction) can also lead to lowered blood pressure.

    Temporary Situations

    • There are occasions when people in excellent health experience random bouts of low blood pressure due to temporary situations or illnesses. Examples of these situations include pregnancy, which uses one blood supply for both mother and infant, and serious dehydration brought about by diarrhea, vomiting or excessive sweating, resulting in a decrease of blood volume due to lack of hydration. In people with these temporary conditions, signs to look for include dizziness, lightheadedness and fainting.

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