Normal blood pressure is 120/80 mm hg where 120 is the systolic pressure and 80 is the diastolic pressure. Low blood pressure is an abnormal condition where a person's blood pressure is much lower than usual, which can cause symptoms such as dizziness or lightheadedness. When the blood pressure is too low, there is inadequate blood flow to the heart, brain, and other vital organs. A blood pressure level that is borderline low for one person may be normal for another. The most important factor is how the blood pressure changes from the normal condition. Most normal blood pressures fall in the range of 90/60 mm Hg to 130/80 mm Hg, but a significant change, even as little as 20 mm Hg, can cause problems for some people. What are the symptoms of low BP? Symptoms of low BP may include: * Tiredness * General weakness * Light-headedness and fainting * Blurred vision * Dizziness * Palpitations * Confusion * Nausea * Temporary loss of consciousness. What are the causes of low blood pressure? Low blood pressure may be caused by drugs such as the following * Medications used for surgery * Anti-anxiety agents * Treatment for high blood pressure * Diuretics * Heart medicines * Some antidepressants * Narcotic analgesics * Alcohol Other causes of low blood pressure include the following: * Dehydration * Heart failure * Heart attack * Changes in heart rhythm (arrhythmias) * Fainting * Anaphylaxis (a life-threatening allergic response) * Shock (from severe infection, stroke, anaphylaxis, major trauma, or heart attack) * Advanced diabetes Another common type of low blood pressure is orthostatic hypotension, which results from a sudden change in body position, usually from lying down to an upright position.