Low blood pressure, also known as hypotension, is generally considered a blood pressure reading lower than 90 millimeters of mercury (mm Hg) for the top number (systolic) and/or lower than 60 mm Hg for the bottom number (diastolic). However, whats considered low blood pressure for one person might be okay for someone else, and most health care providers consider blood pressure to be too low only if it causes symptoms. Symptoms of low blood pressure can include dizziness, lightheadedness, nausea, fainting, fatigue, confusion, neck or back pain, headache, blurred vision, heart palpitations, cold and clammy skin, rapid and shallow breathing, and depression. If you have symptoms of extreme low blood pressure or shock, seek emergency medical help. Its important to find out whats causing low blood pressure so that it can be treated, if necessary.