The main causes of low blood pressure are
Low blood volume: Low blood volume can also lead to low blood pressure. Excessive blood loss from major shock, dehydration, or acute internal bleeding causes hypovolemia, resulting in a severe drop in blood pressure.
Heart problems: low blood pressure, abnormal heart rate, problems with heart valves, heart attacks. The two parties may not meet at your meeting of the parties.
Low blood sugar, and in some cases diabetes