How low is too low for blood pressure?

If you faint . . .: Low blood pressure is relative. In fact, blood pressure is just a number so that lowering a number isn't the goal as much as decreasing your risk of death, stroke, kidney failure, heart failure, etc. That's what you want - the clinical outcome benefit, not just a number. Younger thinner women can run lower BP then older heavier men. But too low can be defined as feeling faint, weak or passing out.

Low bp: If you're having weakness, dizziness, lightheadedness and your BP is less than 90mmHg systolic it is likely too low. Above 90mmHg those symptoms are less likely to be BP related.