Blood pressure below normal is clinically diagnosed as hypotension. Normal blood pressure ranges from 90 to 140 mm Hg systolic and 60 to 90 mm Hg diastolic. If the systolic pressure is below 90 mm Hg and the diastolic pressure is below 60 mm Hg, it is clinically diagnosed as hypotension. Symptoms of hypotension often include fatigue, dizziness, palpitations, shortness of breath, and darkening before the eyes. Mild hypotension may not present any clinical symptoms, while severe hypotension requires treatment based on clinical symptoms and the underlying disease to correct it.