low blood pressure signals an underlying problem, especially when it drops suddenly or is accompanied by signs and symptoms such as:
Dizziness or lightheadedness
Fainting (syncope)
Blurred vision
Nausea
Fatigue
Lack of concentrationBlood pressure is a measurement of the pressure in your arteries during the active and resting phases of each heartbeat.
Systolic pressure. The top number in a blood pressure reading is the amount of pressure your heart generates when pumping blood through your arteries to the rest of your body.
Diastolic pressure. The bottom number in a blood pressure reading refers to the amount of pressure in your arteries when your heart is at rest between beats.