Hypotension, or low blood pressure, is a condition in which blood flow through the arteries is abnormally low. Blood pressure is measured by two numbers: the systolic (top) number, which measures the pressure when your heart contracts and pumps blood through your body, and the diastolic (bottom) number, which measures the pressure when your heart relaxes between beats. A normal blood pressure reading is 120/80 mmHg.
Hypotension can be dangerous because it means that not enough oxygen-rich blood is reaching your organs and tissues. This can cause dizziness, lightheadedness, fainting, and even shock. If you have hypotension, it's important to see a doctor so that the cause can be identified and treated.