Low blood pressure, also known as hypotension, is a condition in which the blood pressure is lower than normal. Normal blood pressure is considered to be between 120/80 mmHg and 140/90 mmHg. Blood pressure is measured in millimeters of mercury (mmHg) and is recorded as two numbers: the systolic blood pressure (the higher number) and the diastolic blood pressure (the lower number). Systolic blood pressure is the pressure in the arteries when the heart beats, and diastolic blood pressure is the pressure in the arteries when the heart rests between beats. Low blood pressure is diagnosed when the systolic blood pressure is below 90 mmHg or the diastolic blood pressure is below 60 mmHg.
Low blood pressure can cause a variety of symptoms, including dizziness, lightheadedness, fainting, fatigue, and nausea. In severe cases, low blood pressure can lead to shock, which can be life-threatening. There are a number of things that can cause low blood pressure, including dehydration, blood loss, certain medications, and medical conditions such as heart failure and sepsis.