What is a healthy blood pressure?
WebMD states that blood pressure readings ranging from 120 over 80 to 139 over 89 indicate prehypertension. Readings higher than 140 over 90 indicate high blood pressure. According to the American Heart Association, blood pressure readings greater than 180 over 110 are extremely dangerous and represent a hypertension crisis, which is a medical emergency.
Sources: heart.org, webmd.com, mayoclinic.org