Hypertensive crisis, also called hypertensive emergency, happens when blood pressure becomes so high that it is causing immediate danger and needs to be reduced rapidly. A person is said to be in a hypertensive crisis when his or her blood pressure is severely elevated and there are signs or symptoms of damage to the brain, heart, kidneys, or other organs.

Typically, a person in hypertensive crisis has a diastolic blood pressure (the lower number in a blood pressure reading) greater than 120 millimeters of mercury (mm Hg). In comparison, normal diastolic pressure for an adult is less than 79 mm Hg. Diastolic pressure refers to the pressure of blood in the artery when the heart relaxes between beats.

Quick-acting medications can be used to reduce blood pressure during hypertensive crisis.