At any stage of hypertension development and other disease emergencies, severe life-threatening blood pressure increases can occur, requiring emergency treatment. Hypertensive crises include hypertensive emergencies and hypertensive urgencies. Hypertensive emergencies refer to severe blood pressure increases within a short time—hours or days—with diastolic pressure greater than 130 mmHg and/or systolic pressure greater than 180 mmHg, accompanied by severe dysfunction or irreversible damage to critical organs and tissues such as the heart, brain, kidneys, retina, and major arteries. Hypertensive urgencies may present as increased blood pressure but without obvious target organ damage.