Hypertension, commonly known as high blood pressure, where the arterial pressure is elevated above the normal range expected in a particular age group. It may be of unknown cause (hyperpiesia) or it may result from kidney disease, narrowing of the renal artery (renal hypertension), endocrine diseases or disease of the arteries (symptomatic hypertension). Complications that may arise from it are atherosclerosis, heart failure, cerebral hemorrhage, and kidney failure, but treatment may prevent their development. Hypertension does not show symptoms until the symptoms of its complications develop. Most cases of hypertension depend upon long-term drug therapy to lower the blood pressure and maintain it low. Most common drugs used in the treatment of hypertension are thiazide diuretics, methyl-dopa, guanethidine and propranolol.