Hypertension, or high blood pressure, is defined as a systolic blood pressure of 140 mm Hg or higher or a diastolic blood pressure of 90 mm Hg or higher. Factors that influence blood pressure include heart rate, sympathetic nervous system activity, vasoconstriction/vasodilation, and fluid volume regulated by the renin-angiotensin and aldosterone systems. Lifestyle modifications such as weight loss, following the DASH diet, reducing sodium intake, limiting alcohol, and regular exercise are first-line treatment recommendations for controlling hypertension before starting drug therapy.