Hypertension can be classified as either essential or secondary. Essential hypertension indicates that no specific medical cause can be found to explain a patient's condition. Secondary hypertension indicates that the high blood pressure is a result of (i.e. secondary to) another condition, such as kidney disease or certain tumors (especially of the adrenal gland).

Mild hypertension is usually treated by diet, exercise and improved physical fitness. A diet rich in fruits and vegetables and low fat or fat-free dairy foods and moderate or low in sodium lowers blood pressure in people with hypertension. This diet is known as the DASH diet (Dietary Approaches to Stop Hypertension), and is based on National Institutes of Health sponsored research. Regular mild exercise improves blood flow, and helps to lower blood pressure. In addition, fruits, vegetables, and nuts have the added benefit of increasing dietary potassium, which offsets the effect of sodium and acts on the kidney to decrease blood pressure. Dietary sodium (salt) may worsen hypertension in some people and reducing salt intake decreases blood pressure in a third of people. Many people choose to use a salt substitute to reduce their salt intake.

Doctors recommend weight loss and regular exercise as the first steps in treating mild to moderate hypertension. These steps are highly effective in reducing blood pressure, although most patients with moderate or severe hypertension end up requiring indefinite drug therapy to bring their blood pressure down to a safe level. Reduction of environmental stressors such as high sound levels and over-illumination can be an additional method of ameliorating hypertension. Biofeedback is also used particularly device guided paced breathing. Discontinuing smoking does not directly reduce blood pressure, but is very important for people with hypertension because it reduces the risk of many dangerous outcomes of hypertension, such as stroke and heart attack. An increase in daily calcium intake has also been shown to be highly effective in reducing blood pressure.