Follow your doctor's instructions when taking this medication orally, usually once a day, with or without food. The prescribed dosage depends on your medical condition and how your body responds to the treatment.Benicar, an ARB medication, contains olmesartan which works by preventing blood vessels from constricting. This results in improved blood flow and reduced blood pressure levels. Benicar is prescribed for the management of hypertension in adults as well as children who are aged six years or above.