High blood pressure (hypertension) occurs when your heart pumps blood at a rate that puts unusually high levels of pressure on your arteries. It can be caused by several factors but if the cause is unknown then it is referred to as primary high blood pressure, or primary hypertension. Primary high blood pressure can be deadly, leading to several health complications including heart attacks and strokes. Typically, it doesn't cause any symptoms which means it's important to have your blood pressure checked by your doctor at least a couple times a year. If you are diagnosed with primary high blood pressure there are several steps you can take to lower it.