High blood pressure occurs when the pressure within blood vessels is consistently too high. People with an average blood pressure reading of more than 140/90 have high blood pressure. Most people with high blood pressure have what is known as primary or essential hypertension, meaning that the specific cause or causes of their high blood pressure are not known. Other people have secondary high blood pressure or secondary hypertension, in which case the condition is the result of another medical problem or medicine. If left untreated, high blood pressure can lead to serious health problems, such as heart attack and kidney failure. Some risk factors for high blood pressure include obesity, being physically inactive, and consuming too much sodium.