In 90 percent to 95 percent of high blood pressure cases, the American Heart Association says there is no identifiable cause. This type of high blood pressure, called essential hypertension or primary hypertension, tends to develop gradually over many years.

The other 5 percent to 10 percent of high blood pressure cases are caused by an underlying condition. This type of high blood pressure, called secondary hypertension, tends to appear suddenly, and cause higher blood pressure than does primary hypertension. Various conditions can lead to secondary hypertension, including kidney abnormalities, tumors of the adrenal gland, or certain congenital heart defects.

Certain medications – including birth control pills, cold remedies, decongestants, over-the-counter pain relievers and some prescription drugs – may also cause secondary hypertension. Various illicit drugs, including cocaine and amphetamines, also can increase blood pressure.

High blood pressure has many risk factors:

  • Excess weight- The greater your body mass, the more blood you need to supply oxygen and nutrients to your tissues. As the volume of blood circulated through your blood vessels increases, so does the pressure on your artery walls.
  • Inactivity- People who are inactive tend to have higher heart rates. The higher your heart rate, the harder your heart must work with each contraction — and the stronger the force on your arteries. Lack of physical activity also increases the risk of being overweight.
  • Tobacco use- The chemicals in tobacco can damage the lining of your artery walls, which promotes narrowing of the arteries.
  • Sodium intake- Too much sodium in your diet — especially if you have sodium sensitivity — can lead to fluid retention and increased blood pressure.
  • Low potassium intake- Potassium helps balance the amount of sodium in your cells. If you don’t consume or retain enough potassium, you may accumulate too much sodium in your blood.
  • Excessive alcohol- Over time, heavy drinking can damage your heart.
  • Stress- High levels of stress can lead to a temporary but dramatic increase in blood pressure. If you try to relax by eating more, using tobacco, or drinking alcohol, you may only fuel problems with high blood pressure.

Certain chronic conditions may also increase your risk of high blood pressure, including high cholesterol, diabetes, kidney disease and sleep apnea. Sometimes pregnancy contributes to high blood pressure.