Exact high blood pressure causes are not clear exactly what causes hypertension. But there are several things that can increase the risk of hypertension. Common high blood pressure causes are smoking, obesity, stress, older age and use of too much salt etc. Lack of physical activity is another cause of hypertension. If you consume too much alcohol then it also becomes the reason for hypertension. Some people may have high blood pressure that is linked to another medical condition, such as kidney problems. For these people treating the medical problem may lower their blood pressure back to normal.