When Alcohol is present in the blood stream it covers the blood vessels and artery walls thereby increasing their tension and thereby increasing the blood pressure. Not only alcohol, but also Caffeine, Smoking, and Drugs also cause high blood pressure. An estimated 10% of hypertension cases are caused by alcohol abuse, three alcoholic drinks a day or more, with heavier drinkers having higher pressure. Caffeine causes a temporary increase in blood pressure, which has been thought to be harmless in people with normal blood pressure. Studies are suggesting, however, that regular, heavy coffee drinking (an average of 5 cups per day) can boost blood pressure, and in one study, this was sufficient to increase the risk for heart disease in healthy men. The potential risk of caffeine, however, pale next to the dangers of smoking. One study reported that smokers have blood pressures up to 10 points higher than nonsmokers. Cocaine is known to cause acute episodes of hypertension.