Alcohol is a well-known independent risk factor for cardiovascular diseases. Though Low amount of alcohol is beneficial for the heart and blood vessels, drinking large amount of alcohol can result in raised blood pressure. Excessive alcohol increases the risk of many other cardiovascular events and not just hypertension.
Mechanisms by which alcohol causes hypertension have not been fully elucidated and is likely to be due to multiple mechanisms like increased activity of sympathetic nervous system, increase cortisol levels, damage to the baroreceptors (blood pressure sensors) and numerous others. The beneficial effects of the small amounts of alcohol on cardiovascular system are prevention of atherosclerosis and decreased risk of ischemic heart diseases (by increasing HDL cholesterol and inhibiting thrombus formation). Heavy intake can cause other diseases also, like arrhythmias, heart failure and hemorrhagic stroke. Alcohol can also cause low blood pressure. Drinking large amounts of alcohol for many years can damage peripheral nerves, thus resulting in autonomic neuropathy. Alcohol can also directly damage heart muscle resulting in alcoholic cardiomyopathy. Both of these conditions can result in low blood pressure.
Cutting down on alcohol is an important non-pharmacological approach to treating high blood pressure. Each drink per day reduction lowers blood pressure by about 1 mm Hg. Since a small amount of alcohol has numerous beneficial effects, complete abstinence is not yet recommended. Assuming one drink has ~14 g of alcohol, according to current recommendations, men should not drink more than 2 drinks per day and women should not drink more than 1 drink per day. The beneficial effects of this low amount of alcohol intake are lost if daily intake amount increases above the recommended limit or with binge drinking episodes.