Alcohol dilates the blood vessels.
Large amounts of alcohol, consumed over a large period of time, interrupts and sickens the liver. While the liver is trying to recoop, it isn't filtering the blood as well as it should be. If the liver is not functioning properly, bacteria and impurities will float around in the blood, causing many other organs to suffer via enlarged blood vessels.
Your skin is usually the first sign of liver malfunction, as seen in a condition called :jaundice", which turns the skin and whites of the eyes yellow. Alcohol is a diuretic which means it draws water out of your system. Loss of water, dehydration, causes dry skin (and a hangover).
If you are a heavy drinker alcohol could cause premature aging and a number of other things.