Alcohol is a diuretic. A diuretic forces the water out of the body, making it more difficult to rehydrate. Skin cells love water, and alcohol removes the water quite rapidly, leaving the skin dehydrated and dull.
Alcohol has an inflammatory effect on the body. When drank, it causes the insides to become inflamed and will quickly show up on the skin in the form of redness, breakouts and puffiness.
The sugar in alcohol can quite literally crystallise the skin cells, leading to less plump, supple cells, duller complexion and breakouts.
Alcohol can deplete healthy levels of the important bacteria in the stomach, which is important in managing inflammatory skin conditions such as eczema.
Sugar in alcohol can cause elevated insulin. Which can have a negative affect on thyroid and sex hormones. Hormonal imbalance can cause skin problems.
24 hours after one night of excessive drinking (three drinks or more) the skin can appear dull, slack and lined.
Some people might see benefits after 3 days of abstaining from alcohol, which gives the liver time to excrete alcohol, sugars and its other ingredients.