Those margaritas don’t look as good on your skin as they did in the glass. If you’ve ever had cotton mouth in the morning after a night of drinks, you know alcohol dehydrates you. This makes a big impact on your skin, which is 63% water. Even if you drink a big glass of water, it will hydrate all your other organs before your skin. When you don’t get enough, your skin looks and feels dry, and can’t defend itself against wrinkles.