"Contained within alcohol products are toxins called cogners that cause the ill effects known as a hangover. These toxins are positively charged molecules that invade the cellular level of your body disrupting the acid/alkaline balance of the body. This imbalance can cause the body to fight back. That fight presents itself as vomiting upset stomach, headache, sweats, chills and more."
My anti-hangover regimen consists of two aspirin, two antacids, and two 16 oz. glasses of water just before bed. Then, in the morning, I eat a nice complete breakfast.
Of course, this all can be avoided if you stick to high quality single malt liquor...