When your body metabolizes alcohol, it creates a substance called acetaldehyde, which is then broken down by enzymes in your body. There's only one sure way to avoid a hangover, and you probably know what it is: Don't drink alcohol. If you do drink, don't drink in excess and stick with one type of alcohol for the duration. Choose lighter colored drinks, and keep in mind that higher-quality spirits may be a better choice -- less-refined spirits may contain more congeners. For more information on alcohol and hangovers, see the links on the following page.