Dark liquors are more likely to cause worse hangovers than clear liquor. This is because congeners, the byproducts of alcohol production found primarily in red wine, brandy, and tequila, are found in dark liquors. Congeners make hangovers worse and last longer. Clear liquors have fewer congeners, such as vodka, silver rum, and gin. Alcohol and its congeners cause inflammation, contributing to malaise and hangovers.