The experience of feeling sick after drinking one clear spirit, like vodka, while feeling fine after another, like tequila, is a common but confusing phenomenon. Since the primary intoxicating ingredient, ethanol, is the same in both, the difference in physical reaction must be due to the other components in the drink, how your body processes them, or the circumstances of consumption. The specific origins and production methods of each spirit introduce subtle chemical variations that can interact uniquely with an individual’s biology.
Defining the Chemical Differences in Spirits
Vodka and tequila begin their lives with fundamentally different raw materials, resulting in distinct chemical profiles before the final bottling. Vodka is traditionally distilled from a variety of sources, including grains like wheat, rye, or corn, or starchy vegetables such as potatoes. The production goal is a neutral spirit, achieved through multiple distillations and heavy filtration to remove almost all compounds other than water and ethanol. Tequila, by contrast, must be made from the blue agave plant. The agave core is cooked to convert starches into fermentable sugars, a process that imparts unique compounds into the final product.
Congeners, Impurities, and the Filtering Paradox
The non-ethanol compounds created during fermentation and distillation are known as congeners, and they include substances like methanol, acetone, and fusel oils. While ethanol is the main cause of intoxication, a higher concentration of congeners is associated with a more severe hangover because these compounds are mildly toxic. Vodka is often cited as having one of the lowest congener contents of any spirit due to its extensive distillation and filtration process, which strips away most of these byproducts. Tequila, particularly unaged blanco tequila, is also generally low in congeners, second only to vodka. Alternatively, the very lack of flavor in highly filtered vodka might encourage faster consumption, leading to a quicker onset of sickness symptoms.
Individual Body Chemistry and Acetaldehyde
The most significant factor in alcohol-induced sickness is the body’s metabolic process, which converts ethanol into a highly toxic compound called acetaldehyde. This conversion is managed by the enzyme Alcohol Dehydrogenase (ADH), which breaks down the ethanol you consume. Acetaldehyde is responsible for many unpleasant symptoms, including nausea, flushing, and headaches, because it is 10 to 30 times more toxic than ethanol. The body then relies on a second enzyme, Aldehyde Dehydrogenase (ALDH), to quickly convert acetaldehyde into harmless acetate. If your ALDH enzyme is less efficient, perhaps due to genetic variation, acetaldehyde builds up in your system, causing a severe physical reaction known as alcohol sensitivity.
Context, Mixers, and Speed of Consumption
Factors outside of the spirit’s chemical makeup often play a powerful role in the perceived severity of sickness. Vodka is frequently consumed in cocktails mixed with carbonated and sugary sodas or energy drinks. Carbonation can accelerate the movement of alcohol from the stomach to the small intestine, leading to a faster spike in blood alcohol concentration (BAC) and more immediate feelings of intoxication and sickness. Sugary mixers, particularly those with artificial sweeteners, may also lead to a higher BAC compared to sugar-sweetened mixers, which can slow gastric emptying. Tequila, conversely, is often consumed as a shot with salt and lime or in a less-carbonated margarita, which may encourage a more moderate pace.