Tequila is a distilled spirit made exclusively from the blue agave plant. Its primary psychoactive component, ethanol, is a small, water-soluble molecule that quickly interacts with almost every system. Understanding the effects of tequila involves following the path of ethanol from the moment it is swallowed through to its complete breakdown and elimination. This process includes rapid absorption into the bloodstream, changes in brain chemistry, and detoxification by the liver.
Absorption and Initial Effects
The physiological effects begin as ethanol enters the circulatory system. While some absorption occurs in the mouth and stomach, the majority happens rapidly in the small intestine due to its large surface area.
The rate alcohol enters the bloodstream, measured as Blood Alcohol Concentration (BAC), is influenced by external factors. Drinking on an empty stomach leads to a faster and higher BAC peak because contents quickly pass into the small intestine. Conversely, consuming food, especially meals rich in fat, protein, and fiber, slows absorption by delaying gastric emptying.
As the BAC rises, the first physical signs include warmth, relaxation, and disinhibition. Ethanol is distributed throughout the body’s water content, quickly reaching organs with rich blood supplies like the brain. Intoxication is directly tied to the speed and concentration of ethanol delivery to the central nervous system.
The Brain’s Response: Intoxication
Once ethanol crosses the blood-brain barrier, it acts as a central nervous system depressant by altering the activity of key neurotransmitters. This interaction leads to the characteristic signs of intoxication.
Ethanol primarily enhances the effects of gamma-aminobutyric acid (GABA), the brain’s main inhibitory neurotransmitter. By facilitating the activity of GABA-A receptors, ethanol “puts the brakes” on neural communication. This inhibitory signaling causes sedation, reduced anxiety, muscle relaxation, and impaired motor coordination, resulting in slurred speech and unsteady gait.
Simultaneously, ethanol inhibits N-methyl-D-aspartate (NMDA) receptors, which are activated by the excitatory neurotransmitter glutamate. Blocking these receptors disrupts long-term potentiation, a process fundamental to memory formation. The combined effect of boosting inhibitory signals and blocking excitatory ones leads to impaired decision-making and memory lapses.
Metabolism and Detoxification
Detoxification primarily takes place in the liver, where ethanol is converted into less harmful substances through a two-step enzymatic pathway. First, Alcohol Dehydrogenase (ADH) converts ethanol into acetaldehyde, a highly reactive and toxic compound.
Second, Aldehyde Dehydrogenase (ALDH) processes acetaldehyde into acetate. Acetate is a harmless substance that the body can break down or use as an energy source. The speed of this metabolic process is constant, meaning the body clears alcohol at a steady rate.
Genetic variations in ADH and ALDH genes affect the speed of metabolism. Less efficient ALDH variants cause acetaldehyde to build up rapidly, leading to a flushed face, nausea, and an accelerated heart rate. Genetics and biological sex contribute to individual differences in how quickly the body converts ethanol into acetate.
The Next Day: Understanding the Tequila Hangover
The unpleasant symptoms experienced the morning after drinking are the result of several physiological consequences. A major factor is the lingering presence of acetaldehyde, especially if the liver’s ALDH enzymes were overwhelmed by excessive consumption. The accumulation of this toxic metabolite is responsible for much of the nausea, headache, and general malaise associated with a hangover.
Another cause of hangover symptoms is dehydration, induced by alcohol suppressing the anti-diuretic hormone, vasopressin. Vasopressin normally signals the kidneys to conserve water, but its inhibition leads to increased urine production. This excessive fluid loss results in dehydration, which manifests as thirst and contributes directly to the throbbing headache often felt the next day.
The third factor involves congeners, complex organic molecules produced during fermentation and aging that give spirits their distinct flavors and aromas. Aged, or añejo, tequilas typically contain higher levels of these congeners than clear spirits like vodka. Research suggests that a higher congener content can increase the severity of hangover symptoms.