What is Functional Tolerance to Alcohol?

Alcohol is a depressant that affects both bodily functions and human behavior. However, when someone consumes alcohol on a regular basis, he or she develops a tolerance to the effects of alcohol. When someone develops a “tolerance to alcohol,” it means that they have consumed so much alcohol consistently, that now they need more alcohol to produce the same effect that used to be produced with less alcohol.

It’s just like drug abuse, only with alcohol – the effects become unnoticeable over time and the drinker needs more alcohol to feel its pleasurable effects. According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), “Tolerance to alcohol’s effects influences drinking behavior and drinking consequences in several ways.” When someone has developed a tolerance to alcohol, they are putting themselves at serious risk.

The NIAAA says tolerance to alcohol may encourage:

  • Alcohol consumption
  • Alcohol dependence
  • Organ damage
  • Driving under the influence
  • Toxicity of other drugs
  • Ineffectiveness of other drugs
  • Risk of alcoholism

Essentially, humans develop a tolerance to alcohol when brain functions begin to adapt to compensate for disruptions (in behavior and bodily functions) caused by drinking. This adaption is technically referred to as “functional tolerance.”

If someone is a chronic heavy drinker, he or she will display “functional tolerance” when they have a high blood alcohol concentration (BAC), but they’ll show very few signs of intoxication, which in other people without a high tolerance would experience slurred speech, balance issues, vomiting, unconsciousness, or even a fatal overdose.

When someone has a high tolerance for alcohol, they can drink a lot of alcohol and not feel its effects. Because of this, they may continue drinking even more so they can feel a “buzz.” This vicious cycle can lead to alcohol dependence and serious organ damage.

Note: Functional tolerance does not impact blood alcohol concentration or BAC. Just because someone has a high tolerance to alcohol, it does not mean their BAC is lower. Quite the contrary, tolerance has zero effect on BAC.

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