What is Alcohol Tolerance?

Alcohol tolerance, dependence and addiction are closely intertwined. Some people can drink large amounts of alcohol without appearing drunk, while others around them are visibly intoxicated after consuming the same number of drinks. The person who doesn’t appear drunk likely has a higher alcohol tolerance.

What is Alcohol Tolerance?

Tolerance to a substance means that a person needs more of it to get the same effects as when they first started using it. Often, someone who has been drinking for a long time needs more alcohol to feel drunk than someone who rarely drinks. However, if their blood alcohol levels (BACs) were tested, the person who drinks often and does not feel drunk may have the same BAC as the person who rarely drinks but feels drunk. This phenomenon is called alcohol tolerance.

Alcohol Tolerance vs. Dependence

Although tolerance and dependence are closely linked, they are not the same. Tolerance develops when a person needs increasing amounts of a substance to get the same effects as when they first started using it. Dependence to a substance has developed, when a person who stops using the substance, experiences withdrawal symptoms and cravings.

Dependence can be physical or psychological. Some substances only lead to psychological addiction, while others can lead to physical addiction.

• Psychological dependence: Cravings for a substance are due to psychological dependence. The mind creates a desire for the drug and focuses on that need.
• Physical dependence: With physical dependence, the cells in the body become so dependent on the substance that they need it to function. Without the substance, the body goes into withdrawal. Physical withdrawal symptoms from alcohol can be very dangerous and include seizures and delirium tremens.

Alcohol dependence is often both psychological and physical. Together, dependence and tolerance can lead to addiction. Addiction involves a person continuing to use a substance despite negative consequences.

Causes of Alcohol Tolerance

Many causes of alcohol tolerance exist. Although many of them are outside a person’s control, some depend on behavior. For instance, some people deliberately drink excessively to build up a tolerance to alcohol — including about 10% of college students. Other causes of alcohol tolerance include:

• Genes: Many genes impact a person’s sensitivity to alcohol. One of these genes controls the production of alcohol dehydrogenase, or ADH, the liver enzyme that breaks down alcohol. Alcohol dehydrogenase formation is controlled by genes called ADH genes. Two forms of ADH genes are known to exist, ADHS and ADHF. People who inherit the ADHS gene from both parents are more likely to have a low tolerance to alcohol.
• Ethnicity: Some ethnicities, like Asian and Polynesian populations, are less likely to develop alcohol tolerance. Doctors think this may be due to a gene called ADH1B*2 that is more common in those groups.
• Body Type: People who have more body fat may have less alcohol tolerance than people with more muscle. Alcohol does not easily get into fat, which forces more alcohol into the bloodstream. In turn, the BAC rises.
• Gender: Women often get drunk faster than men for several reasons:
  • Women may produce less ADH than men
  • Women often have more body fat than men, and alcohol does not diffuse into fat
  • Women usually have less blood volume of men, so their BAC rises more than men’s
• Metabolism: The ability of the body to make enough ADH has an important impact on tolerance. The more ADH the body can make, the more a person metabolizes alcohol and can tolerate higher quantities. Some substances reduce alcohol tolerance by interfering with ADH and other enzymes, like:
  • Bupropion, which is used for mood and smoking cessation
  • Verapamil, which is used for blood pressure and some heart problems
  • Efavirenz, an HIV medication

Types of Alcohol Tolerance

Doctors have found that there are many subtypes of alcohol tolerance. Although some are genetically determined, others are not. Further, these subtypes can occur in different situations. They may even occur at the same time in some people. Doctors think that if a person can function normally with a BAC of 0.15, then they may be tolerant to alcohol. Subtypes of tolerance include:

• Functional tolerance: This subtype develops when brain cells learn to compensate for high BAC levels. A chronic heavy drinker may have a high BAC but may not have any outward signs of being drunk because their body has learned to adapt.
• Acute tolerance: Impairment from drinking can be worse at the beginning of a drinking session than at the end of it, even if the BAC is the same.
• Environment-dependent tolerance: Drinking repeatedly in the same place or with the same people, like with friends in a bar, can cause less impairment than if the same amount is drunk in a different place.
• Learned tolerance: People who learn or practice a task, such as a game, when they are drinking develop tolerance more quickly.
• Environment-independent tolerance: Similar to functional tolerance, this kind of tolerance occurs when a person’s BAC is high. However, it takes longer to develop than environment-dependent tolerance.
• Metabolic tolerance: As the liver is exposed to higher BAC levels, it begins to produce extra enzymes that break down alcohol.

How Long Does Alcohol Tolerance Last?

The body tries to adapt quickly to changing circumstances. Therefore, if a person stops drinking, their tolerance will decrease. How long this process takes can vary from person to person. However, in general, alcohol tolerance can be reversed within one or two months.

How to Lower Alcohol Tolerance

Sometimes alcohol tolerance can be lowered due to factors outside a person’s control, like their age. People often lose tolerance for alcohol as they age or when they start medications that interact with alcohol. However, the best way to lower alcohol tolerance is to stop or cut back on drinking. Tolerance develops because the body is trying to compensate and keep functional despite having a high BAC. By reducing drinking, a person is saving their body the work of having to do this to keep working properly. A person’s tolerance will, therefore, naturally decrease over time. Tips to reduce tolerance include:

• Reduce the number of days a person drinks every week
• Figure out drinking triggers and replace them with other behaviors

Getting Help With Alcohol Addiction

If you or a loved one struggle with alcohol use, help is available. Contact The Recovery Village Ridgefield to speak with a representative about how professional treatment can address a substance use disorder and any co-occurring mental health disorders. Take the first step toward a healthier future, call today.