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Updated on August 1, 2023
7 min read

How Does Someone Reach a Lethal BAC Level?

Do you know the lethal consequences of severe alcohol intoxication due to excessive drinking? Most people have heard of the term “Blood Alcohol Concentration” (BAC) or “blood alcohol content.” However, many aren’t aware of how dangerously high levels of intoxication lead to potentially deadly results.

Understanding BAC and what limit you must reach to inflict a mortal consequence is key to drinking alcoholic beverages responsibly. This blog post explores how you can reach a lethal level of BAC. It also provides insight so you can learn more about the risks of drinking alcohol beyond your capacity.

What is Blood Alcohol Concentration (BAC)?

Blood Alcohol Concentration (BAC) measures the amount of alcohol (ethyl alcohol or ethanol) in your bloodstream. Shown as a percentage, BAC refers to the speed by which you absorb, distribute, metabolize, and get rid of the substance.

For example, if your BAC is 0.08%, .08 grams of alcohol are present in every 100 milliliters of your blood. If your BAC is 0.02%, you may experience symptoms like partial loss of judgment, relaxation, mild body warmth, and mood changes. 

BAC and Alcohol Metabolism

Blood alcohol level will determine what effects the alcohol will have on the body. The liver can only metabolize approximately one standard alcoholic drink per hour.

In many cases, one standard beverage means: 

  • 12 ounces (oz.) of beer
  • 5 oz. of wine
  • 1.5 oz. of whiskey 

If you have more than one drink within an hour, your BAC will be higher than that of someone who drank only one beverage within the same time frame.

Effects and Risks of High BAC

Even if you stop drinking alcohol or are unconscious, blood alcohol levels may not remain or decrease. Because the body continues to let alcohol pass into the bloodstream, the BAC can rise and cause serious health signs or symptoms. 

The higher the BAC, the more intense (and sometimes more dangerous) effects of alcohol. Signs of intoxication will be evident in many cases, particularly those who don’t participate in chronic drinking. Yet, tolerance among people who suffer from chronic alcohol abuse could mask these signs.

Doctors or law enforcement officials may use a breathalyzer or perform blood tests to figure out someone’s BAC. A breathalyzer is a device that measures the amount of alcohol in the breath.


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What is the Lethal Blood Alcohol Content Level?

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), a blood alcohol content level between 0.31% and 0.45% can be life-threatening. When you reach these numbers, there’s a significant risk of death.

Alcohol is a central nervous system (CNS) depressant. Extreme or excessive quantities of the substance can dramatically slow vital life functions like breathing.   

How Does Someone Reach This BAC Level?

Multiple factors can influence how the body absorbs and metabolizes alcohol. These elements can impact your BAC level: 

Amount of Alcohol (Number of Standard Drinks) 

The liver cannot metabolize more than one standard drink (14 grams of pure alcohol) in an hour. So, more than a standard alcoholic beverage within an hour will increase BAC. 

People who binge drink or drink heavily will experience a spike in BAC:

  • In binge drinking, men have five or more alcoholic beverages in less than 2 hours, while women have four or more drinks within the same time frame. 
  • In heavy drinking, men have four or more alcoholic beverages regardless of the day, while women have three3 or more drinks.

Whether binge or heavy drinking, the high amounts of alcohol overwhelm the body’s metabolic processes. This makes BACs rise quickly. 


Because of biological differences, women have more trouble breaking down alcohol than men. This means that women will have increased BACS in shorter times than men. 

Three main reasons can explain why this occurs:

  • Body composition: Compared to men, women have a higher body fat percentage yet a lower water percentage. Alcohol accumulates in the bloodstream more often in women than men because fat cannot dissolve the beverage. 
  • Stomach ADH: ADH (alcohol dehydrogenase) is an alcoholic-metabolizing enzyme commonly found in men’s stomachs. Because of this, men can metabolize much more alcohol than women before the beverage reaches the bloodstream. 
  • Liver ADH: Breaking down alcohol requires ADH in the liver. However, this process isn’t as efficient in women’s livers as in men’s, contributing to an increased BAC. 

Lastly, hormones play a role in alcohol metabolism. When women have periods, BAC may be higher because of hormone changes. 

Body Weight

Your weight can define the amount of space by which alcohol diffuses in the body. For example, those weighing 130 pounds could have two beers and a lower BAC than those weighing less and drinking the same quantity. 

Similarly, someone with more muscle mass can absorb and break down alcohol more efficiently than those with a higher body fat percentage. Alcohol doesn’t dissolve in fat. 

The accuracy of BAC tests can vary depending on when it was performed. A blood alcohol test provides the most accurate results when done within 6 to 12 hours after the last consumed alcoholic beverage. 

Body Size

Like body weight, body size can influence the speed of alcohol absorption and metabolism. Even if alcohol consumption remains, smaller body frames could have increased BACs than those with more sizable body frames.

Stomach Contents

A higher BAC can also occur if you drink on an empty stomach. If you drink alcohol, eat beforehand. Food high in protein can help lower alcohol processing in the body. Eating before drinking minimizes the likelihood of overwhelming the liver and reaching a dangerous BAC level. 


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What BAC Level Causes Alcohol Poisoning? 

People with a 0.0 percent BAC are sober and don’t risk alcohol poisoning (alcohol intoxication). However, if the BAC level increases, the risk of alcohol poisoning also rises. 

At 0.08 percent BAC, you’re legally intoxicated. In the U.S., people with a 0.08 percent BAC or higher while driving can face criminal charges for drunk driving. In some states, like Utah, it’s 0.05 percent. 

Alcohol poisoning could occur in those whose BAC levels fall between 0.250-0.399 percent. You may lose consciousness at this point, and the risk of death is extremely high. There are at least 2,200 alcohol poisoning deaths annually.


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Signs of Alcohol Intoxication (Poisoning) 

The effects of alcohol intoxication may not always be visible. Thus, direct blood analysis and breath testing can accurately determine how much alcohol is in the bloodstream. 

The most common signs of this level of intoxication include:

  • Disorientation, delayed reaction time, lack of coordination, or inability to walk
  • Depression
  • Rapid involuntary eye movement
  • Changes in speech volume
  • Red eyes
  • Mental confusion
  • Slurred speech
  • Amnesia
  • Bluish-colored or cold, clammy skin (sweating)
  • Trouble staying conscious
  • Hypothermia (lower than average body temperature)
  • Irregular heartbeat (arrhythmias) or breathing (10-second intervals or more between breaths)
  • Incontinence (inability to control bladder or bowel)
  • Seizures
  • Vomiting or choking
  • Unresponsiveness
  • Strong alcohol smell 

If you visit an emergency department, doctors may evaluate these signs: 

  • A known history of chronic use
  • Possible use of another substance
  • The degree of impairment (slight, moderate, very, or extreme) 

When Should You Visit the Emergency Room (ER)?

If you suspect you or a loved one is experiencing alcohol poisoning, seek immediate medical help. Don’t wait for symptoms to appear; some may not show signs typically associated with a particular BAC. 

Also, avoid giving cold showers or hot coffee to someone experiencing alcohol poisoning. These actions could worsen the situation and cause more problems. If you know someone has drunk too much quickly, seek help immediately.

A study suggests that chronic drinkers may have built tolerance. This could cover up visible signs of intoxication when BACs are over 100 mg/100 ml.

Treatment for Alcohol Abuse & Addiction

If you or a loved one has an alcohol use disorder (AUD), getting professional medical help is the first step toward recovery. Different therapeutic options/resources are available, such as:

  • Cognitive-behavioral therapy (CBT)
  • Inpatient/outpatient treatment facilities
  • Support groups 
  • Medication-assisted treatment (MAT)

Don’t quit drinking suddenly. Withdrawal symptoms can be severe, and the risk of relapse and overdose increases. Treatment facilities provide medical supervision to help you undergo a healthy, controlled detox and withdrawal process.


You can reach a lethal BAC level when drinking alcohol heavily. Women have increased BACs in shorter times than men due to body composition, stomach ADH, and liver ADH.

Body weight, size, and content also influence the speed of absorption. Signs of intoxication (BAC 0.250-0.399 percent) may include mental confusion, disorientation, amnesia, irregular heartbeat, and hypothermia.

If you or a loved one is at risk of alcohol poisoning, seek help immediately. Don’t quit drinking suddenly due to withdrawal symptoms and the increased risk of relapse and overdose. Seek professional medical assistance to undergo a proper detox.

Updated on August 1, 2023
7 sources cited
Updated on August 1, 2023
All Alcoholrehabhelp content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies.
  1. Alcohol.” University of Notre Dame.

  2. “Alcohol Poisoning: Symptoms, Treatment & Prevention.” Cleveland Clinic, 2020.

  3. MedlinePlus. Blood Alcohol Level.” U.S. National Library of Medicine, 2022.

  4. The Alcohol Pharmacology Education Partnership. “Summary of Differences Between Girls ‘n Guys. Duke University, n.d.

  5. Olson et al. “Relationship Between Blood Alcohol Concentration and Observable Symptoms of Intoxication in Patients Presenting to an Emergency Department.” Alcohol and Alcoholism, 2013.

  6. Understanding the Dangers of Alcohol Overdose.National Institute on Alcohol Abuse and Alcoholism, 2023.

  7. Zakhari, S. “Overview: How Is Alcohol Metabolized by the Body?”, National Institute on Alcohol Abuse and Alcoholism, 2006.

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All content created by Alcohol Rehab Help is sourced from current scientific research and fact-checked by an addiction counseling expert. However, the information provided by Alcohol Rehab Help is not a substitute for professional treatment advice.
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