Alcohol-Induced Blackouts: Blackout From Drinking Causes
Written by Theresa Valenzky
& Medically Reviewed by Benjamin Caleb Williams, RN
Medically Reviewed
Up to Date
Last Updated - 6/17/2022
View our editorial policyAlcohol blackouts are when alcohol completely inhibits your ability to form new memories. They appear as blank periods of time in your memory. Even though someone may act completely normal while experiencing an alcohol blackout, they cannot remember anything that happened during the blackout once they become sober.
Alcohol-induced memory loss, often called a “blackout,” is a common side effect of excessive alcohol consumption (i.e., binge drinking). Blackouts are a breakdown in the transfer of information from short-term to long-term storage. Blackouts can lead to problems if you need to remember something that occurs during the blackout. If you sustained an injury while inebriated, had intercourse or got into legal problems or any other situations, the inability to recall what happened can lead to significant issues later.
Types of Blackouts
Generally speaking, there are two types of alcohol-induced blackouts:
- Fragmentary blackouts: Fragmentary blackouts indicate that alcohol-related memory loss is partial. The terms “brownout” or “gray-out” have been used to distinguish fragmentary blackouts from en bloc blackouts. Fragmentary blackouts often include memories that can be recalled with an appropriate cue.
- En bloc blackouts: An en bloc blackout indicates that complete memory loss for the hours surrounding excessive alcohol use has occurred. En-bloc blackouts are usually associated with higher blood alcohol content.
Fragmentary blackouts can occur with a breath alcohol concentration (BrAC) as low as 0.06 g/dL, but most evidence indicates that blackouts are associated with a BrAC of at least 0.14 g/dL and more commonly at a level of 0.20 g/dL or greater.
Blackouts vs. Brownouts
Technically, “blackout” and “brownout” are slang words, not medical terms. The term “brownouts” is generally used to refer to fragmentary blackouts where pieces of what happened can be recalled or where parts of memory return. The term “blackout” describes a blackout where the memory never formed and cannot be remembered, no matter how hard you try.
Blackouts vs. Passing Out
It is important to distinguish between alcohol-induced blackouts and unconsciousness: Blackouts occur when people are conscious and can interact with and respond to their environment in some capacity. Unconsciousness is a state where someone cannot interact with or respond to their environment. During unconsciousness, memories are not formed because someone is unaware of what is happening. During a blackout, someone is aware of what is happening but will not be able to remember it later.
What Causes Alcohol Blackouts?
The most obvious factor that contributes to alcohol-related amnesia is the amount of alcohol consumed. If you drink more than your body can metabolize, you risk experiencing a blackout. The liver can metabolize approximately one drink per hour and a half. Unmetabolized alcohol remains in the bloodstream, which is why blood alcohol content (BAC) rises as you continue to consume alcohol.
While it is known that some people are more prone to alcohol-induced amnesia than others, the reason for this difference is unclear. Intrinsic factors like genetics, weight and nourishment play a role, as do extrinsic factors like alcohol tolerance, the presence of other drugs and exercise frequency.
- Genetics: Just as alcohol addiction is often tied to genetics, blacking out may also be tied to genetics. Recent studies have indicated that alcohol blackouts tend to run in families.
- Weight: Your body weight will affect your risk of blacking out. The less you weigh, the easier it will be for you to consume too much alcohol.
- Nourishment: You are more vulnerable to a blackout if you drink while malnourished. Often, people who struggle with alcoholism don’t get the proper nutrition they need. Even if you don’t drink on an empty stomach, regularly drinking alcohol may interfere with your ability to absorb nutrients from your food.
How Can You Tell if Someone Is Blackout Drunk?
It is not possible to tell for sure if someone is blackout drunk until after they are sober and unable to recall anything that happened. It may be possible, however, to get a strong idea that someone is blackout drunk if they appear unable to remember things that happened at least a few minutes previously. This can indicate that their short-term memories are not being stored, and they are blacking out.
Risks of Alcohol Blackouts
- Accidents and injuries: During a blackout, the inability to remember anything beyond a few minutes previously can increase the risk of accidents or injuries.
- Inability to remember risky behavior: Alcohol can reduce inhibitions, leading to risky behaviors such as unsafe sex, drug use or violent behavior. The inability to remember these events can create significant problems.
- Legal consequences: If someone commits a crime during an alcohol blackout, they may face legal consequences even if they can’t remember what they did.
- Mental health issues: Regular alcohol blackouts can lead to mental health issues, such as anxiety, depression and an increased risk of suicide.
- Increased risk of addiction: Regularly drinking to the point of blackout increases the likelihood of developing an alcohol use disorder.
- Strained relationships: Unremembered behaviors during blackouts can cause problems in relationships with family, friends and coworkers.
- Potential for overdose: Drinking enough to cause a blackout increases the risk of alcohol poisoning, which can be fatal.
How To Prevent Blackouts
- Stay hydrated: Dehydration from alcohol consumption results from alcohol’s ability to increase urinary output. Staying hydrated while drinking alcohol is important for controlling intoxication and can also limit the severity of the next-day hangover.
- Eat a meal: Alcohol is absorbed in the small intestine, so eating food when you are drinking alcohol can slow alcohol absorption.
- Slow down: Reducing your rate of alcohol consumption is a reliable way to avoid alcohol-induced amnesia.
- Drink less: Alcohol blackouts occur from drinking a lot of alcohol at once. Cutting back can prevent blackouts from occurring.
- Mocktails: Alcohol-free cocktails, or “mocktails,” can be delicious, even healthy alternatives to alcoholic cocktails. Many websites provide mocktail recipes.
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Sources
National Institute on Alcohol Abuse and Alcoholism. “Alcohol Facts and Statistics.” August 2018. Accessed September 16, 2019.
Hermens, Daniel F; Lagopoulos, Jim. “Binge Drinking and the Young Brain: A Mini Review of the Neurobiological Underpinnings of Alcohol-Induced Blackout.” Frontiers in Psychology, January 2018. Accessed September 16, 2019.
Wetherill, Reagan; Fromme, Kim. “Alcohol-Induced Blackouts: A Review of Recent Clinical Research with Practical Implications and Recommendations for Future Studies.” Alcoholism, Clinical and Experimental Research, May 2016. Accessed September 16, 2019.
Zorumski, Charles F. “What Causes Alcohol-Induced Blackouts?” Scientific American, October 2018. Accessed September 16, 2019.
White, Aaron M. “What Happened? Alcohol, Memory Blackouts, and the Brain.” Alcohol Research & Health, 2003. Accessed September 16, 2019.
U.S. Department of Justice. “Bureau of Justice Statistics: Alcohol and Crime.” April 1998. Accessed September 17, 2019.
National Institute on Alcohol Abuse and Alcoholism. “Alcohol’s Damaging Effects on the Brain.” Alcohol Alert, October 2004. Accessed September 17, 2019.
Marino, Elise N; Fromme, Kim. “Alcohol-induced blackouts and maternal family history of problematic alcohol use.” Addictive Behaviors, June 2015. Accessed September 16, 2019.
Leasure, J. Leigh; Neighbors, Clayton; Henderson, Craig E; Young, Chelsie M. “Exercise and alcohol consumption: what we know, what we need to know, and why it is important.” Frontiers in Psychiatry, November 2015. Accessed September 16, 2019.
View Sources
National Institute on Alcohol Abuse and Alcoholism. “Alcohol Facts and Statistics.” August 2018. Accessed September 16, 2019.
Hermens, Daniel F; Lagopoulos, Jim. “Binge Drinking and the Young Brain: A Mini Review of the Neurobiological Underpinnings of Alcohol-Induced Blackout.” Frontiers in Psychology, January 2018. Accessed September 16, 2019.
Wetherill, Reagan; Fromme, Kim. “Alcohol-Induced Blackouts: A Review of Recent Clinical Research with Practical Implications and Recommendations for Future Studies.” Alcoholism, Clinical and Experimental Research, May 2016. Accessed September 16, 2019.
Zorumski, Charles F. “What Causes Alcohol-Induced Blackouts?” Scientific American, October 2018. Accessed September 16, 2019.
White, Aaron M. “What Happened? Alcohol, Memory Blackouts, and the Brain.” Alcohol Research & Health, 2003. Accessed September 16, 2019.
U.S. Department of Justice. “Bureau of Justice Statistics: Alcohol and Crime.” April 1998. Accessed September 17, 2019.
National Institute on Alcohol Abuse and Alcoholism. “Alcohol’s Damaging Effects on the Brain.” Alcohol Alert, October 2004. Accessed September 17, 2019.
Marino, Elise N; Fromme, Kim. “Alcohol-induced blackouts and maternal family history of problematic alcohol use.” Addictive Behaviors, June 2015. Accessed September 16, 2019.
Leasure, J. Leigh; Neighbors, Clayton; Henderson, Craig E; Young, Chelsie M. “Exercise and alcohol consumption: what we know, what we need to know, and why it is important.” Frontiers in Psychiatry, November 2015. Accessed September 16, 2019.
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