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Blackout Drunk: Signs, Causes & Dangers of Blackout Drinking

3 min read · 7 sections

Blackouts, or temporary losses of memory, can result from excessive alcohol consumption and can occur in anyone of any age or level of alcohol experience who drinks alcohol.1 One study reports that approximately 50% of people that drink alcohol experience blackouts at some point in their lifetime.2

Learning more about blackouts can help you understand why you should take control of your alcohol use. Education on blackouts may help you avoid potential negative consequences of drinking alcohol and protect your health and well-being.

American Addiction Centers offers a free alcohol addiction hotline 24/7 for those who are looking for help with an alcohol addiction. Call There, an admissions advisor can discuss your situation, formulate a treatment plan, and verify your insurance coverage over the phone.

What is a Blackout?: Signs & Symptoms

According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), alcohol-induced blackouts refer to “gaps” in a person’s memory for events that occurred while they were intoxicated.1

People often confuse “blacking out” with “passing out,” also called syncope, which is a temporary loss of consciousness where a person no longer displays voluntary behaviors. However, an alcohol-related blackout involves losing your memory while you’re still awake and conscious; you can be moving around, interacting with others, and seem fine to those around you. Blackouts are caused by drinking high quantities of alcohol, which leads to an impairment in the way your brain transfers memories from short- to long-term memory.1

People can experience two different types of blackouts when they drink enough alcohol. If you experience a fragmentary blackout, also known as a “grayout” or “brownout”, you may have gaps in your memory combined with some level of recollection of events, whereas a total blackout involves no recollection of events, because memories of what happened never form and if they do, you cannot access them. People with this type of blackout, also called an “en bloc” blackout, have amnesia that can last for many hours. It can feel like you weren’t there for the events that occurred.1

A person can progress from blacking out to passing out.1 Passing out, or losing consciousness, as a result of drinking is a sign of an alcohol overdose, a medical emergency that should prompt witnesses to dial 9-1-1 for help.3,4

The signs or symptoms of blackouts can be challenging to identify because people who black out are completely able to engage in complex behaviors. According to the NIAAA, people who black out may engage in conversations, drive automobiles, and perform other behaviors, such as spending money, conversing with others, or having unprotected sex, that they can’t recall later on. People don’t remember these behaviors because their memories are not transferred into their mind’s long–term storage.5,6

Symptoms that may occur, are similar to symptoms of intoxication, and may include:

  • Dizziness
  • Headaches
  • Muscle spasms
  • Vision changes
  • Difficulty speaking

Though as mentioned earlier, the person may not be aware that they are blacked out.

Causes of Blackouts

Many people who experience blackouts do so because of binge drinking but they can also occur when people combine certain medications (like benzodiazepines) and alcohol.1

According to the Centers for Disease Control and Prevention (CDC), binge drinking occurs when a man has 5 or more drinks or a woman has 4 or more drinks in about 2 hours; it might also include a pattern of drinking that raises your blood alcohol content (BAC) to 0.08g/dl or more.7 Blackouts usually occur when your BAC is 0.16% or higher.1 Blackouts mainly occur when people ingest alcohol too quickly, so their body is not able to effectively process it out of their systems. The overload of alcohol in your bloodstream causes a rapid increase in BAC, which can increase the risk of blackouts.1

What Happens to Your Body When You Blackout?

The technical term for the type of memory loss that people typically experience during a blackout is known as anterograde amnesia. This means that you cannot form or store new memories. While scientists don’t fully understand the chemical mechanisms behind blackouts, they know a specific area of your brain, known as the hippocampus, which is responsible for memory, no longer functions properly when someone experiences this phenomenon.8 Alcohol is believed to change the way that important receptors in your brain act. This leads to the impairment of steroid production, which weakens the connection between brain cells and can impact learning and memory.9

Furthermore, using certain medications, especially when combined with alcohol, such as benzodiazepines like diazepam, “z-drugs” used for insomnia like zolpidem (Ambien), and marijuana, can increase the risk of temporary memory lapses and blackouts, especially in younger people.6,10

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Take our free, 5-minute alcohol abuse self-assessment below if you think you or someone you love might be struggling with alcohol abuse. The evaluation consists of 11 yes or no questions that are intended to be used as an informational tool to assess the severity and probability of an alcohol use disorder. The test is free, confidential, and no personal information is needed to receive the result.

Short-Term and Long-Term Effects of Heavy or Excessive Drinking

If you misuse alcohol in ways that are harmful to your health, including binge drinking, or high-intensity drinking, you can experience many different short- and long-term effects that can occur in addition to blackouts.1,7,11

The short-term effects of alcohol misuse can include:11,12

Alcohol misuse over long periods of time can contribute to the development of many serious consequences, including:11

  • Heart disease.
  • Stroke.
  • Liver damage.
  • Liver cancer.
  • Breast cancer.
  • Bowel cancer.
  • Pancreatitis.

Frequently Asked Questions: Blackouts

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  1. National Institute on Alcohol Abuse and Alcoholism. (2021, March). Interrupted Memories: Alcohol-Induced Blackouts.
  2. Wetherill, R. R., & Fromme, K. (2016). Alcohol-induced blackouts: a review of recent clinical research with practical implications and recommendations for future studies. Alcoholism, clinical and experimental research, 40(5), 922–935.
  3. National Institute on Alcohol Abuse and Alcoholism. (2021, May). Understanding the dangers of alcohol overdose.
  5. National Institute on Alcohol Abuse and Alcoholism. (2004, October). Alcohol’s damaging effects on the brain. Alcohol alert, 63.
  6. White, A. (2003). What happened? Alcohol, memory blackouts, and the brain. Alcohol Research & Health, 27(2), 186-96.
  7. Centers for Disease Control and Prevention. (2019, December 30). Binge drinking.
  8. Sorumski, C. (2018, October 26). What causes alcohol-induced blackouts?
  9. Dryden, J. (2011, July 6). The biology behind alcohol-induced blackouts.
  10. Chavant, F., Favrelière, S., Lafay-Chebassier, C., Plazanet, C., & Pérault-Pochat, M. C. (2011). Memory disorders associated with consumption of drugs: updating through a case/noncase study in the French PharmacoVigilance DatabaseBritish journal of clinical pharmacology72(6), 898–904.
  11. (2018, August 21).
  12. Schuckit, M. A. (1996). Alcohol, anxiety, and depressive disorders. Alcohol health and research world, 20(2), 81–85.
  13. National Institute on Alcohol Abuse and Alcoholism. (n.d.). Facts about alcohol overdose (or “alcohol poisoning”).
  14. National Institute on Aging. (2017, May 16). Facts about aging and alcohol.
  15. Schoeler, T., & Bhattacharyya, S. (2013). The effect of cannabis use on memory function: an updateSubstance abuse and rehabilitation4, 11–27.
  16. National Institute on Aging. (2020, October 21). Memory, forgetfulness, and aging: What’s normal and what’s not?
  17. Lee, H., Roh, S. & Kim, D. (2009). Alcohol-induced blackout. International journal of environmental research and public health, 6(11), 2783-2792.
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