Understanding Blacking Out: Common Blackout Causes and How To Prevent Them

Medically Reviewed By:

Dr. Po-Chang Hsu, M.D., M.S.

Last medically reviewed June 24, 2024

Blacking Out

Key Points

  • Blacking out, caused by alcohol or drug use, is a widespread concern affecting diverse demographics.
  • Understanding blackouts involves recognizing partial or complete memory loss during intoxication.
  • Neurotransmitter effects and hippocampal disruption contribute to the occurrence of blackouts.
  • Substances like alcohol, benzodiazepines, and barbiturates are known to induce blackouts.
  • Health ramifications include physical injury, mental health issues, and long-term cognitive impairment
  • Prevention strategies include moderating consumption, knowing personal limits, and avoiding substance mixing.

Blacking out due to alcohol or drug use is a significant health concern that can impact individuals of various ages and backgrounds. Understanding these memory lapses and how they occur is paramount in creating and employing strategies to prevent them.

What Does ‘Blacking Out’ Mean?

Blacking out refers to a period in which you experience partial or complete memory loss. During a blackout, you are unable to recall events that occurred while being intoxicated. This ‘blackout’ is temporary, and your brain cannot form new memories. This is often a product of overindulgence in substances like alcohol and drugs that harm your brain’s functions. Blackouts tend to begin at blood alcohol concentrations (BACs) of about 0.16 percent (nearly twice the legal driving limit) and higher.[1]

Two types of blackouts can affect your memory. In a partial blackout, you may have spotty or fragmented memories of events that occurred while you were under the influence. You may remember some parts of this period but not others. This may also be referred to as a ‘brownout.’

If you suffer a complete blackout, you’ll have no memory whatsoever of what happened during your time of intoxication – your memory loss is total for that time frame. As such, you may only learn of events and your actions via the recollection of others.

How Blackouts Occur

The science behind blackouts can be eye-opening. Here’s a primer:[2]

  • Neurotransmitters: Substances like alcohol and benzodiazepines affect the neurotransmitters in your brain – specifically gamma-aminobutyric acid, or GABA. GABA is an inhibitory neurotransmitter that reduces neuronal excitability throughout the nervous system. Alcohol enhances the effects of GABA, leading to sedation, relaxation, and impairment of brain functions.
  • Hippocampus: The hippocampus is a part of the brain that forms new memories and transfers short-term memories to long-term storage. Alcohol and some drugs can interfere with the functioning of your hippocampus. They disrupt the ability of neurons located in your hippocampus to communicate effectively. This makes the encoding of new memories less effective.
  • Dosage and blood alcohol concentration (or BAC): The likelihood of experiencing a blackout depends on the amount of alcohol or drug that you consume, as well as your level of tolerance. Binge drinking greatly increases the risk of a blackout. Your blood alcohol level also plays a critical role. When your BAC rises quickly, it can overwhelm your brain’s ability to form memories.
  • Individual factors: Factors like genetics, age, sex, overall health, and previous experiences with alcohol or drugs affect your susceptibility to blackouts. You may be more prone to blackouts than others based on how your body metabolizes substances and your brain’s reaction to the chemicals.

How To Prevent Blackouts

How Blackouts Occur

You may prevent a blackout by employing several strategies focusing on responsible consumption[3]. Here are some ways you can prevent blackouts:

  • Moderate consumption: Limit the amount of alcohol or drugs you use in a single day. Stick to recommended guidelines for safe drinking and avoid binge drinking.
  • Know your body’s limits: Understand your tolerance to alcohol and drugs. Weight and metabolism can affect how substances impact your body and brain.
  • Avoid mixing substances: Combining alcohol with drugs is likely to increase the risk of blackout. Follow the medical advice of professionals when it comes to drinking alcohol or taking drugs while using medications.
  • Stay hydrated: Alcohol and drugs may dehydrate you. This can exacerbate the effects of intoxication. Drink water between and during any alcoholic beverages you consume.
  • ​​Eat: Consuming food both before drinking or taking drugs can slow down their absorption into your bloodstream. This can blunt their impact, providing more of a buffer to blacking out.
  • Avoid shots: Shots may lead to rapid intoxication due to their condensed, high alcohol concentration. Stick to beverages with lower alcohol content and consume them slowly.
  • Plan: Make sure you have a safe way to get home BEFORE you start drinking. Avoid situations where you may drink excessively or engage in risky behaviors.
  • Monitor yourself: Keep track of how many drinks you have or how many drugs you take. Set limits and stick to them.
  • Pace yourself: Alternate alcoholic drinks with glasses of water to your consumption and give your body the time it needs to process the alcohol.
  • Recognize warning signs: Learn to recognize the early signs of intoxication. These signs include slurred speech, impaired coordination, and changes in behavior. If you notice any of these signs, it’s time to slow down or stop drinking.
  • Have a sober friend: Recruit a friend who can help you monitor your drinking and drug use and make sure you don’t take it too far. They can also help you get home safely if you need to.
  • Educate yourself: Research and understand the effects of alcohol and drugs on your body. Knowing the risks will help you make better decisions.
  • Find support: If you are blacking out regularly or struggling with controlling your substance use, it may be time to seek help from a healthcare professional or addiction specialist.

Treatment and Support Is Available

If you find yourself drinking or using drugs to the point of blacking out, it’s time to slow down. Treatment options are available, and support is crucial. Get the help you need from medical professionals who can give you the specialized care and attention you deserve.

Frequently Asked Questions

What Substances Can Cause Blackouts?

Many drugs are known to cause blackouts.[4] Here are some of the most common.

  • Alcohol: Alcohol use directly affects the hippocampus and interferes with your brain’s ability to form new memories. Binge drinking, consuming large amounts of alcohol quickly, and drinking on an empty stomach can greatly increase the likelihood of experiencing an alcohol-induced blackout.
  • Benzodiazepines: Benzodiazepines can cause memory impairment and blackouts. The likelihood of a blackout goes up considerably when a benzodiazepine is taken in higher doses or mixed with alcohol.
  • Barbiturates: Central nervous system depressants like phenobarbital and secobarbital can cause severe sedation and memory impairment. This can lead to blackouts.
  • Gamma-Hydroxybutyric acid: GHB is a central nervous system depressant that can cause blackouts and memory loss, especially when taken in higher doses or combined with heavy drinking.
  • Inhalants: Substances like solvents, aerosols, and gasses can cause blackouts and memory loss when inhaled due to their negative effects on your central nervous system.
  • Cannabis (or THC): While cannabis does not cause blackouts like alcohol or benzodiazepines, high doses of THC can impair short-term memory and lead to poor memory formation during intoxication.

What Are the Potential Ramifications of Blacking Out?

Blacking out can have severe health ramifications.

  • Physical injury: You may engage in risky behaviors while blacked out. Accidents, falls, and other physical harm are risks.
  • Mental health: Repeated blackouts may contribute to mental health issues. The inability to recall actions or events during blackout episodes may also cause distress and guilt.
  • Brain function: Alcohol-related blackouts may lead to impairments in memory and learning over time. The hippocampus is especially vulnerable to damage from alcohol abuse.
  • Alcohol poisoning: The potentially high levels of alcohol consumption that result in blackouts can also result in alcohol poisoning. This is a life-threatening condition that requires immediate medical attention.
  • Social and interpersonal consequences: Blackouts can strain relationships, leading to social isolation and difficulty maintaining personal connections.
  • Legal issues: Engaging in illegal activities during a blackout, like driving under the influence or participating in acts of violence, can result in severe legal consequences.

What Are the Potential Long-Term Ramifications of Blacking Out?

Experiencing repeated blackouts may lead to long-term ramifications that affect physical health and overall well-being. A big concern is the potential for cognitive impairment over time. Chronic alcohol-related blackouts may impact memory and learning abilities. This damage can manifest as difficulties in remembering new information and may contribute to cognitive decline over the later years of life.

Other concerns are informed by the level of alcohol abuse that causes blackouts in the first place. Drinking at this level can lead to all manner of damage and disease, including the development of alcohol use disorder, liver disease, brain damage, cardiovascular problems, and many other ailments.

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[1] National Institute on Alcohol Abuse and Alcoholism. (n.d.). Interrupted memories: Alcohol-induced blackouts. Retrieved June 28, 2024, from

[2] National Center for Biotechnology Information. (2019). The neurobiological consequences of alcohol use and abuse. PubMed Central. Retrieved June 28, 2024, from

[3] Healthline. (n.d.). What causes blackouts and how to prevent them. Retrieved June 28, 2024, from

[4] National Institute on Drug Abuse. (n.d.). Commonly used drugs charts. Retrieved June 28, 2024, from