Alcohol Blackout: Causes, Signs, and Risks

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What you will learn

• Alcohol blackouts are temporary losses of memories that happen if you drink too much alcohol.
• Often confused with passing out, alcoholic blackouts don’t involve losing consciousness.
• Alcohol impairs your brain’s ability to form or store memories, leading to gaps in your memory when you’re sober.
• There are risks to blacking out, such as engaging in risky behaviors like driving.
• Blacking out from drinking isn't indicative of addiction on its own, but it can be a sign of concerning alcohol use.

Alcohol “blackouts,” or temporary losses of memory, can occur if you drink too much alcohol. Drinking to the point of a blackout has gained pop culture notoriety, and it may even be a rite of passage for young people, but there are significant risks to consider.

What Is an Alcohol Blackout?

An alcohol-induced blackout is a “gap” in your memory for events that occurred while you were intoxicated.[1] Some people think a “blackout” is when you pass out from drinking, but that’s a temporary loss of consciousness.

Alcohol-related blackouts involve losing your memory while still being conscious. You can still interact with others and move around – possibly even seeming fine to everyone – but you can’t remember what happened the next day.

Blackouts happen when you drink a lot of alcohol to the point of impairing the way your brain transfers memories from short- to long-term memory.[2]

There are two different types of blackouts: a fragmentary blackout, also known as a “gray-out” or “brownout,” which causes gaps in your memory with some recollection of events, and a total blackout, which involves no recollection of events because the memories never formed – or you can’t access them.[3] This type of blackout, an “en bloc” blackout, can cause amnesia that lasts several hours.

It’s possible to progress from blacking out to passing out. If you lose consciousness from drinking alcohol, it can be a sign of an alcohol overdose and requires medical attention.

Signs and Symptoms of an Alcohol-Induced Blackout

It can be difficult to identify a blackout because people can still engage in complex behaviors, including conversing, driving a car, spending money, or having sex. They just don’t remember the behaviors the next day because their memories are not transferred into their brain’s long-term storage of memories.

Alcoholic blackout symptoms can be similar to the symptoms of intoxication and may include:[4]

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

What Causes Blackouts?

Blackouts are typically associated with binge drinking, but they can happen if you combine alcohol with depressants, such as benzodiazepines or opioids and alcohol.

Binge drinking occurs when a man has 5 or more drinks or a woman has 4 or more drinks in 2 hours.[5] It can also refer to a pattern of drinking that increases your blood alcohol concentration (BAC) to 0.08g/dl or more. blackouts often happen when your BAC is 0.16% or higher, usually from excessive drinking in a short time, overwhelming the body’s ability to process alcohol efficiently.[6] Drinking so much so quickly causes a rapid increase in your blood alcohol levels, which can increase the risk of experiencing a blackout.

Understanding the Body During a Blackout

The technical term for a blackout is anterograde amnesia, when you can’t form or store new memories. The mechanism behind blackouts isn’t well understood, but it’s connected to the hippocampus, the area of the brain responsible for memory, and its inability to function properly.[7]

Researchers believe that alcohol alters the way receptors in the brain function, affecting neurotransmitter systems like GABA and glutamate. This impairs the hippocampus and disrupts memory formation. It can weaken the connection between brain cells and impact learning and memory.

If you combine certain drugs with alcohol, such as marijuana, z-drugs used for insomnia like Ambien, or benzodiazepines like Xanax, it can increase the risk of memory loss and blackouts.[8]

Dangers of Excessive Drinking and Blackouts

If you misuse alcohol by binge drinking or excessive drinking, there are many risks. The short-term effects of alcohol misuse include:[9]

• Alcohol poisoning
• Accidents
• Injuries
• Violent actions
• Unprotected sex

Alcohol misuse over long periods can cause adverse health effects, such as:[10]

• Liver damage
• Heart disease
• Stroke
• Pancreatitis
• Certain types of cancer, including liver cancer or bowel cancer

Who Is at Risk of Blacking Out from Alcohol?

Anyone can experience an alcohol-related blackout if their BAC reaches 0.16%. However, blackouts can occur at lower blood alcohol concentration (BAC) levels if you mix alcohol with other drugs. Blackouts are most likely to occur when your BAC rises rapidly. Binge drinking or drinking on an empty stomach can cause a rapid rise in BAC.[11]

Women tend to reach a higher BAC faster than men, mostly due to their smaller body mass. However, people who binge drink are at a high risk for blackouts.[12] Often, binge drinking is prevalent among young adults, such as teens or college students, and may leave them most at risk for blackouts.

Does Blacking Out Mean You Have an Alcohol Addiction?

Blacking out from drinking alcohol doesn’t necessarily mean you have an alcohol use disorder – the official term for alcohol addiction – but it can be a sign of dangerous drinking habits. If you experience blackouts, you may want to consult with your doctor or therapist about your drinking.

Alcohol use disorder, as defined by the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), has the following criteria:[13]

• Taking alcohol in large amounts or over a longer period than intended
• A persistent desire or unsuccessful attempts to cut down or control alcohol
• Spending a great deal of time obtaining, using, or recovering from excessive alcohol use
• Craving more alcohol
• Failing to fulfill major role obligations at work, school, or home from excessive alcohol use
• Continuing alcohol consumption despite having persistent or recurrent social or interpersonal problems caused by alcohol
• Giving up important social, occupational, or recreational activities because of heavy drinking habits
• Using alcohol in situations in which it is physically hazardous
• Continuing alcohol use despite knowledge of having physical or psychological problems

How to Avoid Alcohol-Induced Blackouts

If you want to reduce the risk of blacking out, only drink in moderation, avoid mixing alcohol with other drugs, or avoid drinking completely. Here are some tips to ensure you’re drinking alcohol responsibly:

• Set a limit for your alcohol consumption. Understand the standard drink: a 12-ounce beer, a 5-ounce glass of wine, or a drink with one shot of liquor.[14]
• Count your drinks to avoid overconsuming in a short period.
• Eat food to avoid drinking on an empty stomach.
• Enlist the help of friends or family members to limit your drinking.
• Control your triggers, which are the people, places, and events that may lead to you drinking more than usual. Make a plan in advance to mitigate them before they occur.

Avoid Blackout Drinking

If you’re experiencing blackouts or are concerned about your alcohol use, it’s best to get an evaluation. Alcohol use that leads to blackouts – or an alcohol addiction – can have devastating effects on your health and well-being. The sooner you get help, the less likely you will experience adverse effects.