Blackout Drunk: Signs, Causes & Dangers of Blackout Drinking

Published On: July 26, 2022

‘Blacking out’ from alcohol is a form of memory loss, caused by the excessive amount of alcohol consumed. This can happen to anyone, at any age, as it has happened to at least 50% of the population. [1]

This can be a very confusing and scary experience, as not remembering situations often leads to anxiety about what could have happened and about what actually happened.

Educating yourself about the causes and dangers of blackouts can help you avoid them and the negative consequences attached.

Alcohol-induced blackouts were defined by the NIAAA (National Institute on Alcohol Abuse and Alcoholism). They stated that these blackouts are ‘gaps’ in our memory of events that happened whilst we are heavily intoxicated. [2]

Blacking out is a temporary impairment; the brain cannot transfer short- or long-term memories.

This is not the same as ‘passing out’ from alcohol. This is called ‘syncope’, which is a temporary loss of voluntary movement and consciousness.

During a blackout people are both awake and conscious, but they will not be able to remember what they are doing. You can be talking to people, dancing, fighting, and often seem as though you are just very drunk.

There are two types of blackouts:

  1. Fragmentary blackout (also called a ‘greyout’ or ‘brownout’): people suffer from gaps in their memory of the events, but can recall some interactions or instances.
  2. Total blackout (‘en bloc blackout’): people have no recollection of events as the memories of what occurred have not formed. The time period of this amnesia is different for everyone, which can last for hours.

Despite the difference between passing out and blacking out, blackouts can lead to passing out. Passing out is a sign of alcohol poisoning, drinking too much to the extent that your mind and body cannot cope at that moment.

What is ‘Normal’ Alcohol Consumption?


We should all keep an eye on how much alcohol we consume. It is difficult to know how much alcohol we are drinking unless we calculate every sip of beer or wine we have after a long day. If you are experiencing blacking out after nights out or social events, it can be helpful to know what the usual alcohol limit is.

An alcohol unit is a way to express the amount of pure alcohol that is in every drink. 1 unit is around 10mls or 8g of pure alcohol.

This is the amount of alcohol that an adult can fully process in 1 hour, so after an hour there should be little to no traces of alcohol left in the blood.

To keep control of health risks associated with alcohol, the NHS advises that: [3]

  • Men and women should try to limit their units to 14 a week
  • These drinks are to be spread over at least 3 days, not all in 1 day

For example:

  • A single shot of 40% spirit is 1 unit
  • A small glass of 12% wine is 1.5 units
  • A large glass of 12% wine is 3 units
  • A bottle of 5% beer or cider is 1.7 units, whilst a pint is 2 units

The Centre for Disease Control and Prevention (CDC) states the definition of binge drinking. When a man or woman consumes more than 5 drinks in 2 hours, their blood alcohol content is over 0.008g/dl. [5]

Once the blood alcohol content is over 0.16%, blackouts are likely to occur, specifically when people drink too much too quickly as the body cannot process it fast enough.

Signs and Symptoms of Blacking Out

black out 2

The signs and symptoms of blacking out are difficult to identify, and will often only be recognised after the event. Sometimes people are not aware that they are blacking out until someone discusses something that happened at an event that they cannot remember.

Those that blackout are likely to engage in behaviours or conversations that would not have happened when they were sober.

For example, it is likely that they will have unsocial discussions, unprotected sex, or be violent. This is also likely to happen when someone mixes medication with alcohol.

The symptoms of blacking out are parallel to binge drinking and intoxication:

  • Nausea
  • Headaches and dizziness
  • Muscle spasms
  • Blurred vision and speech difficulty

Causes of Blacking Out

teen drink 2

‘Anterograde amnesia’ is the technical term for blacking out. This experience of memory loss means that new memories are unable to form and therefore you cannot store or revisit them.

The hippocampus is the area of the brain responsible for memory, so when we experience a blackout, it is because this area of the brain can no longer function properly. [6] [7]

Alcohol changes the chemical balance in the brain, inhibiting critical receptors. When these receptors in the brain are compromised, steroid production ceases. Brain cells then cannot connect properly which impacts our memory.

Dangers of Excessive Alcohol Intake

black out 4

Many people who binge drink do so for social or celebrative occasions and do not suffer from an alcohol use disorder. However, blacking out can be a dangerous sign of binge drinking, one of many harmful side effects.

The Center for Disease Control and Prevention states that binge drinking is most common in the younger adult generation, from ages 18 to 34. This is almost twice as common for men than it is for women. [8]

The short-term risks of drinking:

  • Injuries and bruises
  • Falling over and accidents
  • Violence and assault
  • Alcohol poisoning
  • Risky sexual behaviours
  • Blackouts
  • Socially unacceptable behaviour
  • ‘Hangxiety’ (anxiety when you wake up)

The long-term risks of drinking:

  • High blood pressure leading to heart attacks, heart disease, liver disease, and stomach issues.
  • Cancer
  • A weakened immune system, reduces the likelihood of swift recovery
  • Long-term memory issues, including dementia
  • Learning difficulties
  • Mental health disorders such as anxiety and depression
  • Social issues such as family bonds, or responsibilities
  • Addiction and dependency

Self-Help Assessments for Alcoholism

teen drink 3

It is helpful to know whether the amount you drink is considered a ‘problem’. One way to deepen your understanding of alcohol abuse is through self-help questionnaires, used by doctors and hospitals across the world.

The CAGE questionnaire is a short version of this type of questionnaire: [9]

CAGE Questions for Alcohol Use

  1. Have you ever felt you should CUT down your drinking? YES/NO
  2. Have people ever ANNOYED you by critiquing your drinking? YES/NO
  3. Have you ever felt bad or GUILTY about your drinking? YES/NO
  4. Have you ever had a drink first thing in the morning to steady nerves or in order to get rid of a hangover? YES/NO

CAGE Questions Adapted to Include Drug Use (CAGE-AID)

  1. Have you ever felt you ought to cut down on your drinking or drug use? YES/NO
  2. Have people annoyed you by criticizing your drinking or drug use? YES/NO
  3. Have you felt bad or guilty about your drinking or drug use? YES/NO
  4. Have you ever had a drink or used drugs first thing in the morning to steady your nerves or to get rid of a hangover (eye-opener)? YES/NO

If you answer YES to 2 or more questions per 4 questions, then you are displaying signs of alcohol abuse.

Cutting Down and Blackout Prevention


Abstinence from alcohol can be difficult in social situations, so think about drinking in moderation and at a slow pace. Avoid binge drinking (5 or more drinks in a 2-hour period), and be wary about how quickly your body can cope with what you are consuming.

If you are getting drunk quickly, try and make your drinks weaker (eg. by adding more mixers) and eat a heavy meal at least 30-60 minutes before you start drinking. Make sure you sip your drink rather than gulp or ‘down’ it, as this can help you process the alcohol properly and keep on top of how drunk you are.

It may be useful to drink water between drinks. If you struggle in social settings and often use drinking to relax or as a conversation filler, try to limit how much you consume.

Drink cooling beverages such as water, fizzy drinks, or soda, to slow the heart rate and calm you down. For example, if you drink beer, you can add lemonade to make it a shandy. This will last longer and limit how much alcohol you are consuming if you tend to drink quickly.

Try and change your relationship with alcohol. Whether you are getting blackout drunk purposely or by accident, there is a reason it keeps happening.

If you see alcohol as an escape or an excuse for behaviour in certain manners, then this may indicate an alcohol disorder. Self-medicating using alcohol leads to experiences such as blacking out or passing out, and this may lead to both mental and physical complications.

To change your relationship with alcohol, try to:

  • Discover your current tolerance level, and compare it to the standard medical guides
  • Opt for alternative drinks and beverages instead of alcohol or between drinks. Sometimes we drink because we feel the need to in a situation, so swap it for something that will help us sober up.
  • Consider what you want your relationship with alcohol to be. Discussing how you feel before, during, and after you drink with a professional will help this. This can help you set goals and boundaries to control the urges or habits you have developed.
  • Be kind and forgive yourself. Nobody is perfect, and everyone is likely to have taken it too far with alcohol at least once in their life. That being said, try to consider how your drinking habits are affecting you and others around you.

Heavy drinking can often lead to an alcohol use disorder. When people binge drinks their blood alcohol level is too high, leading to alcohol-induced blackouts. Blood alcohol concentrations are so high they cannot be processed, leading to memory loss.

This loss of memory and heavy alcohol consumption can cause brain damage (hippocampal damage). Both fragmentary blackouts and total blackouts cause similar health issues and risk factors.

Excessive alcohol consumption and excessive drinking can have a detrimental effect over a period of time. The warning signs for alcohol addiction start with your relationship with alcohol, the quantities of alcohol involved, and the reason behind the behaviour of heavy drinkers.

Medical conditions such as liver damage, liver cirrhosis, breast cancer, and bowel cancer are all more likely to develop once people start blacking out on a regular basis.

The impact of alcohol is vast, producing both short- and long-term effects. If you are blacking out or believe your relationship with alcohol is not what it should be, don’t hesitate to contact us for more information and help.


[1] Wetherill, R. R., & Fromme, K. (2016). Alcohol-induced blackouts: a review of recent clinical research with practical implications and recommendations for future studiesAlcoholism, clinical and experimental research40(5), 922–935.

[2] National Institute on Alcohol Abuse and Alcoholism. (2021, March). Interrupted Memories: Alcohol-Induced Blackouts.


[4] White, A. (2003). What happened? Alcohol, memory blackouts, and the brainAlcohol Research & Health, 27(2), 186-96.

[5] Centers for Disease Control and Prevention. (2019, December 30). Binge drinking.

[6] Sorumski, C. (2018, October 26). What causes alcohol-induced blackouts?

[7] Dryden, J. (2011, July 6). The biology behind alcohol-induced blackouts.



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