When a person’s blood alcohol content reaches a certain level, the alcohol prevents their brain from recording long-term memory. Blackouts can lead to more than just hangovers — sexual assault, car crashes and damaged relationships often ensue.

What Happens When You Blackout?

Experiences with alcohol in high school and college include drinking until you pass out (or blacking out) — the universal sign of a fun night of youth. But blackouts due to alcohol are a serious threat to the health and safety of any person. Binge drinking can quickly turn to blackout, and a litany of other dangerous activities can follow, including injury, sexual assault, violence and alcohol poisoning.

The most pervasive symptom of blacking out is memory loss. Those who experience blackouts often have to ask friends what they did during the period of memory loss. Some common responses include:

  • Insulted someone
  • Spent money
  • Engaged in some form of sexual activity
  • Had unprotected sex
  • Had unwanted sex
  • Argued or fought with someone
  • Damaged property

Alcohol blackouts — or any memory blackouts — are especially dangerous to teens because memory loss is not the same as a lack of consciousness. Getting blackout drunk often leaves the user incapacitated and in one place. Those who drink so much they can’t remember last night were still awake and functioning during the period, making them more likely to be the victim of a crime like theft or sexual assault, or more likely to commit a crime, like driving and crashing their car.

For example, the next morning, the drinker could find themselves in jail for a crime they don’t remember committing, or they could end up being the victim of a sexual assault.

What Is a Blackout?

Alcohol blackouts are a form of amnesia, or memory loss, brought on by excessive alcohol consumption. Some refer to alcohol blackouts as alcohol-induced amnesia.

A blackout is a complete, or en bloc, period of amnesia, in which the brain does not form new long-term memories. People who have blacked out cannot remember where they were or what happened to them after they began drinking, and sometimes may even wake up in a strange place or with a strange person.

Partial, or fragmentary, alcohol-induced amnesia — when a person can remember bits and pieces of the time period but not the full experience — is often called a brownout.

What Causes Blackouts When Drinking?

Research shows alcohol can begin affecting a person’s memory after they have had only one or two drinks. The more a person drinks the more alcohol impairs their memory. Blackouts are most closely linked to the drinker’s blood alcohol content. A brownout or a blackout can occur at a BAC of around 0.14% to 0.17% BAC, but it’s considered very likely at .20% BAC.

Factors that impact a person’s BAC include:

  • Gender
  • Weight
  • Genetics
  • Recent food intake
  • Drinking speed
  • Type of alcohol they consume

Medical Disclaimer: The Recovery Village aims to improve the quality of life for people struggling with a substance use or mental health disorder with fact-based content about the nature of behavioral health conditions, treatment options and their related outcomes. We publish material that is researched, cited, edited and reviewed by licensed medical professionals. The information we provide is not intended to be a substitute for professional medical advice, diagnosis or treatment. It should not be used in place of the advice of your physician or other qualified healthcare provider.