Alcohol and blackouts
What is a blackout? Some people experience alcohol-related blackouts during or after drinking alcohol. Find out what they are, why this happens and what you can do if you experience one.
What is a blackout?
An alcohol related blackout is a period of memory loss during or after drinking. Unlike passing out, someone experiencing a blackout is still conscious, talking, walking, and interacting with others but later may not remember what happened.
This happens when alcohol disrupts the brain’s memory centre, called the hippocampus.1 Drinking too much, too quickly can prevent the brain from forming new memories, resulting in memory gaps ranging from minutes to hours.2
Why do blackouts happen?3
There are two main types of blackouts:
- En bloc (total blackout): Complete memory loss for events that occurred while intoxicated. These memories cannot be recovered later and these blackouts usually last for hours.
- Fragmentary (partial blackouts): Partial memory loss, where some memories can return if triggered by reminders.
Blackouts occur when blood alcohol concentration (BAC) rises quickly, often after binge drinking or drinking on an empty stomach. Anyone can experience a blackout, regardless of age or drinking experience.
Women may be more vulnerable to blackouts due to generally lower body weight and less water in the body, which means alcohol has a stronger effect.4
Are blackouts dangerous?5
Alcohol blackouts are dangerous as they are linked to high-risk behaviours and serious consequences like:
- Injuries or accidents
- Aggressive or risky behaviour
- Unplanned or unsafe sex
- Getting lost or stranded
- Legal or financial trouble
Frequent blackout may signal heavy episodic drinking which increases the risk of alcohol-related health problems such as liver disease and several types of cancer.6
How to reduce your risk of blacking out
You can lower your risk of blackouts by:
- Avoiding binge drinking – drinking excessive amounts of alcohol in a short space of time
- Sticking to the Chief Medical Officer’s low-risk drinking guidelines of no more than 14 units per week, spread over several days with drink-free days in-between
- Avoiding drinking on an empty stomach
- Pacing yourself by sipping your drink and alternating with water or soft drinks
- Planning how you’ll get home safely
What to do if you've experienced a blackout
If you've had a blackout, it's a sign your drinking may be putting you at risk. You might not remember how you got home, who you were with, or what you said or did. This can all be worrying but there are a number of things you can do:
- Talk to someone you trust about your experience
- Speak to your GP or a health professional if you’re concerned
- Take our Drinking Check below, a quick and confidential tool which requires you to answer up to 10 short questions on your drinking habits and behaviour to understand your level of risk from drinking alcohol.
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Alcohol and hangovers
Support
References
[3] ibid
Last Reviewed: 20th August 2025
Next Review due: 20th August 2028