Healthdirect Free Australian health advice you can count on.

Medical problem? Call 1800 022 222. If you need urgent medical help, call triple zero immediately

healthdirect Australia is a free service where you can talk to a nurse or doctor who can help you know what to do.

beginning of content

Blackouts

4-minute read

What is a blackout?

A blackout is a temporary loss of consciousness. In a blackout, you experience a loss of memory. There are many different causes of blackout – it might be an effect of drugs or alcohol, a problem with circulation, or a problem within the brain, such as epilepsy.

It may not be serious, but it is important to see your doctor and try to establish the underlying cause.

If you have a blackout, you lose consciousness temporarily. Before that, you might fall down, have blurred-vision, or be confused.

Sometimes, people experience memory loss and describe this as a blackout – for example, after they have drunk a lot of alcohol or taken illicit drugs.

What causes a blackout?

One common cause of a blackout is fainting. Fainting occurs when your heart rate drops and your blood vessels widen, resulting in low blood pressure. It can happen when you are very hot, distressed, in severe pain, you see or smell something unpleasant, or while you are coughing or going to the toilet. Sometimes, you might black out when you stand up too quickly. This is because your blood pressure suddenly drops.

Blacking out can also be caused by a serious health condition, including:

How are blackouts prevented and treated?

Treatment will depend on the cause of your blackout. For example, if it was caused by a heart rhythm problem, there are medicines that may help prevent you from having another one. However, it is not always possible to prevent blackouts.

If you feel faint, lie down or sit with your head between your knees. Make sure you stand up or change position slowly.

If you have had a blackout caused by fainting, try to avoid triggers like standing for too long or getting dehydrated.

Blackouts caused by alcohol

People can black out because they have drunk a lot of alcohol. In this case, the term blackout refers to memory loss. When they sober up, they cannot remember what happened while they were drunk. This is because the brain cannot form new memories when the alcohol in your blood reaches a certain level. The more you drink, the more memory you lose.

Drinking enough to cause a blackout will also cause problems with your walking, talking, standing, judgement and vision.

You are more likely to black out from alcohol if you drink on an empty stomach or if you drink too much too quickly. To avoid blacking out from alcohol, make sure you drink slowly and do not drink too much. Take sips of water between sips of alcohol, and eat food while you drink. Avoid binge drinking.

Drinking so much that you black out can cause physical, social and mental problems. It can lead to accidents and injuries, alcohol poisoning, fights and long-term health issues. If you need help with alcohol, visit:

When should I seek help for a blackout?

If you have blacked out and you do not know why, you should always seek medical attention. It could be a sign that something is seriously wrong, and it is a common cause of injuries, especially in older people.

If you see someone else black out, raise their legs above the level of their head, loosen tight clothing and seek medical attention.

If you are with someone who is unconscious, call triple zero (000) for an ambulance, and if the person stops breathing, start CPR.

Learn more here about the development and quality assurance of healthdirect content.

Last reviewed: January 2021


Back To Top

Need more information?

These trusted information partners have more on this topic.

Top results

Syncope (fainting) - MyDr.com.au

Syncope (fainting or passing out) is a sudden, temporary loss of consciousness. Find out more about the causes, diagnosis and treatment.

Read more on myDr website

Fainting

Fainting is a sudden, usually temporary loss of consciousness often caused by a lack of oxygen to the brain. When a person is unconscious they are unable to respond.

Read more on WA Health website

Fainting

First aid fact sheet

Read more on St John Ambulance Australia website

Fainting - Better Health Channel

betterhealth.vic.gov.au

Read more on Better Health Channel website

:: Events That Arent Epilepsy - Epilepsy Action AustraliaEpilepsy Action Australia ::

Seizures usually involve temporary changes in behaviour and movement

Read more on Epilepsy Action Australia website

Concussion

Any person who has suffered loss of consciousness or an altered state of consciousness after a blow to the head should not return to their activity (eg sport) and should see a medical practitioner urgently.

Read more on St John Ambulance Australia website

:: Managing Epilepsy | Epilepsy Action AustraliaEpilepsy Action Australia ::

Medication is the first line of treatment in the management of epilepsy. With regular medication and a sensible lifestyle a full and active life is possible.

Read more on Epilepsy Action Australia website

Diabetes emergency

First aid fact sheet

Read more on St John Ambulance Australia website

Severe allergic reaction

A severe allergic reaction is called anaphylaxis and is potentially life-threatening.

Read more on St John Ambulance Australia website

Epilepsy - Lab Tests Online AU

Epilepsy is recurring unprovoked seizures or abnormal electrical discharges of the brain that disrupt normal signalling of the brain to the rest of the body.

Read more on Lab Tests Online AU website

Healthdirect 24hr 7 days a week hotline

24 hour health advice you can count on

1800 022 222

Government Accredited with over 140 information partners

We are a government-funded service, providing quality, approved health information and advice

Australian Government, health department logo ACT Government logo New South Wales government, health department logo Northen Territory Government logo Government of South Australia, health department logo Tasmanian government logo Victorian government logo Government of Western Australia, health department logo