What is a blackout?

Blackout is a word used to describe a temporary loss of consciousness. When a person has a blackout, they are not awake or thinking. They do not know what is happening to them.

Blackouts are also called:

• fainting (syncope)
• a collapse
• passing out

Blackouts can be caused by alcohol or drug use. If this happens, you may have memory loss.

If you have a blackout, it may not be serious. But it's still important to see your doctor. They will try and work out what caused the blackouts.

What symptoms are related to blackouts?

If you have a blackout, you lose consciousness for a short time. Before that, you may:

• have blurred vision
• feel confused
• feel dizzy
• look pale
• feel anxious
• be sweaty

You may fall down as you lose consciousness.

What causes a blackout?

There are many different causes of fainting or blackouts, such as:

• a problem with your cardiovascular system
• a problem within your brain
• the effects of drugs or alcohol

What is fainting?

Fainting is a type of blackout. The medical term is syncope. It is when you lose consciousness for a short time. There are many reasons why people faint. Fainting can happen when your heart rate drops and your blood vessels widen. This causes low blood pressure. It can happen when you:

• are very hot
• are distressed
• are in pain
• see or smell something unpleasant
• are coughing
• are going to the toilet

Sometimes, you might faint when you stand up too quickly. This is because your blood pressure suddenly drops.

Some medicines can also trigger blackouts.

Fainting can also be caused by more serious health problems, including:

• arrhythmia (abnormal heart rhythm)
• heart disease
• problems with the blood vessels in your brain
• a seizure (fit)
• low blood sugar

Blackouts caused by alcohol

Sometimes, people lose their memory after drinking a lot of alcohol. They may describe this as a blackout.

If you drink a lot of alcohol, you may not remember what happened. When you sober up, it can be hard to remember things that you did or said. This is because there was too much alcohol in your blood. Your brain can't make new memories when there is too much alcohol in your blood. The more you drink, the more memory you lose.

You are more likely to black out from alcohol if you:

• drink on an empty stomach
• drink too much too quickly

It's a good idea to try and manage how much alcohol you drink. This can lower the chance of you losing your memory for a while. Make sure you:

• drink slowly and don't drink too much
• drink water between alcoholic drinks
• eat food while you are drinking
• avoid binge drinking (drinking a lot in one session)
• think about why you are drinking

Drinking so much that you black out can cause physical, social and mental problems. It can lead to:

• accidents and injuries
• violent behaviour
• long-term health issues
• alcohol poisoning

Sometimes it can be hard to admit you have a problem with alcohol or drugs. A doctor can help you manage all kinds of health problems. If you feel alcohol use is affecting your health or someone in your family, there are resources that can help.

When should I see a doctor?

If you have blacked out and you don't know why, you should go to a doctor. It could be a sign that something is seriously wrong.

This is very important if you also have:

• a family history of fainting
• a family history of heart problems
• chest pain
• heart palpitations

If you see someone blackout, take these steps:

• put their legs above the level of their head
• loosen tight clothing
• make sure the person has fresh air
• give first aid for any injury from a fall
• get medical help

How are blackouts diagnosed?

If you have a blackout, your doctor or hospital medical team will try to find the cause. They may do:

• a physical examination
• blood pressure testing
• blood tests to check your blood sugar level
• an electrocardiogram (ECG) or Holter monitoring of heart rhythm
• an echocardiogram
• an exercise stress test
• tilt table testing

How are blackouts treated?

Treatment will depend on the cause of your blackout.

For example, blackouts caused by cardiac (heart) problems may be treated by a heart specialist. Other treatments may include:

• fluids
• medicines
• advice on lifestyle changes

First aid for blackouts

There are things you can do if you feel like you are going to blackout.

If you feel faint, "go-to-ground". This means you should get as close to the ground as possible. This will help you avoid injury when you black out.

Once you are on the ground, lie down with your feet higher than your head.

If you can, lie down or sit in a cool, quiet space.

Can blackouts be prevented?

Blackouts are caused by different health issues. It is not always possible to prevent them.

You can stop some types of blackout from happening by:

• getting up slowly
• staying hydrated
• eating well
• getting fresh air
• avoiding triggers such as hot showers, and standing or lying down for too long

Complications of blackouts

If you have had a blackout, see a doctor. You are not permitted to drive after some types of blackouts. A doctor will need to review the cause and clear you to drive.

If you blackout, you may also be at risk of injury from falling over.

Resources and Support

Visit the Heart Foundation website to learn about heart health.

If you or someone you know need help with alcohol, visit the Alcoholics Anonymous (AA) Australia website or call 1300 222 222.

For free and confidential advice about alcohol and other drugs, you can also call the National Alcohol and Other Drug hotline: 1800 250 015.

You could contact the Family Drug Support service. The phone number is 1300 368 186.

The Australian Indigenous Alcohol and Other Drugs Knowledge Centre is an online resource. It has information for workers and communities working to reduce the use of alcohol and other drugs in Aboriginal and Torres Strait Islander communities.

The Alcohol and Drug Foundation has helpful resources in other languages.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with 24 hours a day, 7 days a week.