Blackouts

Overview

A blackout means you suddenly and briefly lose consciousness — you pass out or 'go blank' for a short time, then come round. Doctors call this transient loss of consciousness. It is not the same as feeling dizzy, being very tired, or falling asleep. Blackouts can look different from person to person: some people slide to the floor, some go stiff or jerk briefly, and some simply slump in a chair. Because blackouts have many possible causes — from harmless fainting to heart or brain problems — it is always worth getting checked.

Yes, very common. Many people faint at least once in their life, often as a teenager or in a hot, crowded place. Other causes of blackouts are much less common, which is exactly why a check-up is worth doing.

Anyone can have a blackout. Simple fainting is especially common in teenagers and young adults. In older adults, blackouts often happen when standing up, or are linked to medicines or heart rhythm changes. Seizures can start at any age, and heart rhythm problems that cause blackouts become more common from midlife onwards.

Symptoms

Common symptoms

• Suddenly losing consciousness for a few seconds up to a minute or two
• Going pale, feeling hot or clammy, and feeling light-headed just before
• Nausea, blurred or tunnel vision, or ringing in the ears before you go down
• Brief jerking or stiffening of the arms and legs — this can happen with ordinary fainting too
• Coming round quickly, but feeling washed out, sweaty or shaky
• Feeling confused for a short time afterwards
• Falling or slumping, sometimes causing an injury

Symptoms in children

• Young children may hold their breath and go pale, blue or limp when upset or hurt — frightening to watch but usually harmless
• Teenagers often faint when standing for a long time, in hot rooms, or after skipping meals
• Some children have brief staring spells or jerking movements that need checking for seizures
• Children often don't remember the event, so what a parent or teacher saw is really useful for the doctor

Symptoms in older adults

• A blackout may be put down to 'a fall' — it is worth asking whether they actually lost consciousness
• Standing up can drop blood pressure and cause a blackout, especially with several medicines
• Heart rhythm problems become more common with age
• Confusion or memory gaps afterwards may last longer
• Injuries from falls are more likely, so early checking matters

Causes

Main causes

• Simple fainting (vasovagal syncope) — a reflex that briefly slows the heart and lowers blood pressure, often triggered by heat, pain, standing a long time, or the sight of blood
• Low blood pressure when standing up (orthostatic hypotension)
• Heart rhythm problems, where the heart briefly beats too fast, too slow or unevenly
• Other heart problems, such as a narrowed valve or a weakened heart muscle
• Seizures (epilepsy) — a short burst of unusual electrical activity in the brain
• Low blood sugar, usually in people who take insulin or certain diabetes medicines
• Dehydration, heavy alcohol use, or side effects from medicines that lower blood pressure
• Reflex blackouts triggered by coughing, straining, or passing urine
• Less often, stress-related or psychological attacks that look like blackouts
• Rarely, bleeding around the brain or another serious cause

Risk factors

• Being dehydrated or skipping meals
• Hot, crowded places, or standing still for a long time
• Pregnancy
• Older age, especially when taking several medicines
• Known heart disease, or a family history of heart problems or early sudden death
• Diabetes treated with insulin or tablets that can cause low blood sugar
• Heavy or binge drinking
• Having fainted before
• Medicines that lower blood pressure

When to see a doctor

See a doctor urgently if:

• You have had a blackout for the first time
• You have blacked out while sitting or lying down
• You had a racing or pounding heartbeat, or chest discomfort, around the time of the blackout
• You have had several blackouts recently
• You hurt yourself when you blacked out
• Someone in your family died suddenly and unexpectedly before age 40
• You are pregnant and have blacked out

Book a routine appointment if:

• You have blacked out before and your doctor already checked it, but you want advice on triggers
• You often feel light-headed when standing up
• You want to talk about driving, work or sports safety after a blackout
• You feel anxious about having another blackout
• You would like a review of your medicines
• You want to know what to do if it happens again

Diagnosis

Your doctor will start by listening to your story in detail: what you were doing beforehand, any warning signs, what other people saw, and how quickly you came round. A description from someone who was there is extremely valuable, so bring them along if you can. The doctor will check your pulse, blood pressure lying and standing, and your heart, and will usually arrange a heart tracing (ECG). Which further tests you need depends on what the story suggests.

Tests that may be done

• An ECG — a quick, painless tracing of your heart's electrical activity
• Blood pressure measured lying down and again after standing
• Blood tests to check blood sugar, salts and blood count
• A heart monitor worn at home for a day or more, to catch an irregular rhythm
• A tilt-table test, where you lie on a bed that tilts upright while your heart rate and blood pressure are watched
• An EEG, which records brain wave patterns, if seizures are suspected
• An ultrasound scan of the heart (echocardiogram)
• A brain scan, used only in certain cases
• A short phone video of an episode, if it can be filmed safely, which can really help specialists

What to expect at your appointment

You may not get a diagnosis on the first visit. That is normal — blackouts can be tricky to pin down, and tests are chosen carefully. Keep a simple diary of any further episodes, note your medicines, and ask your doctor whether you should avoid driving in the meantime. Most people get a clear answer within a few weeks.

Treatment

Treatment depends entirely on the cause. For most people with simple fainting, no medicine is needed — understanding your triggers and learning what to do when you feel faint is often enough. If a heart rhythm problem or seizures are found, a specialist team will talk through the options with you and agree a plan together.

Self-care at home

• If you feel faint, sit or lie down straight away and raise your legs — this often stops a blackout
• Cross your legs and clench your fists and thigh muscles to push blood back towards your heart
• Drink enough water and eat regular meals — don't skip breakfast
• Stand up slowly, especially after lying down, after a hot bath, or after a long sit
• Loosen tight clothing and move to a cooler place if you feel faint
• Avoid standing still for long periods — shift your weight or walk on the spot
• Keep a simple diary of episodes: what you were doing, warning signs, and how long it took to recover
• Go easy on alcohol and keep hydrated in hot weather
• Do not drive until you have been assessed — ask your doctor about the rules where you live

Medical treatments

Doctors treat the cause, not just the blackout. For simple fainting, advice on fluids, triggers and recognising warning signs is usually the main approach, and some people are advised to take in a little more salt. If you take medicines that lower blood pressure, your doctor may adjust or change them — never stop or change a medicine yourself. For a heart rhythm problem, a heart specialist may suggest a procedure or a small implanted device. For seizures, a neurologist may prescribe anti-seizure medicine and review it regularly. Stress-related blackouts are helped with talking therapies and breathing or relaxation techniques.

When is surgery considered?

Most people with blackouts never need surgery. A procedure may be discussed if a heart problem is found — for example, a narrowed valve, or a rhythm problem that can be helped with a small implanted device. A heart specialist will explain the benefits and risks clearly. A small number of people whose seizures do not respond to medicine may be assessed by a specialist epilepsy team for surgery.

Living with this condition

Life with blackouts is mostly about knowing your triggers, planning a little, and knowing exactly what to do if you feel one coming on. Tell the people you live and work with what helps you, and what to do if you pass out. Many people find that simple changes — eating breakfast, drinking more water, not standing still for ages — make episodes much rarer.

Lifestyle tips

• Keep regular meals, sleep and fluid intake
• Avoid very hot, crowded places when you can, and take breaks outside
• Rise slowly from bed or a chair, and sit on the edge of the bed for a moment first
• Be careful in the bath or shower — warm water and standing can trigger fainting
• Avoid binge drinking
• Follow the driving advice you are given — it is there to keep you and others safe
• Wear a medical alert item if your doctor suggests it
• Carry a phone and let someone know where you are going if you have frequent episodes

Diet and exercise

Regular meals, enough fluids and steady blood sugar help prevent blackouts. Some people are advised to add a little more salt to their diet — only do this if your doctor suggests it, because salt is not right for everyone, especially with high blood pressure. Exercise is good for you and for your heart; just warm up and cool down, drink water, and avoid sudden hard effort in heat if that has triggered fainting before.

Mental health and emotional wellbeing

It is very common to feel anxious or shaken after a blackout, and some people start avoiding places or activities they used to enjoy. That is understandable, and it is worth talking about. If worry, low mood or panic is building up, tell your doctor — talking therapies can help a lot. If you ever have thoughts of harming yourself, contact your local emergency number or a local crisis line straight away, or reach out to someone you trust and ask them to stay with you.

Prevention

Some blackouts can be prevented and some can't, but a lot can be done to lower the chances. Staying hydrated, eating regularly, standing up slowly and recognising early warning signs prevents many fainting episodes. Keeping heart and blood pressure checks up to date helps catch other causes early.

Screening programmes

There is no national screening programme for blackouts. However, if you have a family history of early sudden death or a known heart condition, tell your doctor — they may suggest a heart check. Regular blood pressure checks and medicine reviews are especially useful as you get older.

Complications

If left untreated

• Injury from falls, such as fractures or head injury
• Road traffic accidents if a blackout happens while driving
• Injury or drowning if a blackout happens while swimming, bathing or using machinery
• A heart rhythm problem going unnoticed and untreated
• Very long or repeated seizures, which need urgent treatment
• Growing anxiety and avoidance of normal activities

Long-term outlook

The outlook is good for most people. Simple fainting rarely causes lasting harm and often becomes less frequent with small lifestyle changes. When another cause is found — a heart rhythm problem or seizures, for example — treatment today is effective and specialist teams are used to managing it. Getting checked early is the single most helpful thing you can do.

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