Shock is a life-threatening medical emergency that can develop when the body is no longer delivering enough oxygen-rich blood to vital organs such as the brain, heart and kidneys.
It can follow severe bleeding, major burns, serious injury, heart problems, severe allergic reactions, significant fluid loss and other medical emergencies. A person in shock may initially appear pale, anxious or unwell, but their condition can deteriorate quickly.
This guide explains how to recognise the signs of shock, common causes, what first aid to give and when to call 999.
Important: medical shock is not the same as feeling emotionally shocked after a frightening event, and it is also different from an electric shock. Suspected medical shock should always be treated as an emergency.
Medical shock occurs when the body's circulation is unable to provide enough blood and oxygen to vital organs and tissues.
This can happen for several reasons. A person may have lost a large amount of blood, their heart may not be pumping effectively, or their blood vessels may have become abnormally dilated because of a severe allergic reaction or another serious medical condition.
Whatever the underlying cause, untreated shock can lead to organ damage, loss of consciousness and cardiac arrest.
Shock is not an illness by itself. It develops because of another serious injury or medical condition.
Possible causes include:
Shock can sometimes develop even when there is no obvious external injury. Internal bleeding, for example, may cause severe shock without visible blood loss.
The exact symptoms vary depending on the cause and severity, but common warning signs can include:
On darker skin tones, colour changes may be easier to notice on the lips, palms of the hands, soles of the feet or inside the eyelids rather than relying only on facial skin colour.
If you suspect someone is developing shock, treat it as a medical emergency.
| Step | What to do | Why it matters |
|---|---|---|
| 1. Make the area safe | Check for danger before approaching, particularly around traffic, machinery, electricity, fire or hazardous substances. | You should not put yourself or other people at further risk. |
| 2. Treat an obvious cause | Deal with immediately life-threatening problems you can safely manage, such as severe external bleeding. | Shock will continue to worsen if the underlying cause is not controlled where possible. |
| 3. Help them lie down | Help the person lie down. If appropriate and there is no suspected injury preventing it, raise and support their legs. | This can help support blood flow to vital organs. |
| 4. Call 999 or 112 | Tell the ambulance service that you suspect shock and explain the possible cause if known. | Shock requires urgent medical assessment and treatment. |
| 5. Keep them warm | Use a coat or blanket and protect them from cold ground without overheating them. | People in shock can lose body heat more easily. |
| 6. Reassure and monitor | Keep them calm and continue checking their breathing and level of response. | Their condition may deteriorate while emergency help is on the way. |
Shock is a life-threatening condition. If you believe someone may be in shock, call 999 or 112 for emergency medical help.
Tell the call handler:
Follow the ambulance call handler's instructions while waiting for help to arrive.
Our How to Call Emergency Services in the Workplace guide explains what information can be useful during an emergency call.
Current first aid guidance commonly recommends helping a person with shock to lie down and, where appropriate, raising and supporting their legs.
However, this should not be done blindly in every situation.
Keep the legs down if raising them would cause pain or if you suspect an injury to the:
If there has been major trauma, a fall, crush incident or another mechanism that could have caused serious injury, avoid unnecessary movement and follow instructions from the emergency services.
No. Do not give a person who is in shock anything to eat or drink while waiting for emergency medical help.
They may become less responsive, vomit or require urgent treatment when the ambulance arrives.
You can reassure them and, if necessary, moisten their lips without giving them a drink.
Yes. Protect them from becoming cold.
If available, place a blanket or other insulating material beneath them if they are lying on cold ground and cover them with a coat or blanket.
Do not use intense direct heat such as a hot-water bottle or heat lamp. The aim is to prevent heat loss and keep them comfortable rather than actively overheating them.
Major blood loss is one of the most important causes of shock.
Bleeding may be external and obvious, or it may occur internally where it cannot be seen. Serious internal bleeding can follow major trauma, falls, crush injuries or other significant injuries.
If there is severe external bleeding, controlling it is an immediate priority while emergency help is being arranged.
For step-by-step guidance, see our First Aid for Major Bleeding guide.
Yes. A person can lose a dangerous amount of blood internally without any visible external bleeding.
Possible warning signs after a serious injury can include:
You cannot control serious internal bleeding with ordinary first aid. Call 999 and keep monitoring the casualty while waiting for emergency medical help.
Major burns can result in significant fluid loss and may lead to shock.
The burn itself should be treated appropriately while emergency assistance is arranged where required. During cooling, take care to keep the casualty warm overall because large burns and prolonged cooling can contribute to hypothermia.
See our Burns and Scalds First Aid guide for detailed guidance.
A severe allergic reaction can cause a dangerous form of shock known as anaphylactic shock.
Signs of anaphylaxis can include:
Anaphylaxis is a medical emergency. Call 999 and use the person's prescribed adrenaline auto-injector if available, following their emergency plan and the device instructions.
For further information, see our First Aid for Allergic Reactions and Anaphylaxis guide.
Serious heart problems can prevent the heart from pumping enough blood around the body and may result in shock.
If someone has chest pain, pressure or discomfort, becomes pale or clammy, feels weak or breathless, or you suspect a heart attack, call 999 immediately.
See our First Aid for Chest Pain and Suspected Heart Attack guide.
Serious crush injuries can cause major tissue damage, internal bleeding and shock.
Do not put yourself in danger attempting to move machinery, vehicles or unstable objects. Call the emergency services and follow their instructions.
Our First Aid for Crush Injuries guide explains this type of emergency in more detail.
A person in severe shock may become unresponsive.
If this happens, check their airway and breathing.
If they are unresponsive but breathing normally, place them in the recovery position if it is safe and appropriate to move them, and continue monitoring their breathing.
If they are not breathing normally, call 999 or have someone call, obtain an AED if available and begin CPR immediately.
See our First Aid for an Unconscious Person and CPR Explained guides for further information.
The word “shock” is also commonly used when someone feels frightened, distressed or overwhelmed after a difficult event.
That emotional response is different from medical shock.
| Medical shock | Emotional shock |
|---|---|
| A life-threatening failure of circulation affecting oxygen delivery to vital organs. | An emotional or psychological response to a frightening or distressing event. |
| May follow severe bleeding, burns, heart problems, anaphylaxis, trauma or serious illness. | May follow bad news, an accident, frightening experience or traumatic event. |
| Requires urgent medical help. | Usually requires reassurance and emotional support, although medical assessment may still be needed depending on what happened. |
If a person has been involved in a significant accident or injury, do not assume symptoms such as pallor, dizziness, rapid breathing or confusion are simply caused by emotional distress.
No.
An electric shock occurs when electrical current passes through the body. It can cause burns, abnormal heart rhythms, cardiac arrest and other serious injuries.
A severe electrical injury could potentially result in medical shock, but the two terms describe different things.
If someone has received a significant electric shock, make sure the electrical source is isolated before approaching and seek emergency medical help where appropriate.
See our First Aid for Electric Shock guide.
When someone appears seriously unwell after an injury or medical emergency, common mistakes include:
Yes. Shock does not always happen immediately.
Someone may initially be awake and talking normally after an accident before gradually becoming pale, weak, restless or confused.
This is one reason it is important to continue monitoring anyone who has experienced:
A deterioration in their condition should be treated seriously.
Yes. Babies and children can develop shock following serious injury, blood or fluid loss, severe allergic reactions and other medical emergencies.
Children may compensate for circulatory problems for a period before deteriorating quickly, so serious symptoms should not be ignored.
If a baby or child appears seriously unwell, becomes unusually sleepy, pale or mottled, has difficulty breathing, becomes less responsive or has suffered a major injury, seek emergency medical help.
A first aid kit cannot reverse the underlying medical causes of shock.
However, appropriate first aid equipment can help manage some causes or associated injuries while emergency services are on the way. For example, dressings and bandages may be used to help control bleeding.
The most important parts of managing suspected shock are:
You can view our range of first aid kits for home, workplace, travel and other environments.
| Check | What to do |
|---|---|
| Danger | Make sure it is safe to approach. |
| Underlying cause | Treat an immediately life-threatening problem you can safely manage, particularly severe bleeding. |
| Position | Help them lie down. Raise and support the legs only where appropriate and where injury does not prevent this. |
| Emergency help | Call 999 or 112 and say that you suspect shock. |
| Warmth | Protect them from the cold using a coat, blanket or similar covering. |
| Food and drink | Do not give them anything to eat or drink. |
| Monitoring | Continue checking breathing and responsiveness until emergency help arrives. |
| Deterioration | If they become unresponsive, reassess breathing and be prepared to use the recovery position or begin CPR as appropriate. |
St John Ambulance provides clinically reviewed UK first aid guidance on recognising and treating shock. It describes shock as a life-threatening condition caused by inadequate oxygen supply to the brain and vital organs.
You can read the St John Ambulance guidance on shock for further information.
Shock is a medical emergency, not simply a feeling of distress after an accident.
It can develop following severe bleeding, burns, serious injury, anaphylaxis, heart problems and several other conditions. Recognising the warning signs early and calling 999 promptly can be critical.
The first aid priorities are to manage an obvious life-threatening cause where possible, help the casualty lie down, call emergency services, prevent them becoming cold and continue monitoring their breathing and responsiveness until professional help arrives.
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