What Causes Shock?

Conditions list medically reviewed by George Krucik, MD, MBA

Your body enters shock when you don’t have enough blood circulating through your system to keep your organs and tissues functioning properly. It can be caused by any injury or condition that affects the flow of blood through your body. Shock can... Read More

Your body enters shock when you don’t have enough blood circulating through your system to keep your organs and tissues functioning properly. It can be caused by any injury or condition that affects the flow of blood through your body. Shock can cause multiple organ failure and lead to life-threatening complications.

There are many types of shock. They fall under four main types, which are based on what has affected the flow of blood. The four major types are:

  • obstructive shock
  • cardiogenic shock
  • distributive shock
  • hypovolemic shock

All forms of shock are life threatening. If you develop symptoms of shock, get medical help immediately.

What are the signs and symptoms of shock?

If you go into shock, you may experience one or more of the following:

  • rapid, weak, or absent pulse
  • irregular heart beat
  • rapid, shallow breathing
  • lightheadedness
  • cool, clammy skin
  • dilated pupils
  • lackluster eyes
  • chest pain
  • nausea
  • confusion
  • anxiety
  • decrease in urine
  • thirst and dry mouth
  • low blood sugar
  • loss of consciousness

What causes shock to occur?

Anything that affects the flow of blood through your body can cause shock. Some causes of shock include:

  • severe allergic reaction
  • significant blood loss
  • heart failure
  • blood infections
  • dehydration
  • poisoning
  • burns

What are the major types of shock?

There are four major types of shock, each of which can be caused by a number of different events.

Obstructive shock

Obstructive shock occurs when blood can’t get where it needs to go. A pulmonary embolism is one condition that may cause an interruption to blood flow. Conditions that can cause a buildup of air or fluid in the chest cavity can also lead to obstructive shock. These include:

  • pneumothorax, or collapsed lung
  • Hemothorax, when blood collects in the space between the chest wall and lung
  • cardiac tamponade, when blood or fluids fill the space between the sac that surrounds the heart and the heart muscle

Cardiogenic shock

Damage to your heart can decrease the blood flow to your body, leading to cardiogenic shock. Common causes of cardiogenic shock include:

  • damage to your heart muscle
  • irregular heart rhythm
  • very slow heart rhythm

Distributive shock

Conditions that cause your blood vessels to lose their tone can cause distributive shock. When your blood vessels lose their tone, they can become so open and floppy that not enough blood pressure supplies your organs. Distributive shock can result in symptoms including:

  • flushing
  • low blood pressure
  • loss of consciousness

Anaphylactic shock is a type of distributive shock. It’s a complication of a severe allergic reaction known as anaphylaxis. Allergic reactions occur when your body mistakenly treats a harmless substance as harmful. This triggers a dangerous immune response. Anaphylaxis is usually caused by allergic reactions to food, insect venom, medications, or latex.

Septic shock is also a form of distributive shock. Sepsis, also known as blood poisoning, is a condition caused by infections that lead to bacteria entering your bloodstream. Septic shock occurs when bacteria and their toxins cause serious damage to tissues or organs in your body.

Drug toxicities and brain injuries can also lead to distributive shock.

Hypovolemic shock

Hypovolemic shock is caused when there isn’t enough blood in your blood vessels to carry oxygen to your organs. This can be caused by severe blood loss, for example, from injuries.

Your blood delivers oxygen and vital nutrients to your organs. If you lose too much blood, your organs can’t function properly. This type of shock can also happen from serious dehydration

How is shock diagnosed?

First responders and doctors often recognize shock by its external symptoms. They may also check for:

  • low blood pressure
  • weak pulse
  • rapid heartbeat

Once they’ve diagnosed shock, their first priority is to provide lifesaving treatment to get blood circulating through your body as quickly as possible. This can be done by giving fluid, drugs, blood products, and supportive care.  It will not resolve unless you can find and treat the cause. 

Once you’re stable, your doctor can try to diagnose the cause of shock. To do so, they may order one or more tests, such as imaging or blood tests.

Imaging tests

Your doctor may order imaging tests to check for injuries or damage to your internal tissues and organs, such as:

  • bone fractures
  • organ ruptures
  • muscle or tendon tears
  • abnormal growths

Such tests include:

Blood tests

Your doctor may use blood tests to look for signs of:

  • significant blood loss
  • infection in your blood
  • drug or medication overdose

How is shock treated?

Shock can lead to unconsciousness, breathing problems, and even cardiac arrest. If you suspect that you’re experiencing shock, get medical help immediately. If you suspect that someone else has gone into shock, call 911 and provide first-aid treatment until professional help arrives.

First aid treatment

If you suspect someone has gone into shock, call 911. Then follow these steps.

If they’re unconscious:

  • Check to see if they’re still breathing and have a heartbeat.
  • If you don’t detect breathing or a heartbeat, begin CPR.

If they’re breathing:

  • Lay them down on their back.
  • Elevate their feet at least 12 inches above the ground. This position, known as the shock position, helps direct blood to their vital organs where it’s most needed.
  • Cover them with a blanket or extra clothing to help keep them warm.
  • Check their breathing and heart rate regularly for changes.

If you suspect they’ve injured their head, neck, or back, avoid moving them.

Apply first aid to any visible wounds. If you suspect they’re experiencing an allergic reaction, ask them if they have an epinephrine auto-injector (EpiPen). People with severe allergies often carry this device.

It contains an easy-to-inject needle with a dose of hormone called epinephrine. You can use it to treat anaphylaxis.

If they begin to vomit, turn their head sideways. This helps prevent choking. If you suspect they’ve injured their neck or back, avoid turning their head. Instead, stabilize their neck and roll their entire body to the side to clear the vomit out.

Medical care

Your doctor’s treatment plan for shock will depend on the cause of your condition. Different types of shock are treated differently. For example, your doctor may use:

  • epinephrine and other drugs to treat anaphylactic shock
  • blood transfusion to replace lost blood and treat hypovolemic shock
  • medications, heart surgery, or other interventions to treat cardiogenic shock
  • antibiotics to treat septic shock

Can you fully recover from shock?

It’s possible to fully recover from shock. But if it isn’t treated quickly enough, shock can lead to permanent organ damage, disability, and even death. It’s critical to call 911 immediately if you suspect that you’re experiencing shock or find someone with symptoms of shock.

Your chances of recovery and long-term outlook depend on many factors, including:

  • the cause of shock
  • the length of time you were in shock
  • the area and extent of organ damage that you sustained
  • the treatment and care that you received
  • your age and medical history

Can shock be prevented?

Some forms and cases of shock are preventable. Take steps to lead a safe and healthy lifestyle. For example:

  • If you’ve been diagnosed with severe allergies, avoid your triggers, carry an epinephrine auto-injector, and use it at the first sign of an anaphylactic reaction.
  • To lower your risk of blood loss from injuries, wear protective gear when taking part in contact sports, riding your bike, using dangerous equipment, and wear a seatbelt when traveling in motor vehicles.
  • To lower your chances of heart damage, eat a well-balanced diet, exercise regularly, and avoid smoking and second-hand smoke.
  • Stay hydrated by drinking plenty of fluids. This is especially important when you’re spending time in very hot or humid environments. 

Medically reviewed by Carissa Stephens, RN, CCRN, CPN on October 21, 2016Written by April Khan


19 possible conditions

This feature is for informational purposes only and should not be used to diagnose. Please consult a healthcare professional if you have health concerns.