An Overview of Shock

Shock is a medical emergency that occurs when the tissues in your body can't get enough blood, oxygen, and nutrients. Loss of consciousness may be the first noticeable effect and shock can worsen rapidly, potentially causing permanent organ damage (such as intestine or brain damage) or death.

There are several causes of shock, including traumatic blood loss and sudden heart failure. Emergency medical professionals can identify shock very quickly, and the condition requires urgent treatment.

The outcome after an episode of shock can vary. Recovery can take months and generally involves rehabilitation.



MERT Deliver Casualties At The Camp Bastion Hospital
Marco Di Lauro / Getty Images

Being severely dehydrated or having an infection or heart failure can make you more prone to shock. But shock can affect anyone at any age.

There are a number of symptoms that occur with shock. Some of them may seem to be contradictory—for example, shock can make a person's heart race, producing a rapid pulse, or it can make the heart rate and pulse slow down.

Some of the signs and symptoms depend on the cause and the stage of shock.

Common symptoms of shock include:

  • Trouble breathing
  • Weak pulse
  • Rapid heart rate, which can later slow down
  • Confusion
  • Loss of consciousness
  • Collapsing
  • Pale, clammy, and/or sweaty skin
  • Cold hands or body

Associated Symptoms

Shock can be accompanied by other signs and symptoms. These signs are not part of the body's shock reaction, but they can help give your medical team an idea about the cause, which helps direct the treatment plan.

  • Fever can occur with sepsis, a severe blood infection
  • Skin redness, rash, and swelling are signs of an anaphylactic (allergic) reaction
  • Pupil dilation (unusually large pupils) is a sign of brain damage
  • Cough can accompany lung failure

Shock is a true medical emergency. If you have any concern that you or someone is could be experiencing shock, call 911 immediately.



Epinephrine injector for allergy.
mario loiselle / Getty Images

Shock is also referred to as hypoperfusion, which is diminished blood flow to the body's tissues and organs. Shock is severely diminished blood flow, and it is caused by major medical events.

Trauma with rapid blood loss can decrease the body's overall blood supply. Major illnesses cause the body to respond in ways that affect blood flow. And acute (sudden) or chronic (long term) cardiovascular (heart and/or blood vessel) problems can prevent blood from traveling through the body as it should.

Common Causes of Shock

Shock can begin suddenly, such as immediately after a serious injury or with anaphylaxis. It can also develop gradually due to a major infection or illness.

Situations that cause shock include:

  • Sepsis
  • Dehydration: Lack of body fluid
  • Hemorrhage: Bleeding within the body or blood loss from the body
  • Anaphylaxis: A major, possibly fatal, allergic reaction
  • Neurogenic problems: Difficulty controlling blood pressure and pulse due to brain and/or spine damage
  • Heart attack: A sudden disruption in the heart function and heartbeat
  • Pericardial tamponade: Physical pressure around the heart muscle
  • Pneumothorax: A collapsed lung

During major physical stress, such as that caused by sepsis, neurological damage, and anaphylaxis, the body cannot maintain normal control over blood pressure and pulse. This is described as hemodynamic instability, and it interferes with blood flow to the tissues.



woman collapsed in fatigue
Macduff Everton / Getty Images

Shock is diagnosed based on a person's symptoms and vital signs. Vital signs are measures of vital functions, such as heart rate, blood pressure, and breathing.

Paramedics can quickly assess the heart rate by checking the pulse and can assess blood pressure based on the intensity of the pulse and a blood pressure reading. Paramedics also assess breathing rate.

If the body is able to maintain normal blood pressure as a shock is developing, it is described as compensated shock. Compensated shock rapidly worsens if untreated. As blood pressure begins to fall, the situation is defined as uncompensated shock. Uncompensated shock can be fatal.

Once you are stabilized, your medical team will determine which type of shock you have. There are four types of shock.


Hypovolemic shock develops when there is a deficient amount of fluid and blood flowing in the blood vessels. This type of shock is usually characterized by a rapid, weak pulse and low blood pressure. Sometimes, hypovolemic shock is associated with pale, cold skin.


Distributive shock usually occurs when blood vessels dilate (widen). Neurogenic shock, sepsis, and anaphylaxis can produce this physical reaction. Distributive shock is characterized by low blood pressure, and possibly redness or swelling of the limbs or any part of the body.


Cardiogenic shock can develop when the heart cannot pump as it should. A heart attack is a sudden event in which heart muscles cannot function. Heart failure, a chronic process, makes it difficult for the heart to pump and predisposes to shock (of any type).

The result of cardiogenic shock is that the body doesn't get the blood that it needs. Your medical team can identify cardiogenic shock by assessing your heart rhythm, pulse, blood pressure, and oxygen levels (such as with a pulse oximeter).


Obstructive shock occurs when the flow of blood is blocked. Certain types of trauma or medical emergencies can physically prevent blood from flowing in the heart and/or blood vessels.

This type of shock is more difficult to diagnose, often involving imaging tests (such as a chest x-ray) or interventional diagnostic tests.

Combinations of Shock Types

A person can have more than one type of shock at a time.

For example, septic shock is an infection that results in dehydration (hypovolemic) and blood vessel dilation (distributive). And trauma to the chest often results in a tension pneumothorax (obstructive) and also in severe bleeding (hypovolemic).



Senior woman holding chest in pain
Science Photo Library / Getty Images

Shock must be treated urgently. Your medical team will likely start treatment in the ambulance if you are being transported to the hospital. If you develop shock while already in the hospital, treatment is initiated right away.

Treatment strategies used during shock include:

  • Intravenous (IV fluids)
  • Maintaining optimal body temperature (warming with a blanket or using medication to lower a fever)
  • Medications to raise blood pressure or slow pulse if necessary
  • Nasal oxygen
  • Support for breathing

You may not need all of these treatments if you develop shock, but your medical team will closely monitor you to be able to start any of these therapies if you need them.

Treating the Cause of Shock

The cause of shock must also be treated medically or surgically. For example, you may need antibiotics to manage an infection. Surgical repair of a wound may be necessary. A blood transfusion may be needed to replace blood lost during extensive bleeding. If you have fluid compressing your lungs, you may need to have thoracentesis an interventional procedure that removes fluid from around the lungs.

A Word From Verywell

Shock is a major medical event. After recovering, from the life-threatening stage, you may have residual effects, such as fatigue, muscle weakness, or weight loss. Often, rehabilitation is necessary to regain strength and optimal function.

Was this page helpful?

Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Shock. MedlinePlus. Oct 8, 2019.

  2. Norrby-Teglund A, Treutiger C-J. Sepsis. Antibiotic and Chemotherapy. 2010:472-482. doi:10.1016/b978-0-7020-4064-1.00038-5

  3. Helmy A, Kirkpatrick PJ, Seeley HM, Corteen E, Menon DK, Hutchinson PJ. Fixed, dilated pupils following traumatic brain injury: historical perspectives, causes and ophthalmological sequelae. Acta Neurochir Suppl. 2012;114:295-9. doi:10.1007/978-3-7091-0956-4_57

  4. Taghavi S, Askari R. Hypovolemic Shock. Treasure Island, Fl: StatPearls Publishing; 2019.

  5. Smith N, Lopez RA, Silberman M. Distributive Shock. Treasure Island, Fl: StatPearls Publishing; 2019.

Additional Reading