Septic shock can be caused by an infection in any part of the body that is left untreated.

The infection will first cause a response from the body known as sepsis.

Bacterial infections are the most common cause of sepsis. Fungi, such as candida, and viruses can also sometimes lead to sepsis, although this is rare.

Bacterial infections occur if harmful bacteria enter the blood through the skin – for example, when an intravenous drip or catheter has been inserted. Sepsis can also happen after an infection in one of the organs – for example, a urinary tract infection or lung infection.

Read more information about the causes of sepsis.

How septic shock develops

If left untreated, the toxins produced by bacteria can severely damage the body’s cells. They attack the walls of the small blood vessels, causing them to leak fluid from the blood into the surrounding tissues. It can also decrease the heart’s ability to pump blood to the organs. This is called acute circulatory failure, or shock. It significantly lowers your blood pressure.

The fall in blood pressure means the heart cannot supply the body’s vital organs with oxygen-rich blood. Without an oxygen-rich blood supply, the brain, heart, kidneys and liver cannot function properly.

The fall in blood pressure, which does not respond to treatment with fluids, is what distinguishes septic shock from severe sepsis.

Risk factors

Certain groups of people are more at risk of developing septic shock. This is because their immune systems are weaker, which reduces their ability to fight serious infections.

People who are particularly at risk of developing septic shock include:

• newborn babies
• elderly people
• pregnant women
• people with long-term health conditions such as diabetes, cirrhosis or kidney failure
• people with lowered immune systems, such as people with HIV or AIDS or people receiving chemotherapy

Septic shock is a life-threatening condition that happens when your blood pressure drops to a dangerously low level after an infection.

The infection will first cause a response from the body known as sepsis (see the box on this page). If sepsis is not treated, it can lead to severe sepsis and septic shock. 

Read more about the causes of septic shock.

Symptoms of septic shock

Symptoms of septic shock include:

• low blood pressure that makes you feel dizzy when you stand up
• a change in your mental state, such as confusion or disorientation
• diarrhoea
• nausea and vomiting
• cold, clammy and pale skin

These symptoms usually follow on from sepsis, which begins with weakness, chills, a rapid heart rate and rapid breathing rate. Read more about the preceding signs of sepsis.

Septic shock is a medical emergency. If you think that you or someone in your care has this, phone 999 and ask for an ambulance.

Treating septic shock

If you have septic shock, you will usually be admitted to an intensive care unit (ICU) as an emergency so your body’s functions and organs can be supported while the infection is treated.

Treatment may include:

• oxygen therapy
• fluids given directly through a vein (intravenous)
• medication to increase your blood flow
• antibiotics 
• surgery, in some cases

Read more about treating septic shock.

Complications of septic shock

A person’s chance of surviving septic shock will depend on the cause of infection, the number of organs that have failed and how soon treatment is started.

Complications of septic shock can include:

• lungs not being able to take in enough oxygen (respiratory failure)
• the heart not being able to pump enough blood around the body (heart failure)
• kidney injury or failure
• abnormal blood clotting

These are serious health conditions that will need to be treated urgently. Septic shock can be fatal because of complications such as these.

The Map of Medicine is used by doctors throughout the NHS to determine the best treatment options for their patients. NHS Choices offers everyone in England exclusive and free access to this cutting-edge internet resource, which lets you see exactly what your doctor sees.

The information in the Map has been approved by the UK’s leading clinical experts, is based on the best available clinical evidence, and is continually updated. To take advantage of this unique resource go to:

Map of Medicine: neutropenic sepsis in cancer patients

Sepsis and septic shock are medical emergencies and must be treated immediately.

If you have sepsis, it’s likely you will be admitted to an intensive care unit (ICU) for urgent treatment and to carefully monitor your progress. In some cases, treatment may begin in the emergency department.

You may be connected to various tubes and machines to measure:

• your blood pressure
• how much urine you produce
• how much oxygen is in your blood

Oxygen therapy

To help you breathe more easily, you will be given oxygen through one of the following:

• a face mask
• a tube inserted into your nose
• an endotracheal tube inserted into your mouth

If you have severe shortness of breath, a mechanical ventilator may be used.

Increasing blood flow

If you have septic shock, you will probably be given fluids directly into a vein. This will help raise your blood pressure by increasing the amount of fluid in your blood.

To increase the blood flow to your vital organs, such as your brain, liver, kidneys and heart, you may be prescribed:

• inotropic medicines
• vasopressors

Inotropic medicines 

Inotropic medicines (inotropes), such as dobutamine, stimulate your heart. They increase the strength of your heartbeat, which helps get oxygen-rich blood to your tissues and organs where it is needed.

Vasopressors

Vasopressors include:

• dopamine
• adrenaline
• noradrenaline

These medicines will cause your blood vessels to narrow, increasing your blood pressure and the flow of blood around your body. This will allow your vital organs to start functioning properly.

Antibiotics

Antibiotics are often used to treat sepsis and septic shock as these are usually caused by a bacterial infection.

The type of antibiotic that will be effective in treating the infection will depend on the type of bacterial infection and where in the body the infection started.

To increase your chances of survival, you may be started on antibiotics before the results of these tests are known. Initially, two or three types of antibiotics may be used. Once the results are known and the bacteria responsible for the infection have been identified, the most effective type of antibiotic can be used.

Surgery

In severe cases of sepsis or septic shock, the large decrease in blood pressure and blood flow can cause organ tissue to die. If this happens, surgery may be required to remove the dead tissue.

You may also need surgery to remove the cause of your infection, for example:

• draining a collection of pus (an abscess)
• removing infected tissue
• removing a medical device, such as a heart valve