Sepsis can be triggered by an infection in any part of the body. The most common sites of infection leading to sepsis are the lungs, urinary tract, abdomen (tummy) and pelvis.

Sepsis may develop when you are already in hospital, for example if you have recently had surgery, have a urinary catheter fitted or have to stay in hospital for a long time – all increasing your risk of developing sepsis.

Sources of infection

Types of infection associated with sepsis include:

• lung infection (pneumonia)
• appendicitis
• an infection of the thin layer of tissue that lines the inside of the abdomen (peritonitis)
• an infection of the bladder, urethra or kidneys (urinary tract infection)
• an infection of the gallbladder (cholecystitis) or bile ducts (cholangitis)
• skin infections, such as cellulitis (this can be caused by an intravenous catheter that has been inserted through the skin to give fluids or medication)
• post-surgical (after surgery) infections
• infections of the brain and nervous system, such as meningitis or encephalitis
• flu (in some cases)

Sometimes, the specific infection and source of sepsis cannot be identified.

What causes the symptoms of sepsis?

Usually, your immune system will keep the infection limited to one place (known as a localised infection). Your body will produce white blood cells, which travel to the site of the infection to destroy the germs causing infection. A series of biological processes occur, such as tissue swelling, which helps fight the infection and prevents it spreading. This process is known as inflammation.

If your immune system is weak or an infection is particularly severe, it can quickly spread through the blood into other parts of the body. This causes the immune system to go into overdrive, and the process of inflammation affects the entire body.

This can cause more problems than the initial infection, as widespread inflammation damages tissue and interferes with the flow of blood. The interruption in blood flow leads to a dangerous drop in blood pressure, which stops oxygen reaching your organs and tissues.

People at risk

Everybody is potentially at risk of developing sepsis from minor infections, such as flu. However, some people are more vulnerable, including people who:

• have a medical condition that weakens their immune system, such as HIV or leukaemia
• are receiving medical treatment, such as chemotherapy or long-term steroids, that weakens their immune system
• are very young or very old
• are pregnant
• have a long-term health condition, such as diabetes
• have just had surgery, or have wounds or injuries as a result of an accident
• are on mechanical ventilation (where a machine is used to help you breathe)
• have drips or catheters attached to their skin
• are genetically prone to infections

Sepsis is a particular risk for people already in hospital due to another serious illness. Despite the best efforts of doctors and nurses to avoid infections being acquired in hospital, people who fall into the categories described above are still at an increased risk of developing sepsis.

Hospital-acquired bacterial infections, such as MRSA, tend to be more serious as these bacteria have often developed a resistance to many commonly used antibiotics.

Sepsis is often diagnosed based on simple measurements such as your temperature, heart rate, breathing rate and a simple blood test.

Other tests may help determine the type of infection, where it is located and which body functions have been affected. These can include:

• blood and urine cultures (where a sample of blood or urine is tested for infections)
• stool sample tests, if you have diarrhoea
• blood pressure tests
• a wound culture (where a small sample of tissue, skin or fluid is taken from the affected area for testing)
• respiratory secretion testing (where a sample of your saliva, phlegm or mucus is taken for testing)
• imaging studies such as an X-ray, ultrasound scan or computerised tomography (CT) scan
• kidney, liver and heart function tests
• a lumbar puncture (where a sample of fluid is extracted from your spine for testing)

In the case of suspected sepsis, it is important to get a diagnosis as soon as possible so that appropriate treatment can be given. This can help stop the progression of sepsis and reduce the risk of long-term damage to the body, or death.

Read more about treating sepsis.

Sepsis is a common and potentially life-threatening condition triggered by an infection.

In sepsis, the body’s immune system goes into overdrive, setting off a series of reactions including widespread inflammation, swelling and blood clotting. This can lead to a significant decrease in blood pressure, which can mean the blood supply to vital organs such as the brain, heart and kidneys is reduced.

If not treated quickly, sepsis can eventually lead to multiple organ failure and death.

Each year in the UK, it is estimated that more than 100,000 people are admitted to hospital with sepsis and around 37,000 people will die as a result of the condition.

Signs and symptoms of sepsis

Early symptoms of sepsis usually develop quickly and can include:

• a high temperature (fever)
• chills and shivering
• a fast heartbeat
• fast breathing

In some cases, symptoms of more severe sepsis or septic shock (when your blood pressure drops to a dangerously low level) develop soon after. These can include:

• feeling dizzy or faint
• confusion or disorientation
• nausea and vomiting
• diarrhoea
• cold, clammy and pale or mottled skin

Read more about the symptoms of sepsis.

When to seek medical advice

See your GP immediately if you have recently had an infection or injury and you have possible early signs of sepsis.

Severe sepsis and septic shock are medical emergencies. If you think that you or someone in your care has one of these conditions, call 999 and ask for an ambulance.

Read more about diagnosing sepsis.

Who’s at risk?

Anyone can develop sepsis after an injury or minor infection, although some people are more vulnerable. People most at risk of sepsis include those:

• with a medical condition or receiving medical treatment that weakens their immune system
• who are already in hospital with a serious illness
• who are very young or very old
• who have just had surgery or who have wounds or injuries as a result of an accident

Read more about the causes of sepsis.

How sepsis is treated

If sepsis is detected early and has not yet affected vital organs, it may be possible to treat the infection at home with antibiotics. Most people who have sepsis detected at this stage will make a full recovery.

Some people with severe sepsis and most people with septic shock require admission to an intensive care unit (ICU), where the body’s organs can be supported while the infection is treated.

As a result of problems with vital organs, people with severe sepsis are likely to be very ill and up to four in every 10 people with the condition will die. Septic shock is even more serious, with an estimated six in every 10 cases proving fatal.

However, if identified and treated quickly, sepsis is treatable and in most cases leads to full recovery with no lasting problems.

Read more about treating sepsis.

The symptoms of sepsis may develop after a localised infection (infection limited to one part of the body) or an injury.

The most common sites of infection leading to sepsis are the lungs, urinary tract, abdomen (tummy), and pelvis.

In some cases, sepsis may develop when you are already in hospital, for example if you have recently had surgery and a drip or catheter has been connected to your body. Read more about the causes of sepsis.

The symptoms of sepsis usually develop quickly and can include:

• a high temperature (fever)
• chills and shivering
• a fast heartbeat
• fast breathing

In some cases, symptoms of more severe sepsis or septic shock (when your blood pressure drops to a dangerously low level) can develop within hours. These can include:

• feeling dizzy or faint
• a change in mental state, such as confusion or disorientation
• diarrhoea 
• nausea and vomiting
• slurred speech
• severe muscle pain
• severe breathlessness
• decreased urine production (for example, not urinating for a day)
• cold, clammy and pale or mottled skin
• loss of consciousness

When to seek medical advice

See your GP immediately if you have recently had an infection or injury and you have possible early signs of sepsis.

Severe sepsis and septic shock are medical emergencies. If you think that you or someone in your care has one of these conditions, call 999 and ask for an ambulance.

Treatment of sepsis varies depending on the site and cause of the initial infection, the organs affected and the extent of any damage.

If your sepsis is detected early enough and has not yet affected vital organs, it may be possible to treat the condition at home with antibiotic tablets. Most people who have sepsis detected at this stage will make a full recovery.

If the sepsis is severe or you develop septic shock (when your blood pressure drops to a dangerously low level), you will need emergency hospital treatment and may require admission to an intensive care unit (ICU). ICUs are able to support any affected body functions, such as breathing or blood circulation, while the medical staff focus on treating the infection.

Antibiotics

The main treatment for sepsis, severe sepsis or septic shock is antibiotics.

If you have severe sepsis and septic shock, antibiotics will be given directly into a vein (intravenously). There will not usually be time to wait until a specific type of infection has been identified, so ‘broad-spectrum’ antibiotics will initially be given. Broad-spectrum antibiotics are designed to work against a wide range of known infectious bacteria and will usually cure most common infections.

Ideally, antibiotic treatment should start within an hour of diagnosis to reduce the risk of serious complications or death.

Once a specific bacterium has been identified, a more ‘focused’ antibiotic can be used. This has the advantage of reducing the chance of the bacteria becoming resistant to antibiotics.

How long you will need intravenous antibiotics depends on your individual circumstances, such as the severity of the sepsis. Typically, intravenous antibiotics are changed to tablets in two to four days but on occasions they may have to be given for up to seven to 10 days or longer.

If the sepsis is caused by a virus, antibiotics will not work. However, it is likely that antibiotics will be started anyway because it would be too dangerous to delay antibiotic treatment until tests are able to confirm the specific cause of the infection. You will then need to wait until your immune system starts to tackle the infection, although antiviral medication may be given in some cases.

Intravenous fluids

If you have sepsis, your body requires increased amounts of fluid to prevent dehydration and kidney failure. Therefore, you will usually be given fluids intravenously during the first 24 to 48 hours after admission if you have severe sepsis or septic shock.

It is important that the doctors know how much urine your kidneys are making when you have sepsis, so they can spot signs of kidney failure. Therefore, if you are admitted with severe sepsis or septic shock, usually you will have a catheter inserted into your bladder to monitor your urine output.

Oxygen

Your body’s oxygen demand will go up if you have sepsis, so you will usually be given oxygen through a mask or tubes in your nostrils when admitted to hospital with sepsis if the level of oxygen in your blood is low.

People with chronic lung conditions, such as chronic obstructive pulmonary disease (COPD), or with pneumonia are particularly vulnerable to this problem.

Treating the source of the infection

If a source of the infection can be identified, such as an abscess (collection of pus) or infected wound, this will also need to be treated.

For example, any pus may need to be drained away, or in more serious cases, surgery may be needed to remove the infected tissue and repair any damage.

Increasing blood pressure

Medications called vasopressors are used if you have low blood pressure caused by sepsis. The two types of vasopressors used in the treatment of sepsis are dobutamine and noradrenaline.

These medications can help to increase blood pressure by stimulating the muscles involved in pumping blood around the body and constricting (narrowing) the blood vessels.

Vasopressors are normally given intravenously while you are in an ICU. Extra fluids may also be given intravenously to help increase blood pressure.

Other treatments

Depending on your condition and the effect sepsis has had on your body, you may also require additional treatments such as:

• corticosteroids or insulin medication
• a blood transfusion
• mechanical ventilation (where a machine is used to help you breathe)
• dialysis (where a machine filters your blood to replicate the function of your kidneys)