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Written by Ada’s Medical Knowledge Team

Updated on

What is sepsis?

Sepsis is a whole-body response to an infection in the blood. This severe condition is also known as blood poisoning, or septicemia. Sepsis occurs when an infection spreads from one location, for example, the lungs, the bladder or the skin, into the blood. Usually, when an infection is present in the body, it is limited to the system or area it affects, for example, a urinary tract infection usually does not spread beyond the urinary tract.

Sepsis occurs when an infection spreads throughout the body, prompting a full-body, or systemic, response. 1 The risk of sepsis increases if the infection is left untreated or is not adequately treated. 2

Sepsis can be caused by bacterial, viral, or fungal infections. Most cases of sepsis are the result of bacterial infection. As a result, sepsis can be defined as a full-body response to bacteremia, which is the presence ofbacteria in the blood. 1

Elderly people and people with other medical conditions are at higher risk of getting sepsis than the general population. The main symptoms include fever, chills, confusion, rapid pulse and drowsiness. Sepsis needs to be treated urgently in a hospital and is treated with antibiotics and fluids.

Septicemia, SIRS, and septic shock

The term septicemia is often used as a synonym for sepsis, but medically speaking, they are separate, though related, conditions. Technically, septicemia is an infection of the blood, while sepsis affects the body as a whole. 3

Sepsis has also been known as SIRS, or Systemic Inflammatory Response Syndrome, but this term is now considered to be out of date. 4

Septic shock is a type of sepsis associated with abnormalities of the circulatory system, cell function and metabolic processes. Septic shock is associated with higher mortality rates than sepsis. In septic shock, multiple organ failure can occur. The lungs, kidneys and liver may be affected. It is often caused by bacterial infections acquired in hospital. 5

Sepsis symptoms

Symptoms of sepsis include:

  • Fever or feeling cold
  • Chills
  • A strong feeling of illness
  • Drowsiness
  • Fast pulse
  • Fast breathing
  • Confusion

As the sepsis gets worse, people may have very cold and blue hands and feet, urinate less and lose consciousness altogether. There may also be signs of the underlying infection. These signs can vary greatly, depending on factors, including where the infection has begun and what kind of infectious agents it is caused by, and can include: 4

Good to know: In some people, especially children, infants and the elderly, the symptoms of sepsis may be vague and non-specific. It is important to seek medical help immediately if sepsis is suspected. If an affected person is known to have recently had an infection or to have an infection currently, sepsis should be considered a possibility, and medical help should be found as soon as possible.

The common symptoms of sepsis are: 4 5 6

  • Fever, defined as a body temperature of above 38 C / 100.4 F, with or without chills
  • Low body temperature, usually defined as below 36 C / 96.8 F
  • Cold extremities, which may also be bluish or mottled
  • Sweating
  • Rapid breathing
  • Rapid heartbeat
  • Mental confusion, grogginess, lack of alertness, or unresponsiveness
  • Cold and warm shock

In warm shock, the skin becomes warms and the heart rate increases. This is due to increased cardiac output making the arteries dilate, increasing blood pressure.

In cold shock, which follows, the cardiac output decreases. Correspondingly, the blood pressure drops, and the skin becomes chill, mottled, pale, bluish and/or clammy.

Symptoms of sepsis in babies and children

The symptoms of sepsis can be different in children. It is important to remember that young children may not be able to tell caregivers whether they feel ill or how ill they feel. Children, toddlers and infants with sepsis may: 3

  • Feel unusually cold to the touch
  • Have blotchy, blue, pallid and/or clammy skin
  • Have a rash that does not fade when pressed
  • Breathe rapidly
  • Be unwilling to eat or take feeds
  • Vomit or complain of nausea
  • Produce very little or no urine
  • Be difficult to wake up or rouse

If you are at all concerned that your infant or a child in your care may have sepsis, it is best to take them to a doctor as soon as possible. If you are concerned that your child or a child in your care might have an infection, you can do a free symptom assessment at any time using the Ada app.

Neonatal sepsis

Newborn babies are vulnerable to neonatal sepsis, a condition which results from an infection occurring during the early days of life. 7 Neonatal sepsis usually results from a bacterial infection. There are two main types of neonatal sepsis: 8

  1. Early onset neonatal sepsis, which occurs within the first three days of life and is usually the result of an infection picked up from the infant’s mother during or before birth. Symptoms of early onset neonatal sepsis can appear within six hours of birth.
  2. Late onset neonatal sepsis, which occurs between the ages of four days and three months, is usually the result of an infection picked up from the environment, such as the clinic or hospital. 8

Good to know: While most cases of neonatal sepsis are caused by bacterial infections, it is also possible for viral infections to lead to the disorder. The herpes simplex virus, enterovirus and adenovirus have all been found to cause neonatal sepsis.

Factors that increase a baby’s risk of developing early-onset neonatal sepsis include: 7

  • A Group B streptococcal infection in the mother
  • Preterm delivery
  • The mother’s waters breaking more than 18 hours before the baby is born
  • Chorioamnionitis, an infection of the placenta and amniotic fluid

Factors that increase a baby’s risk of late onset neonatal sepsis include: 8

  • A long stay in hospital after birth
  • A catheter or in-dwelling IV line
  • Use of antibiotics

Signs and symptoms of neonatal sepsis

The signs of neonatal sepsis are not always very obvious, and caregivers of at-risk babies should be vigilant. Symptoms of neonatal sepsis include: 7 8

  • Lethargy, or less activity than usual
  • Reluctance to suckle, or loss of interest in suckling
  • Loss of appetite
  • Apnea, a temporary pause in breathing
  • Slow heartbeat
  • Fever or low body temperature
  • Changes in bowel movements, for example diarrhea or constipation
  • Seizures
  • Vomiting
  • Jaundice

Good to know: As with other forms of sepsis, early detection and prompt treatment greatly improve the chances of a good outcome in babies with neonatal sepsis. If you are concerned that your baby may have an infection, consult your health provider as soon as possible.

Risk Factors and Causes&Causes

Elderly people are at higher risk of developing sepsis, though it can affect people of every age. People with some medical conditions, such as cancer, a weakened immune system or diabetes, are at increased risk of this condition. Sepsis occurs when an infection spreads from a particular location into the blood; for example, from the lungs, the bladder or the skin. This causes a whole-body response, as the immune system tries to fight the infection.

Some groups of people are at higher risk of developing sepsis than others. These groups include: 3 4

  • People older than 75 years of age or children younger than one year of age
  • People who have diabetes mellitus
  • People who have recently had surgery or invasive medical procedures
  • People who have recently sustained severe burns
  • People who have in-dwelling IV lines or catheters
  • People who take high doses of steroids
  • Users of intravenous recreational drugs
  • People who use excessive alcohol
  • People who have cirrhosis of the liver
  • People with weakened immune systems, for example as a result of HIV infection or chemotherapy
  • Pregnant women

This list is not exhaustive, and it is possible for any person to develop sepsis. If you are concerned that your or a loved one may have sepsis, you can do a free symptom assessment using the Ada app at any time.

Underlying conditions

Sepsis arises following an infection or injury to the body. The gastrointestinal tract, the genitourinary tract, soft tissue, the skin, the pelvic area and the the respiratory system are all common sites of infections that can progress to sepsis. 4 6

There are many conditions affecting the renal and genitourinary systems, which can lead to sepsis. These include: 6

Good to know: Sepsis affecting the urinary system is often known as urosepsis.

Conditions affecting the gastrointestinal system, which can lead to sepsis include: 6

Conditions affecting the respiratory system, which can lead to sepsis include: 6

  • Pneumonia
  • Pleural empyema, a condition in which a bacterial infection causes pus to collect in between the pleural membranes that surround the lungs
  • Lung abscess
  • Influenza

Conditions affecting other systems and structures in the body, which can lead to sepsis include: 6

Good to know: Just having one of the above conditions does not mean that the affected individual will develop sepsis. Most people who get bacterial infections do not develop sepsis. However, some people are more vulnerable to developing sepsis than others.

In addition, some medical procedures and devices can increase the risk of developing sepsis: 3 6 9

  • Open surgery
  • Prosthetic heart valves
  • Long-term catheters
  • Long-term intravenous lines
  • Breathing tubes and intubation
  • Recent use of antibiotics
  • Recent use of high-dose steroids
  • Chemotherapy

Bacteria involved in sepsis

Not all bacteria can cause sepsis. The species of bacteria most commonly responsible for sepsis include: 6 10 11 12

  • Methicillin-resistant staphylococcus aureus (MRSA)
  • Group B streptococcus
  • Staphylococcus pyogenes
  • Klebsiella
  • Escherichia coli
  • Pseudomonas aeruginosa

Good to know: Toxic shock syndrome, which is caused by Group A Streptococcus and Staphylococcus aureus, is not the same as sepsis but can lead to sepsis. For more information on toxic shock syndrome, see the FAQs.

When someone with suspected sepsis is examined by a doctor, the exact strain of bacteria responsible for their sepsis may not be known. The first line of treatment, therefore, is to administer a broad-spectrum antibiotic. For more information, see the section on treatment.

Diagnosis of sepsis

Diagnosis is often made from the appearance and physical examination of the affected person. Blood tests are taken to prove that an infection is the cause of the symptoms, to check the function of organs that might be affected by sepsis and to identify the cause of sepsis. Sepsis screening is an important part of the diagnostic process.

Sepsis screening

The SOFA score is used to determine how severely ill a person affected by sepsis is and assesses the risk of mortality. The SOFA score is determined by measuring organ function in the respiratory, cardiovascular, liver, kidney and neurological systems, as well as blood coagulation. As parts of the SOFA system require sending blood samples to a laboratory for testing, it is not very fast, and so the qSOFA is now used to make initial diagnoses instead.

The qSOFA, or quick Sepsis-Related Organ Failure Assessment, is used to determine the presence and severity of sepsis. It is a quicker, simpler version of the SOFA criteria. The qSOFA can be carried out at the affected person’s bedside and uses three criteria: 13

  • Altered mental state
  • Low blood pressure, defined as a systolic blood pressure of less than 100 mm/Hg
  • High respiratory rate, of 22 or more breaths a minute

The physician carrying out the qSOFA assessment assigns points according to the results of examinations of the affected person’s respiration, blood pressure, and mental state. If all three criteria are met, sepsis is present. 5

Both SOFA and qSOFA tests have to be carried out by trained medical professionals in a medical setting.

Blood and laboratory tests

Blood tests and bacterial cultures are an important part of diagnosing sepsis. Blood tests that are usually carried out include: 6

  • A complete blood count to identify clotting abnormalities and count the white blood cell levels
  • Laboratory cultures of the blood, to determine which bacterial species isbacteria are responsible for the sepsis and thereby guide antibiotic therapy.

Sometimes cultures are also carried out using samples of pus, nasal mucus, urine or phlegm, depending on the type of suspected underlying infection.

Read more about Blood Test Results »

Imaging tests

In cases where an abscess or localised infection is suspected to be the cause of sepsis, imaging studies may be carried out to aid diagnosis and treatment. Imaging tests commonly carried out during the diagnosis of sepsis include: 6

  • Chest X-rays to identify pneumonia or lung disorders
  • Abdominal ultrasound
  • Computed tomography (CT) scan
  • Magnetic resonance imaging (MRI)


Sepsis is a life-threatening condition which must be treated in a hospital. The key to successfully treating sepsis is to diagnose it as early as possible and thereafter to begin aggressive antibiotic and supportive treatment as soon as possible.

Sepsis is treated by giving antibiotics against the cause of the infection and fluids to increase blood pressure. The cause of the original infection should be identified and treated, or removed.

Hospital care for sepsis

Most people with sepsis will require hospitalization, and people who are severely affected may need to be treated in an Intensive Care Unit (ICU). Upon being admitted to hospital, the affected person will be given oxygen, breathing support, and vasopressors and fluids to support blood pressure and organ function. 4

In some cases, intravenous insulin may also be given to support blood glucose levels. While hospitalized, the affected person will be tested for inflammation markers, often several times a day, to monitor their condition. The duration of the stay in hospital will depend on the severity of the sepsis, the effectiveness of the treatment and the management of the underlying condition.

Antibiotic treatment

Because most cases of sepsis are the result of a severe bacterial infection, antibiotic treatment is one of the first lines of treatment against the disorder. Initial treatment with antibiotics is begun even before the pathogen responsible is identified, using a broad-spectrum antibiotic. Thereafter, the treatment will be adjusted according to what laboratory cultures identify as the cause of the infection. 6

Surgical procedures

If the sepsis has been identified as the result of an abscess, burns or an infected surgical incision or wound, surgical procedures may be needed to remove the source. In the case of an abscess, the abscess will need to be surgically drained. In other cases, such as burns or infected wounds, the affected tissue may need to be removed, along with any foreign objects.

Complications and long-term prognosis

Sepsis is a serious condition that needs to be treated promptly and aggressively to ensure a good outcome. There are several complications associated with sepsis, as well as a number of long-term effects which may impact the quality of life of people who have had the condition.

Waterhouse-Friderichsen syndrome

Waterhouse-Friderichsen syndrome is a rare complication, a condition in which the adrenal glands fail due to bleeding. The syndrome causes bleeding inside the adrenal glands and, because of the damage to the adrenal glands this causes, to adrenal insufficiency.

Symptoms include: 14 15

  • A rash, beginning as small pink patches or swellings that resemble pimples, which later expand into larger purple patches
  • Malaise and weakness
  • Dizziness
  • Cough
  • Joint and muscle pain
  • Fever
  • Rigors/chills
  • Nausea and vomiting
  • Headache
  • Low blood pressure
  • Fast heart rate

Good to know: Most cases are caused by severe infection with meningococcal bacteria, Group B streptococcus, Streptococcus aeruginosa, Staphylococcus pneumoniae or Staphylococcus aureus.

Waterhouse-Friderichsen Syndrome is a medical emergency, and anyone who shows symptoms of the syndrome should receive medical care immediately.

Disseminated intravascular coagulation

Sepsis can disturb the processes that control the blood’s clotting. As a result, disseminated intravascular coagulation can occu, and may be serious. In this condition, blood clots form throughout the body, and, as the chemicals that help blood to clot become depleted, bleeding occurs. This condition can lead to organ dysfunction and organ failure. 16

Long-term changes to quality of life: post-sepsis syndrome

Sepsis, because of its severity and the effects it has throughout the body, can cause after-effects of various kinds. These include: 17 18

  • Post-traumatic stress disorder
  • Amputations
  • Rehospitalization due to infection
  • Relapse of sepsis
  • Cognitive problems such as confusion
  • Cardiovascular problems
  • Muscle and joint pain
  • Insomnia and nightmares, or other sleep disorders
  • Anxiety and depression

Together, these make up post-sepsis syndrome, a condition which affects almost 50% of all sepsis survivors, particularly if they are older adults. People who were admitted to an ICU with sepsis may be more likely to have post-sepsis syndrome.


It is important that infections, such as pneumonia, bladder infections or skin infections, are assessed early by a doctor and treated with antibiotics. People who are at increased risk of vaccine-preventable infections, such as the elderly and people with other medical conditions, should make sure they keep their vaccinations up to date.

Sepsis FAQ

Q: Is sepsis fatal?
A: Sepsis can be fatal. It is one of the most common causes of death among hospitalized people. 19 However, improvements in care have reduced mortality rates in recent decades, and early detection and prompt appropriate treatment further improves the outcome.

Q: Is sepsis contagious?
A: No, sepsis is not contagious - it cannot spread from person to person. However, the underlying infection that has caused the sepsis may be contagious. 20

Q: Can sepsis cause red streaks on the skin?
A: Red streaks on the skin spreading from the site of an infected wound are a sign that the infection has spread to the lymph vessels. Red streaks are not a sign of sepsis itself, but can indicate that a skin infection such as erysipelas or cellulitis has begun in the affected area. 21 If left untreated, both erysipelas, which affects the upper layers of the skin, and cellulitis, which affect deeper layers of tissue, can potentially lead to sepsis. 22

Q: Can sepsis cause a skin rash?
A: Yes, it can. Some people with sepsis develop a hemorrhagic rash, which in its early stages looks like a cluster of small red dots, but can develop into larger spots that resemble bruises. 23

Q: What is toxic shock syndrome and how does it differ from sepsis?
A: Toxic shock syndrome (TSS) is a disorder caused by toxins produced by Staphylococcus aureus and/or Group A Staphylococcus. Toxic shock syndrome can lead to sepsis. It often results from infections affecting the skin, surgical wounds, abscesses, and sinus and bone infection. 24

Toxic shock syndrome has a sudden onset and can quickly become medically serious. TSS is potentially life-threatening and should be considered a medical emergency.The symptoms of TSS include: 25

  • Fever of 38.8 C / 102 F or higher
  • Pain
  • Rapid, sudden drop in blood pressure
  • Confusion
  • Fainting
  • Headache
  • Diarrhea and vomiting
  • Low or no urine output
  • Fatigue and weakness
  • Difficulty breathing
  • Rash

Q: What is Systemic Inflammatory Response Syndrome?
A: SIRS is a concept used to determine whether an affected person has sepsis, not a separate condition. An affected person is considered to have sepsis if they meet two or more of the SIRS criteria, which are: 26

  • Fever of 38 C / 100.4 F or more
  • Hypothermia of 36 C / 96.8 F or less
  • A pulse of more than 90 beats a minute
  • Rapid breathing, of more than 20 breaths a minute
  • An increase or decrease in the number of white blood cells in the blood, determined using a blood tests

In recent years, the medical communities have moved away from using it because it is no longer considered to be sufficiently sensitive or accurate. Most medical practitioners now use the qSOFA Score system to determine whether sepsis is present.

Q: Can influenza cause sepsis?
A: Although most cases of sepsis are the result of bacterial infection, it is possible for a viral infection to lead to sepsis. Influenza is a viral infection. However, it is rare for influenza itself to cause sepsis.