The Differences Between Sepsis and Septicemia

The terms are similar, but they're not interchangeable

A test tube rack of biohazardous samples in the lab. Credit: Greg Dale / Getty Images

Sepsis and septicemia are medical terms that refer to infections and your body's response to those infections. Both words originally stem from a Greek word, sepsin, which literally means "poison in putrid blood."

Sepsis and septicemia sometimes are used interchangeably, but they're not truly interchangeable — although the terms are closely related, their definitions are different. Read on to learn the correct use of each word when you're talking about infections.

Sepsis Is the Widespread Inflammation in Your Body

When your body is threatened with a severe infection — for example, pneumonia caused by bacteria — your immune system responds by releasing chemical messengers. These chemical messengers, which are used by your immune system to sound the alarm about the infection, cause inflammation throughout your body.

Sepsis is defined as this inflammatory response throughout your body. Without proper treatment, the inflammation resulting from the severe infection can damage your organs and potentially kill you. Your blood pressure will drop and your bodily systems can start to shut down.

Therefore, sepsis is a medical emergency. In fact, sepsis kills some 258,000 Americans each year, and survivors can have life-long effects from the disease. There are more than 1 million cases of sepsis in the U.S. annually.

Symptoms of Sepsis

If you're experiencing symptoms of sepsis, which include fever, chills, mental confusion, rapid heartbeat, shaking, and warm skin, you should seek immediate medical help.

In some people, the first signs of sepsis are confusion and rapid breathing.

Elderly people, babies and very young children, people with weakened immune systems, and people with a long-term chronic illness are most at risk from sepsis. Treatment can involve antibiotics, plus life support measures such as dialysis and a ventilator until the patient is stabilized.

There are many different infections that can cause sepsis. Some possible causes include meningitis, a urinary tract infection, a skin infection called cellulitis, and peritonitis, an infection in your bowel.

Infections also can start in the hospital from intravenous lines, surgical sites and from bedsores. In fact, sepsis is common in people admitted to the hospital for other reasons.

Some of these infections result from so-called "superbugs," which are types of bacteria that are resistant to many different antibiotics. These infections and the resulting sepsis are very difficult to treat.

Septicemia Is the Infection Itself

Sepsis is your body's inflammatory reaction to a severe infection. Septicemia, meanwhile, is the infection itself — it's defined as the bacteria in the blood that causes sepsis. Some people call septicemia "blood poisoning," and this term is pretty accurate since the overwhelming bacterial infection can indeed poison your blood.

Doctors and other medical personnel no longer use the term septicemia much — instead, to eliminate the inevitable confusion surrounding such like-sounding terms as sepsis and septicemia, clinicians often use "sepsis" to refer to the inflammatory response, and "bacteremia" to refer to the bacteria present in the bloodstream.

(Other types of infections, such as fungal infections, have different names.)

However, some doctors and hospitals do still use the older term "septicemia," in some cases interchangeably with sepsis. If you're confused about what exactly your doctor means, you should ask her to explain.


American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference Committee. Definitions for Sepsis and Organ Failure and Guidelines for the Use of Innovative Therapies in Sepsis. Chest. 1992. 101:1644-55.

Centers for Disease Control and Prevention. Sepsis Questions and Answers fact sheet.

Odeh M. Sepsis, septicaemia, sepsis syndrome, and septic shock: the correct definition and use. Postgraduate Medical Journal. 1996 Feb; 72(844): 66.

U.S. National Library of Medicine. Sepsis fact sheet. 

U.S. National Library of Medicine. Septicemia fact sheet