September - Sepsis awareness month
Most infections don't become sepsis. But when sepsis does develop, recognizing that something has changed—and acting quickly—can be lifesaving.
It might begin with something that seems familiar: a urinary tract infection, pneumonia, an infected wound or another infection. Then the person suddenly seems much sicker than expected. They may become confused, short of breath, extremely uncomfortable, feverish or unusually cold.
This is what makes sepsis so important to understand. According to the CDC, sepsis is the body's extreme response to an infection, and without rapid treatment it can lead to tissue damage, organ failure and death. It is a life-threatening medical emergency, not something to monitor at home while waiting to see whether it improves.
What Actually Happens During Sepsis?
When you develop an infection, your immune system normally responds to fight the bacteria, virus, fungus or other organism responsible. In sepsis, the body's response to an infection becomes extreme and triggers a chain reaction that can begin damaging its own tissues and organs.
The original infection doesn't necessarily have to seem dramatic. CDC says infections leading to sepsis commonly begin in the lungs, urinary tract, skin or gastrointestinal tract. Bacterial infections cause many cases, although viral and fungal infections can also lead to sepsis.
That means sepsis isn't itself something you “catch” from another person in the way you might catch influenza. Instead, it develops as a dangerous response to an infection already occurring in the body.
The Warning Signs You Shouldn't Ignore
One of the challenges with sepsis is that its early symptoms can resemble other illnesses. Fever, weakness and feeling generally unwell can occur with many infections, so there isn't always one unmistakable symptom telling you that sepsis has begun.
The CDC advises watching for signs including confusion or disorientation, shortness of breath, extreme pain or discomfort, fever or shivering, feeling very cold, a high heart rate or weak pulse, and clammy or sweaty skin.
What can be particularly concerning is a person with an infection who appears to be getting significantly worse rather than better. Someone who suddenly seems confused, has trouble breathing or appears severely ill needs urgent medical evaluation.
CDC's current guidance is straightforward: if you or someone you care for has an infection that isn't getting better or is getting worse, get medical care immediately and ask whether the infection could be leading to sepsis. (CDC)
Can a Blood Test Tell You If You Have Sepsis?
This is where sepsis differs from conditions that can be identified primarily through a particular laboratory result.
There isn't one blood test that, by itself, diagnoses sepsis.
Doctors consider the whole clinical picture: the person's symptoms, vital signs, suspected infection, medical history and laboratory findings. CDC notes that healthcare professionals look for physical findings such as fever, increased heart rate, low blood pressure and breathing difficulties, while laboratory testing can look for infection and signs of organ damage.
Several blood tests can provide important clues, however. These tests can help doctors understand whether an infection may be present, how the body is responding and whether organs are beginning to be affected.
Importantly, suspected sepsis is not an appropriate situation for routine self-ordered outpatient testing. If symptoms suggest sepsis, seeking emergency medical care is far more important than ordering laboratory tests and waiting for results.
Why a CBC May Be Checked
A Complete Blood Count (CBC) is commonly used when clinicians are investigating infection and many other medical conditions.
Among other measurements, a CBC looks at white blood cells—the immune cells involved in responding to infections. An unusually high white blood cell count can occur with infection, although a low count can also be significant in someone who is seriously ill.
A CBC also provides information about hemoglobin and platelets. Platelets become particularly important because severe sepsis can affect the body's clotting system.
But a CBC cannot answer the question “Do I have sepsis?” on its own. An abnormal white blood cell count can occur for many reasons, and someone with sepsis doesn't necessarily have the same laboratory pattern as another patient. (Sepsis Alliance)
For general wellness purposes—not suspected sepsis—USLabTesting offers panels that include CBC measurements.
→ Explore General Health & Wellness Testing
Blood Cultures: Looking for the Infection Behind the Emergency
When doctors suspect sepsis, one of their priorities is determining what infection may be responsible.
Blood cultures can help identify bacteria or fungi in the bloodstream. CDC specifically lists blood cultures among the tests healthcare providers may use to identify the organism responsible for an infection leading to sepsis. (CDC)
Blood cultures are different from routine blood work. Samples may be collected from different sites, and the laboratory needs time to determine whether microorganisms grow from those samples.
Doctors don't necessarily wait for those final culture results before beginning treatment when sepsis is strongly suspected. Because sepsis can progress rapidly, treatment may need to begin while diagnostic testing is still underway.
Lactate Can Tell Doctors Something Different
Another measurement you may hear about in discussions of sepsis is lactate.
Lactate can rise when tissues aren't receiving or using oxygen normally, although elevated lactate isn't specific to sepsis and can occur in several other medical situations.
In someone who is critically ill with an infection, however, an elevated lactate level can provide doctors with important information about how severely the body may be affected. Sepsis Alliance lists lactate among the common blood tests used when evaluating suspected sepsis. (Sepsis Alliance)
Again, lactate isn't a stand-alone “sepsis test.” Doctors interpret it alongside the person's symptoms, vital signs and other laboratory findings.
What Is Procalcitonin?
Procalcitonin, sometimes abbreviated PCT, is another laboratory measurement associated with serious infection.
Normally, very little procalcitonin is present in the blood. Levels may rise considerably during serious bacterial infections. According to MedlinePlus, procalcitonin testing may help clinicians assess suspected bacterial infection or sepsis, evaluate severity, make treatment decisions and monitor response to treatment. (MedlinePlus)
This is primarily a test used in the context of someone who is already seriously ill or receiving hospital care. It shouldn't be interpreted as a general screening test for people who feel otherwise well.
Doctors Also Want to Know How the Organs Are Coping
Sepsis isn't only about identifying an infection. Doctors also need to know whether that infection and the body's response to it are affecting vital organs.
That's why laboratory evaluation can include measurements related to kidney function, liver function, electrolytes, blood clotting and other aspects of organ function.
For example, creatinine can provide information about kidney function. Platelets and clotting tests can help assess changes in the blood's ability to clot, while other laboratory measurements may provide information about liver function and metabolic disturbances.
This broader approach makes sense because sepsis can affect multiple systems at once. The goal isn't simply to find an abnormal number; it's to understand what is happening throughout the body and respond quickly.
For general education about kidney health, you can also read Signs of Kidney Disease: Recognizing the Early Warning Signs and Understanding Creatinine: What It Is and Its Importance.
Why Sepsis Can Be Difficult to Recognize
Imagine having the flu and feeling feverish, exhausted and achy. Those symptoms alone wouldn't necessarily make you think about sepsis.
Now imagine you already know you have a urinary tract infection, pneumonia or infected wound, and instead of gradually improving you suddenly feel dramatically worse. You're confused, struggling to breathe, experiencing severe discomfort or becoming clammy and weak.
That change matters.
Sepsis symptoms overlap with other illnesses, which is one reason recognizing the combination of an infection and a rapidly worsening condition is so important.
You also don't need to wait until every classic symptom appears. CDC says a person with sepsis may have one or more of its listed signs and symptoms.
Who Is More Likely to Develop Sepsis?
Anyone who develops an infection could potentially develop sepsis, but the risk isn't equal for everyone.
CDC identifies several groups at increased risk, including adults 65 and older, children younger than one year, people with weakened immune systems, people with chronic medical conditions, and people who have recently experienced severe illness, hospitalization or surgery. People who have previously survived sepsis are also at greater risk.
Still, being young or generally healthy doesn't make sepsis impossible. This is why awareness of the warning signs matters even if you don't consider yourself “high risk.”
How Common Is Sepsis?
Sepsis isn't a rare medical curiosity.
The CDC estimates that approximately 1.7 million adults and more than 18,000 children in the United States develop sepsis each year. At least 350,000 adults who develop sepsis die during hospitalization or are discharged to hospice.
CDC also reports that most sepsis cases begin before the patient reaches the hospital. That makes public awareness especially important: recognizing that an infection appears to be getting worse can influence how quickly someone seeks emergency care.
What Happens If Doctors Suspect Sepsis?
When healthcare professionals believe someone may have sepsis, things can move quickly—and that's intentional.
Doctors may collect blood and other samples, monitor blood pressure and oxygen levels, evaluate organ function and begin treatment for the suspected infection.
Antibiotics are an important treatment when bacterial infection is suspected, while intravenous fluids may be needed to support circulation. Some patients require additional treatments to maintain blood pressure or support organs. Surgery may sometimes be necessary to remove infected or damaged tissue.
The exact treatment depends on the infection, the person's condition and which organs are being affected.
What matters most is that suspected sepsis is evaluated and treated quickly.
Sepsis and Septic Shock Aren't Quite the Same Thing
You may hear the terms sepsis and septic shock used together, but they aren't interchangeable.
Sepsis describes the body's dangerous response to infection with resulting organ dysfunction. Septic shock is a particularly severe form in which circulatory and metabolic abnormalities create a much greater risk of death.
For patients and families, the practical message is simpler: you don't need to determine which stage someone has before seeking help.
If sepsis is a possibility, medical evaluation shouldn't wait.
Can Sepsis Be Prevented?
Not every case of sepsis can be prevented, but reducing infections and treating them appropriately can reduce opportunities for sepsis to develop.
CDC recommends staying up to date with appropriate vaccinations, managing chronic medical conditions, practicing good hygiene and handwashing, and keeping cuts clean and covered while they heal.
It's equally important to pay attention when an infection isn't behaving as expected. If an infection seems to be worsening rather than improving, particularly when new symptoms such as confusion, difficulty breathing or severe discomfort develop, seek medical care.
What If You Recently Had an Infection and Still Don't Feel Right?
Recovery doesn't always happen immediately after an infection. Feeling tired for a period afterward doesn't automatically mean you have sepsis.
What matters is the overall pattern.
Gradual improvement is different from suddenly becoming severely ill. An infection accompanied by new confusion, shortness of breath, extreme pain, clammy skin, a weak pulse or a significant deterioration in your condition deserves urgent medical attention.
When you're uncertain and concerned that an infection is becoming significantly worse, seeking professional medical evaluation is safer than trying to diagnose the situation yourself.
The Most Important Thing to Remember About Sepsis
There are many laboratory measurements associated with sepsis: CBC, blood cultures, lactate, procalcitonin, kidney and liver markers, platelets and clotting tests among them.
But none of those should distract from the most important message.
Sepsis is an emergency, not a condition to confirm through at-home or routine outpatient blood testing.
If you or someone you're caring for has an infection and becomes significantly worse—especially with confusion, difficulty breathing, extreme pain or discomfort, fever or feeling very cold, a high heart rate or weak pulse, or clammy skin—seek immediate medical care. CDC specifically encourages people concerned about a worsening infection to ask healthcare professionals, “Could this infection be leading to sepsis?”
Blood tests can help doctors understand what is happening.
Recognizing the warning signs is what helps get someone to those doctors in time.
Important Medical Information
This article is provided for general educational purposes and isn't intended to diagnose sepsis or replace emergency medical care. Sepsis is a life-threatening medical emergency requiring immediate professional evaluation and treatment.
If you think you or someone else may have sepsis, do not order routine laboratory testing and wait for the results. Seek emergency medical attention immediately. In the United States, call 911 for a medical emergency.