Sepsis: Causes, Warning Signs, and Emergency Treatment

Every year, at least 1.7 million adults in the United States develop sepsis, and at least 350,000 adults who develop sepsis die during their hospitalization or are discharged to hospice, according to the CDC – making it one of the leading causes of death in U.S. hospitals. Globally, the World Health Organization has estimated on the order of 49 million sepsis cases and 11 million sepsis-related deaths a year. Despite these staggering numbers, sepsis remains poorly understood by the general public. It is not an infection itself but the body’s extreme and dysregulated response to an infection – a response so overwhelming that it can damage the body’s own organs and tissues. Every hour of delayed treatment is estimated to increase mortality. Recognizing the warning signs is not optional knowledge – it is potentially lifesaving. For an overview of serious health conditions, visit our medical conditions guide.

What Is Sepsis?

Sepsis is defined as life-threatening organ dysfunction caused by a dysregulated host response to infection. According to the Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3), published in JAMA in 2016 and still the prevailing framework, sepsis is fundamentally about organ dysfunction rather than simply the presence of infection with inflammation. The older terms “septicemia” (blood poisoning) and “SIRS” (systemic inflammatory response syndrome) have been largely replaced or deemphasized in clinical practice.

The body’s immune system normally fights infection through a coordinated inflammatory response. In sepsis, this response becomes uncontrolled – inflammation spreads throughout the body, damaging blood vessels, impairing blood flow, and leading to organ failure. Multiple organ systems can be affected simultaneously: the lungs (acute respiratory distress syndrome), kidneys (acute kidney injury), heart (septic cardiomyopathy), liver, brain (septic encephalopathy), and blood-clotting system (disseminated intravascular coagulation).

Septic shock is the most severe form of sepsis, characterized by profound circulatory failure: dangerously low blood pressure that does not respond adequately to intravenous fluid resuscitation, requiring vasopressor medications (drugs that constrict blood vessels to raise blood pressure), along with elevated blood lactate levels indicating that tissues are not getting enough oxygen. According to the CDC, septic shock carries a high mortality rate even with aggressive treatment.

What Causes Sepsis?

Any infection can trigger sepsis, though certain infections are more commonly responsible. Bacterial infections are the most frequent cause, but viral infections (including influenza and COVID-19), fungal infections, and parasitic infections can all lead to sepsis. The CDC identifies the most common sources of infection leading to sepsis as:

• Lungs: Pneumonia is among the most common infections leading to sepsis.
• Urinary tract: Kidney and bladder infections, particularly in older adults and those with urinary catheters.
• Abdomen: Appendicitis, peritonitis, diverticulitis, gallbladder infection (cholecystitis), and perforated bowel.
• Skin and soft tissue: Cellulitis, wound infections, and surgical site infections.
• Bloodstream: Infections from central venous catheters, intravenous drug use, or heart-valve infection (endocarditis).

Healthcare-associated infections are a significant source of sepsis. Central line-associated bloodstream infections, catheter-associated urinary tract infections, ventilator-associated pneumonia, and surgical site infections can all progress to sepsis. Antibiotic-resistant organisms – including MRSA, vancomycin-resistant enterococci, and carbapenem-resistant Enterobacteriaceae – can cause particularly difficult-to-treat sepsis, which is one reason antibiotic stewardship is a public-health priority.

Who Is at Risk?

While anyone with an infection can develop sepsis, certain populations are at substantially higher risk. High-risk groups include adults over 65 (who account for a large share of sepsis cases), infants under 1 year, people with chronic conditions (diabetes, chronic lung disease, kidney disease, liver disease, heart failure), people with weakened immune systems (HIV/AIDS, cancer treatment, organ-transplant recipients, those on immunosuppressive medications), and people with recent hospitalization or surgery.

Additional risk factors include antibiotic-resistant infections, indwelling medical devices (catheters, ports, ventilators), recent severe illness, pregnancy and the postpartum period, and substance use (including alcohol and injection drugs). Poverty, limited healthcare access, and delays in seeking treatment also contribute to worse sepsis outcomes. The disproportionate impact on vulnerable populations makes sepsis both a clinical and a public-health challenge.

Recognizing the Warning Signs in Adults

Early recognition is the single most important factor in surviving sepsis. The signs can be subtle initially and are easily mistaken for a worsening of the underlying infection, the flu, or other common illnesses. The Sepsis Alliance promotes the “It’s About TIME” acronym to help the public remember key warning signs:

• T – Temperature: Higher or lower than normal (fever, or an abnormally low temperature – a low temperature is particularly concerning).
• I – Infection: Signs and symptoms of an infection, which may or may not be obvious.
• M – Mental decline: Confusion, sleepiness, difficulty waking, or altered behavior.
• E – Extremely ill: “I feel like I might die” – severe pain or discomfort, shortness of breath, and a rapid heart rate.

Other important warning signs include rapid breathing, an elevated heart rate, mottled or discolored skin, clammy or sweaty skin, reduced urine output, and a dramatic worsening that seems out of proportion to what you would expect from the underlying infection. In older adults, confusion or delirium may be the earliest – and sometimes the only – sign.

When to seek emergency care: Call 911 or go to the nearest emergency room immediately if you or someone you are caring for has a known or suspected infection AND develops confusion or altered mental status, difficulty breathing, a rapid heart rate, extreme pain, fever with shaking chills that do not improve, or skin that appears mottled, blue, or abnormally pale. Tell the medical team, “I am worried about sepsis.” This prompts a rapid, protocol-driven evaluation that can save critical time.

Warning Signs in Babies and Children

Sepsis in children and infants can look different from sepsis in adults, and young children can go downhill quickly. Trust your instincts – a caregiver who feels that something is seriously wrong is often right. Seek emergency care immediately (call 911 or go to the ER) if a baby or child has any of the following:

• Is not eating or drinking, or is not feeding normally (in infants).
• Has not had a wet diaper in many hours, or is producing much less urine than usual.
• Is very sleepy, difficult to wake, or unusually floppy or unresponsive.
• Is breathing fast, grunting, or struggling to breathe.
• Has skin that looks mottled, blotchy, bluish, or very pale, or a rash that does not fade when you press a glass against it.
• Has a seizure or convulsion.
• Feels abnormally cold to the touch, or has a high fever that does not improve.

As with adults, say “I am worried about sepsis” so the care team moves quickly. If you are unsure whether symptoms warrant the ER versus urgent care, our guide on urgent care versus the emergency room can help – but any of the danger signs above means the emergency room or 911, not urgent care.

How Sepsis Is Diagnosed

There is no single test that definitively diagnoses sepsis. Instead, diagnosis is based on clinical assessment combined with laboratory and imaging findings. The Sepsis-3 criteria use the Sequential Organ Failure Assessment (SOFA) score – an increase of 2 or more points from baseline in the presence of infection defines sepsis. A bedside screening tool called qSOFA (quick SOFA) has been used to flag patients outside the ICU who may have sepsis based on three criteria: altered mental status, a fast respiratory rate, and low systolic blood pressure.

Laboratory tests include blood cultures (ideally obtained before antibiotics are started), complete blood count (white blood cells may be very high or very low), lactate level (elevated lactate indicates tissue hypoperfusion and is a marker of severity), a comprehensive metabolic panel (assessing kidney and liver function), coagulation studies, and inflammatory markers (procalcitonin, C-reactive protein). Imaging studies (chest X-ray, CT scan, ultrasound) help identify the source of infection.

Blood cultures are positive in only a minority of sepsis cases, so negative cultures do not rule out sepsis. The clinical picture – infection plus organ dysfunction – is what drives the diagnosis and treatment decision. Waiting for culture results before starting treatment can be fatal, which is why clinicians treat first based on the most likely source and refine later.

Emergency Treatment: The Golden Hours

Sepsis treatment is time-critical and always happens in a hospital. The Society of Critical Care Medicine’s Surviving Sepsis Campaign established evidence-based bundles – sets of interventions to be completed within specific timeframes to optimize outcomes, including the Hour-1 Bundle for the sickest patients.

Early management includes: blood cultures drawn (before antibiotics when possible), broad-spectrum intravenous antibiotics administered promptly, a lactate level measured, and, for patients with low blood pressure or a high lactate, rapid intravenous fluid resuscitation. Each hour of delay in administering appropriate antibiotics is associated with worse outcomes, which is why speed matters so much.

Broad-spectrum antibiotics – covering the most likely organisms based on the suspected infection source and local resistance patterns – are started empirically. Once culture results identify the specific organism and its susceptibilities, antibiotics are narrowed (de-escalated) to the most targeted effective agent. This reduces the risk of antibiotic resistance and side effects. Finding and controlling the source of infection – draining an abscess, removing an infected catheter, or operating when needed – is a crucial part of treatment.

If blood pressure does not respond adequately to intravenous fluids, vasopressors – norepinephrine is the usual first-line agent – are started to maintain adequate perfusion pressure. Patients with septic shock typically require ICU admission for continuous monitoring, mechanical ventilation if respiratory failure develops, renal replacement therapy (dialysis) if the kidneys fail, and ongoing hemodynamic support.

Recovery and Long-Term Effects

Surviving sepsis is not the end of the story. Sepsis survivors can face long-term consequences collectively called “post-sepsis syndrome.” In the year following discharge, sepsis survivors have higher rates of hospital readmission, new functional limitations, cognitive impairment, psychological disorders (PTSD, anxiety, depression), and death compared with hospitalized patients who did not have sepsis.

Physical recovery from sepsis varies widely. Many patients experience profound fatigue, muscle weakness (ICU-acquired weakness), difficulty concentrating, and reduced exercise tolerance for months. Some recover fully within weeks; others have lasting disabilities. A significant share of sepsis survivors are readmitted within a few months, often for recurrent infections.

Cognitive and psychological effects are increasingly recognized. “Brain fog,” memory problems, and difficulty with executive function affect a meaningful proportion of survivors. Depression, anxiety, and PTSD are common and often underdiagnosed. Caregivers of sepsis survivors also experience significant psychological burden. Comprehensive follow-up care – including physical rehabilitation, cognitive assessment, mental-health screening, and chronic-disease management – is essential for optimal recovery. Understanding the financial impact of critical illness can help families prepare for the often-prolonged recovery period.

Prevention

Since sepsis is triggered by infection, preventing infections is the most effective strategy. The CDC recommends several evidence-based prevention measures: stay current on recommended vaccinations (influenza, pneumococcal, COVID-19, and others – an infection prevented is a sepsis case prevented), practice good hygiene (handwashing and proper wound care), manage chronic diseases effectively (well-controlled diabetes reduces infection risk), and seek prompt treatment for infections before they can progress. The CDC’s “Get Ahead of Sepsis” campaign emphasizes knowing the signs and acting fast.

In healthcare settings, infection-prevention programs – including hand-hygiene compliance, catheter-care bundles, surgical site infection prevention protocols, and antibiotic stewardship – have demonstrably reduced healthcare-associated infections and, by extension, sepsis. The CDC’s Hospital Sepsis Program Core Elements, introduced to help hospitals build and strengthen dedicated sepsis programs, reflect how seriously health systems now treat early recognition. If you or a family member is hospitalized, do not hesitate to ask healthcare workers whether they have washed their hands and whether indwelling devices (catheters, IVs) are still necessary.

Antibiotic stewardship – using antibiotics only when needed, choosing the right antibiotic, and taking them as prescribed – is a public-health priority. Antibiotic resistance makes infections harder to treat and increases sepsis risk. Never pressure a clinician for antibiotics for viral infections like the common cold or uncomplicated bronchitis.

Frequently Asked Questions

Is sepsis contagious?

Sepsis itself is not contagious – it is a response to infection, not a transmissible disease. However, the infection that triggers sepsis (pneumonia, MRSA, influenza, etc.) may be contagious. Standard infection-prevention measures – handwashing, covering coughs, and staying away from others when sick – reduce the transmission of infections that could lead to sepsis.

How fast does sepsis develop?

Sepsis can develop rapidly – within hours of an infection worsening – or more gradually over days. The speed depends on the virulence of the infecting organism, the patient’s immune status, and the source of infection. Some patients transition from a seemingly routine infection to septic shock within a day. This is why any infection that seems to be getting worse rather than better – or that is accompanied by the warning signs above – should be evaluated urgently.

Can you survive sepsis?

Yes. The majority of patients who receive timely treatment survive. Survival depends heavily on how quickly treatment is initiated, the patient’s age and overall health, the source and severity of infection, and the presence of antibiotic-resistant organisms. Early recognition and rapid treatment are the most important factors under our control – which is exactly why knowing the warning signs matters.

What is the difference between sepsis and septic shock?

Sepsis is infection-triggered organ dysfunction. Septic shock is the most severe subset of sepsis, defined by the need for vasopressor medications to maintain blood pressure and by elevated blood lactate despite adequate fluid resuscitation. Septic shock indicates that the circulatory system has failed to maintain adequate perfusion to the organs, and it carries a substantially higher mortality than sepsis without shock.

Can sepsis come back?

Having had sepsis does not make you immune to future episodes. In fact, sepsis survivors are at increased risk for new infections and recurrent sepsis, particularly in the first few months after discharge. This elevated risk is related to immune dysfunction after the initial episode, underlying health conditions, deconditioning, and healthcare exposure. Survivors should be vigilant about infection prevention and seek prompt medical attention for new infections.

How is sepsis different from meningitis or other severe infections?

Sepsis is the body’s whole-body reaction to an infection anywhere, while conditions like meningitis refer to a specific infection (of the membranes around the brain and spinal cord). Any severe infection can progress to sepsis. The common thread is urgency: severe infections and sepsis are emergencies, and delaying care can be dangerous.

What You Can Do Right Now

Know the warning signs. If you or a loved one has an infection and develops confusion, rapid breathing, an elevated heart rate, extreme pain, or a feeling of being severely ill, act immediately – do not wait to “see if it gets better.” Tell the emergency department staff you are worried about sepsis. That single statement can trigger a rapid protocol that shaves critical minutes off the time to treatment.

Take infections seriously. Most infections that lead to sepsis start as something common – a urinary tract infection, a skin wound, pneumonia. When these infections are treated promptly and appropriately, sepsis is often prevented. Do not ignore worsening symptoms, skip prescribed antibiotics, or delay seeking care when an infection is not improving.

If you or a loved one has survived sepsis, understand that recovery is a process. Follow up with your primary care clinician within a week of hospital discharge. Discuss a rehabilitation plan. Screen for depression and PTSD. And know that what you are experiencing – the fatigue, the cognitive fog, the anxiety – is a recognized consequence of sepsis, not “all in your head.” Support exists, and recovery, while sometimes slow, is real.

This article is for general education and is not medical advice. It cannot diagnose sepsis or replace emergency care. If you suspect sepsis, call 911 or go to the emergency room and say “I am worried about sepsis.”

Sources

• Centers for Disease Control and Prevention (CDC) – About Sepsis; Get Ahead of Sepsis; Hospital Sepsis Program Core Elements; Sepsis Prevention
• World Health Organization (WHO) – Sepsis fact sheet
• Sepsis Alliance – It’s About TIME; sepsis warning signs in adults and children
• Society of Critical Care Medicine – Surviving Sepsis Campaign International Guidelines and Hour-1 Bundle
• Sepsis-3: The Third International Consensus Definitions for Sepsis and Septic Shock (JAMA, 2016)
• National Institutes of Health (NIH) / MedlinePlus – Sepsis