What is the most common cause of sepsis?

The most common cause of sepsis is a bacterial infection, often starting in the lungs, urinary tract, skin or abdomen. Sepsis occurs when the body's response to infection begins to injure its own tissues and disrupt normal organ function.

Pneumonia, a urinary tract infection and cellulitis are examples of infections that can progress to sepsis. The original infection may cause fever, chills, pain or a wound, but sepsis can also produce a sudden feeling of being very unwell, weakness, confusion or unusual sleepiness. It is the body's worsening response, not the location alone, that makes sepsis an emergency.

If sepsis is suspected, seek urgent medical care rather than waiting for symptoms to settle. Tell the clinician when the illness began, where infection may be located, recent procedures, current medicines and any long-term conditions. Hospital assessment may include vital-sign checks, blood tests, cultures and treatment aimed at the infection and affected organs.

Get emergency help for confusion, difficulty breathing, fainting, mottled or bluish skin, very little urine, a rapidly worsening illness, or severe weakness with fever or chills. Babies, older adults, pregnant people and those with weakened immunity may become seriously ill with less typical symptoms.

Ask where the infection may have started, how organ function is being checked, which treatment is needed, what warning signs to watch for, and when follow-up should occur after recovery.