Sepsis and septicemia are both used to refer to an infection in the blood that can lead to severe side-effects and can be lethal. However, the two terms are not exactly the same in a clinical sense.

Sepsis is a condition where a localized infection causes a systemic response in the body. It is defined by specific criteria such as an elevated temperature, elevated heart rate or abnormal blood test. If left untreated, sepsis may turn to septic shock, fatal in up to 40% of cases. 

Septicemia specifically refers to an infection of the blood. Frequently, a localized infection spreads to the bloodstream (septicemia) which causes a systemic reaction such as fever, elevated heart rate, drop in blood pressure (sepsis). Realize sepsis involves a constellation of symptoms. Fever alone or elevated heart rate alone does not define sepsis.