Primary hypotensive transfusion reaction (HTR) is a decrease in blood pressure of 30 mm Hg or more that occurs within minutes of a transfusion initiation, without another evident cause of hypotension. Blood pressure returns to baseline when the transfusion is discontinued. HTR is a diagnosis of exclusion, after eliminating other reactions that may cause hypotension, such as TRALI, AHTR, anaphylaxis, and sepsis. The condition is not usually life-threatening.