How should I differentiate between a mild allergic reaction and a more serious transfusion reaction?

To differentiate between a mild allergic reaction and a more serious reaction, such as anaphylaxis, the key is the presence of systemic, life-threatening features affecting the airway, breathing, or circulation ¹,².

A mild allergic reaction typically presents with skin changes like urticaria (hives), angioedema (swelling), or erythema (redness) without any systemic features ¹. These reactions usually occur within an hour of exposure ¹.

A more serious reaction, specifically anaphylaxis, is a severe, life-threatening, generalised or systemic hypersensitivity reaction ². It is characterised by rapidly developing, life-threatening problems involving the airway (such as pharyngeal or laryngeal oedema), breathing (such as bronchospasm with tachypnoea), and/or circulation (such as hypotension and/or tachycardia) ². In most cases, these severe reactions are also accompanied by skin and mucosal changes like erythema, urticaria, or angioedema, alongside hypotension and/or bronchospasm ¹,². The onset of such reactions is usually less than 1 hour after exposure ¹. Recognising these systemic signs is crucial for identifying a serious reaction that requires immediate attention ¹,².