Abstract summary There is a lack of consensus on the safety of the coadministration of drugs and red blood cells (RBCs). A systematic review was undertaken to establish the evidence base for this question and assess how the evidence may be translated into present clinical day practice. Comprehensive searches of MEDLINE, EMBASE, CINAHL, the Cochrane Library and hand searching of transfusion journals, guidelines and websites identified 12 relevant papers: 11 in‐vitro experiments and 1 case report.