Objective: Avoiding injection incompatibilities is important. At our hospital, pharmacists are present at the intensive care unit (ICU),where they manage drip lines and use a lookup table for injection incompatibilities. We assessed the risk of injection incompatibilities in the ICU and the contribution of pharmacists toward their avoidance.Methods: We investigated the number of injections and main drip lines used for outpatients admitted to the general ward and ICU from an emergency setting. We further investigated inappropriate drip line conditions, subsequent interventions by pharmacists, and the actual number of injection incompatibilities. The investigation period lasted 1 year from April 2016 onward.Results: The number of injections and drip lines used in the ICU was significantly higher than that used in the general ward (p<0.001). Patients in the ICU received multiple continuous intravenous injections from one drip line despite the number of main drip lines being high. Even using the lookup table, 78.3% inquiries made by nurses were related to injection incompatibilities. Fourteen inappropriate drip lines selected by nurses were associated with a risk of injection incompatibility; these occurred during the absence of pharmacists and involved a combination of continuous intravenous injections to be administered from a side line. Subsequently,pharmacists intervened and avoided injection incompatibilities. There was no report of injection incompatibilities in the ICU.Conclusion: At ICU, the risk of injection incompatibilities is high and it is necessary to focus on the combination of injections to be administered from main drip lines and side lines as well as incompatibilities of multiple continuous intravenous injections to be administered from side lines. A lookup table is insufficient to avoid injection incompatibilities. Therefore, pharmacists can contribute to avoiding injection incompatibilities by maintaining constant presence in the ICU, designing drip line layouts, and proposing line selections.