OBJECTIVE: To analyse safety risks in injectable medications. To assess the potential impact and pharmacoeconomic aspects of safety tools. DESIGN: The injectable drug process was prospectively assessed using a failure modes, effects and criticality analysis. Criticality indexes were estimated based on their likelihood of occurrence, detection probability and potential severity. The impact of 10 safety tools on the criticality index was calculated and extrapolated to all drugs injected daily. Yearly costs for a reduction in criticality by 1 point (=1 quali) per day were estimated. SETTING: Paediatric and neonatal intensive care units in a University Hospital. PARTICIPANTS: Two paediatric nurses, a neonatologist, three hospital pharmacists. INTERVENTIONS: Qualitative and quantitative risk assessment. MAIN OUTCOME MEASURES: Failure modes, criticality indexes, cost-efficacy ratios. RESULTS: Thirty-one failure modes identified, with the mean of their entire criticality indexes totalling 4540. The most critical failure mode was microbial contamination. The following gains were predicted: 1292 quali (46 500 per day by extrapolation) from ready-to-use syringes, 1201 (72 060) by employing a clinical pharmacist, 996 (59 780) from double check by nurses and 984 (59 040) with computerized physician order entry. The best cost-efficacy ratios were obtained for a clinical pharmacist (1 quali = 0.54 euros), double check (1 quali = 0.71 euros) and ready-to-use syringes (1 quali = 0.72 euros). Computerized physician order entry showed the worst cost-efficacy ratio due to a very high investment costs (1 quali = 22.47 euros). CONCLUSION: Based on our risk and pharmacoeconomic analyses, clinical pharmacy and ready-to-use syringes appear as the most promising safety tools.