Objective To evaluate the evidence for double checking the administration of medicines.

Design A systematic search of six electronic databases—Embase, Medline, British Nursing Index and Archive, CINAHL, National electronic library for Medicines (NeLM) and PsycINFO—for all articles describing double checking of medication and dose calculation, for either dispensing or administration in both adults and children up to and including October 2010.

Results Sixteen articles met the inclusion criteria. There were only three quantitative studies. Only one of these was a randomised controlled clinical trial in a clinical setting. This study showed a statistically significant reduction in the medication error rate from 2.98 (95% CI 2.45 to 3.51) to 2.12 (95% CI 1.69 to 2.55) per 1000 medications administered with double checking. One study reported a reduction in dispensing errors, by a hospital pharmacy, from 9.8 to 6 per year following the introduction of double checking. The majority of the studies were qualitative and involved interviews, focus groups and questionnaires.

Conclusion There is insufficient evidence to either support or refute the practice of double checking the administration of medicines. Clinical trials are needed to establish whether double checking medicines are effective in reducing medication errors.