Introduction: Medication process has a significant impact in treatment of patients. This process includes four stages: Prescribing, Transcribing, Dispensing and Administration. Medication errors are minatory challenges for patient safety in all countries that can cause serious problems for patients.

Aim: This study has been conducted with the aim of review and classification of the literature related to medication errors and also identification of contributing factors in medication errors.

Method: In the present study a systematic review of the literature related to medication process errors was conducted using the following databases: Embase, Medline, Pubmed. Inclusion criteria were that the studies assessed or discussed the incidence of medication errors and contributory factors to medication errors during the medication treatment process in adults or in children. In this way, literature related to criteria has been investigated and classified in the present study.

Result: In this paper 70 articles have been examined. 17 of them (24%) focused on prescribing errors, 5 of them (7%) focused on transcribing errors, 9 of them (13%) measured dispensing errors, 9 of them (13%) measured administration errors and finally 30 interventional studies assessed actions for reducing medication errors. It has been found that wrong dose, wrong frequency and wrong drug were the most common errors in prescribing stage of studies.

Conclusion: utilization of Computerized Physician Order entry with decision support system was the most action for reducing medication errors. In addition, poor knowledge of medicines was identified as a contributory factor for errors by both doctors (prescribers) and nurses (when administering drugs).