The prospective design of this study, sample size, and randomization increases the likelihood that our estimates are accurate and increase the generalizability of our findings. Most DRPs attributed to hospital admissions or visits were avoidable. Direct patient contact with pharmacist and family physician was beneficial in providing a safe and effective therapy. Corrective, preventive and educational strategies should concentrate on the most frequently reported populations, diseases and medications. The study addresses the proper use of medications to ensure the best outcomes of pharmacological interventions. Finally, more studies with longer duration focusing on DRPs in Saudi Arabia are needed.