SummaryPoor drug quality is a global concern as it can cause treatment failure, adverse effects, increased morbidity, mortality and development of drug resistance. This study was aimed to identify factors affecting drug quality problems. Odds ratio (OR) and 95% confidence intervals (CIs) were used through a logistic regression model to determine association between 4 M factors (man, machine, materials and methods) and drug quality problems (physical appearance changes, labeling problems, packaging problems and packing problems). We found that two factors, man and material, were mainly associated with drug quality problems. Among other man factors, 'inspector checking the finished products' was the leading cause for labeling problems. Likewise, aluminum foil was responsible for packaging problems among other material factors. We conclude that drug manufacturers should consider using detector and barcode systems to reduce human errors and use good quality packaging materials to reduce drug quality problems.