Recently, westernized diet and lifestyles have led to obesity and various adult diseases resulting in a negative influence on the quality of life. There has been an increased interest in choosing proper diet and regular exercise in order to lead a healthy life. The number of people looking for dietary supplements has increased steadily. Dietary supplements are products intended to help maintain or improve the health of consumers. However, if customers take dietary supplements excessively, they may be harmful due to side effects, misuse, abuse and overdose. I performed a toxicologic review of the dietary supplements, glucosamine and chitosan, which are widely used in the country in order to provide the proper understanding of safety of these products.