Undesired side-effects and toxicities of drugs, especially in the area of new-drug development, are negligibleless, unpredicable and often disastrous once being encountered. Increasing varieties of evidence suggest that the differences of chemical structures of drugs and humans genomic makeup and environmental causes totally decide the occurrences of side-effects and toxicities of drugs instead of chemical structures of a drug alone. The side-effects of central neural systems are relatively easy to be observed and conspicuous and sensitive to judgments with or by fixed grading systems. It could be an important area to systematically study the side-effects of drugs and underlying genetic mechanisms and relationships in between. This review discusses this issue through careful analyzing relevant clinical evidence and published data relating to genetic detection of suffered patients and gives further suggestions to improve.