We have analyzed the Danish national drug directory (Medicine.dk) and found that it provides the information from industrial drug trials instead of the more objective and reliable information on the drugs provided by meta-analyses made by researchers independent of the pharmaceutical industry, like the Cochrane collaboration. The consequence of this is a strong bias, as a large fraction of the drugs are presented more positive and less harmful than they actually are. Whole classes of drugs that in independent meta-analyses have been found to be of little clinical value, or even harmful, are still listed in the national drug directories as beneficial drugs, i.e. anticancer chemotherapy, the anti-depressive drugs, and the anti-psychotic drugs. To solve this serious problem of misguidance, we have identified the core principles for rational listening of data regarding positive and negative effects of the pharmaceutical drugs. An outline of a standard list of positive and negative drug effects is suggested. Information on each drug should be provided with due regard to dose, indication of use, all clinically relevant outcomes, method of drug study used for documentation, including placebo type, and the quality of the study. We recommend the use of Number Needed to Treat (NNT) and Number Needed to Harm (NNH) for each single situation. When more objective and reliable data exist, they should be preferred rather than more doubtful data from studies of lower quality. We warn physicians and patients that the existing drug directory is strongly biased and not a reliable source of information.