Background: Prescribing medications is one of the most common medical decisions that is made by primary care providers (PCPs). In the Republic of Croatia, PCPs hold a key position in prescribing and evaluating the medications that are provided for patients. Accordingly, providing advice for patients regarding the potential adverse drug reactions (ADRs) and drug-drug interactions (DDIs) is frequently the responsibility of the PCPs. The aim of the current study was to assess the knowledge, attitudes, and counseling practices of PCPs regarding drug interactions and adverse effects. Methods: After enrolling 195 PCPs that were selected at random, a survey was conducted while using an anonymous questionnaire that was created based on previously published studies, adjusted in a way that includes the most commonly prescribed medications in Croatia. Results: Of the 10 questions on knowledge about DDIs and ADRs, the median number of correct responses by PCPs was 5 (interquartile range 4 to 7). More than half of respondents (56%) agreed with the claim that knowledge of drug side effects facilitated their work in family medicine. Almost all of the respondents (92.8%) explained side effects and drug interactions to special groups of patients (pregnant women, elderly patients etc.). Conclusion: The results show a need for additional education in the field of drug prescribing. However, PCPs were aware of the importance of counseling practices about adverse drug reactions and interactions and counseling practices among special patients populations are satisfactory.