Background: One of the potential threats to patient safety is the sharing of medication among patients, which is form of self-medication. This project analyzed frequency, perception of risks and factors associated with sharing prescription analgesics. Methods: For this project we were conducted two qualitative and a cross-sectional research. The first qualitative study was conducted by semi-structured interviews among 15 PMPs employed in Croatian pain clinics. Second qualitative study was conducted by focus group discussions with 40 participants. Adults aged ≥18 years who had received a prescription for an analgesic at least once in a lifetime were included. Six separate focus groups were conducted to discuss participants’ perception of risks associated with sharing of prescription analgesics among patients. Additionally, participants filled out two questionnaires on demographic data, their own behavior regarding sharing analgesics, and their attitudes about risks associated with sharing prescription analgesics. A cross-sectional study was conducted in 10 outpatient family medicine practices in Croatia amongst 1000 patients to whom their physicians have prescribed analgesics at least once in their lives. A questionnaire was used to collect data about patients’ pain intensity, prescription analgesic sharing habits, factors associated with this behavior, perception of risks associated with the conduct and demographic data. Logistic regression was conducted to analyze independent factors associated with lending and borrowing prescription analgesics. Results: Among PMPs, twelve have seen patients who share their prescription analgesics with other patients for whom prescription is not intended. Most PMPs consider prescription analgesics sharing a risky and negative behavior. In second qualitative study in a questionnaire, 55% of the participants indicated that they personally shared prescription analgesics, while subsequently in the focus group discussions, 76% confessed to such behavior. Participants recognized certain risks related to sharing of prescription analgesics, mentioned a number of reasons for engaging in such behavior, and indicated certain positive aspects of such behavior. In the cross-sectional research we found that 61% of patients in family medicine practices engage in sharing prescription analgesics, whether it was lending (42%) and/or borrowing (54%). Independent predictors of lending prescription analgesics were as follows: history of sharing prescription medication other than analgesics, providing information regarding the medication alongside the prescription medication itself, not reading package insert that accompanies medication, subjective perception of personal health and decreased awareness of personal harm associated with prescription analgesic sharing. Independent predictors of prescription analgesic borrowing were as follows: younger age, communicating details regarding the medication that was given, scanning of package insert accompanying the medication, biased subjective perception of personal health and perceiving alternative medicine as a safer option over conventional medicine. Conclusion: Sharing prescription analgesics is highly prevalent amongst patients in family medicine. Patient education and more involvement of physicians in identifying this behavior were cited as potential remedies for preventing sharing of prescription analgesics. Preventive interventions should be conceived and established.