Objective: In this study an analysis was made of suspected drug-related side effects with the active substance sildenafil received at the Agency for Medicinal Products and Medical Devices (HALMED) in the period from 21 March 2009 to 20 April 2020. Patients and Methods: The Agency for Medicinal Products and Medical Devices (HALMED) was requested to provide information on suspected side effects for medicine containing the active substance sildenafil reported in Croatia. From the obtained data, the age and sex of the patient, the profession of the reporters, the severity of the adverse reaction and the adverse reactions listed according to the MedDRA classification by organ systems were analyzed. Results: In the observed time period, a total of nineteen suspected adverse reactions were reported, of which fifteen cases were reported by males. Of the total number of reports, nine (47.37 %) were characterized as serious side effects. Doctors reported 47.37%, pharmacists 31.58%, patients 15.79%, and other health professionals 5.26% of suspected side effects. Most patients belong to the age group of 30 to 70 years (73.68%). According to the MedDRA classification, the most suspected side effects were related to the group of nervous system disorders (18.37%), cardiac disorders (16.33%) and general disorders and reactions at the site of application (14.29%). Conclusion: Side effects are mostly reported by doctors for male patients, of which 40% are serious. Given that the number of reports since 2009 is only nineteen, healthcare professionals and patients should be encouraged to report suspected adverse drug reactions more frequently.