Aims: With the progress made in the treatment of cardiovascular patients, the use of anticoagulants such as warfarin, aspirin, ticlopidine, etc. have increased. This study aimed to investigate the frequency of use of warfarin-interfering drugs in warfarin toxicity patients admitted to the emergency ward of Imam Reza Hospital, Mashhad, Iran, from March to August 2016. Materials and Methods: In this original cross-sectional study after obtaining the approval of the university's ethics committee, 133 patients with warfarin toxicity admitted from March to August 2016 were included in the study. The hospital records of the patients were reviewed, and based on the detailed history taken from the patients the information related to the simultaneous use of different drugs, the duration of warfarin use, the reasons for warfarin use, and the symptoms of warfarin toxicity were extracted. SPSS version 24 software was used for data analysis (p<0.05). Results: Artificial heart valve was the most common indication for warfarin use (48%). Potentially fatal bleeding occurred in 85% of patients, and gastrointestinal bleeding was the most common symptom of warfarin toxicity (37.6%). The most common drugs used were aspirin (62.4%), metoprolol (33.1%), and statins (28.8%). Conclusion: In this study, a high frequency of drug interactions with warfarin was observed, which seems to play a significant role in the occurrence of warfarin toxicity. The most common drug interactions were observed in the simultaneous use of aspirin, metoprolol, and statins. Careful monitoring of the type of drugs used by patients is extremely important in providing safe and effective treatment and reducing side effects.