Objective: Polypharmacy is common among the elderly patients. The aim of this study was to determine drugs used inappropriately in elderly with polypharmacy or causing a dangerous drug combination (DDC) and to investigate the relation between drug interaction and emergency department (ED) presentation symptoms.

Methods: This prospective study was performed with elderly patients aged over 65. Patients’ demographic characteristics, presentation symptoms, comorbid diseases, and the names, numbers, dosages and side-effect of drugs used were recorded.

Results: DDC was present in 94.6% of patients, and 24.3% presented to the ED with drug interaction-related symptoms. The mean age of the patients with DDCs was 72.4±6.7 years, 68.3±5.5 years among those without DDC(p=0.016).The most common comorbid disease was hypertension(75.1%), the most commonly used drug group was anti arrhythmics (15.4%),and the most commonly used medication was aspirin(6.5%). The relation was observed between drug interaction-related presentation symptoms and coronary artery disease (CAD) (p=0.044). Correlation was determined between DDC and the anti-hypertensive drug group (p<0.001).Correlation was determined between drug interaction and subjects with presentation symptoms of dyspnea and bleeding (p<0.001 and p<0.001, respectively). Numbers of drugs used and frequency of presentation to hospital were higher in patients with DDCs (p<0.001; 0.040 respectively).Positive correlation was determined between frequency of presentation and number of drugs used(r: 0.514; p <0.001).

Conclusion: DDCs are more common as age increases in elderly. This situation especially remarkable in subjects with CAD and antihypertensive drugs users. Presentations to hospital caused by drug-drug interactions most commonly involve dyspnea and bleeding, and a higher number of drugs increase rates of DDC development and numbers of hospital presentations.