Drug-related visits to the emergency department in a Spanish university hospital.

Background: Negative outcomes of medications (NOMs) are a major public health problem that impact on patients' quality of life. As many NOMs are avoidable, it is necessary to determine their causes in each health setting in order to plan preventive strategies.

Objective: The aims of this study were to assess the frequency, type, severity, and preventability of NOMs that result in emergency department visits, to identify the main medications involved, and to determine factors associated with their development in a general hospital in Spain.