On the creation of a clinical gold standard corpus in Spanish: Mining adverse drug reactions.

•Creation of a gold standard of electronic health records in Spanish.•Annotation of diseases, drugs and adverse drug reaction (ADR) events.•Quality: inter-annotator agreement of 90.53% for entities and 82.86% for events.•Development and assessment of linguistic analyzer for medical texts.•Automatic ADR extraction with machine learning shows the potential of the corpus.