A processor is to monitor social media for links between a drug and an adverse drug reaction (ADR), and to extract a relation between the drug and the ADR using named entity recognition to provide a weighted social media relation between the drug and the ADR. The weighted social media relation is based on a confidence of a link between the drug and the ADR. A domain knowledge of ontologies of drug names and/or ADRs is used to refine the weighted social media relation and to quantify the weighted social media relation by using drugs and ADR links extracted from research publications and/or from clinical trial reports, to provide a research weight for the weighted social media relation; and/or by using a search engine to search the Internet for the drug and the ADR, where a number of hits quantifies an internet weight for the weighted social media relation.