Aspects of the subject disclosure are directed towards processing search logs and/or other large scale data sources to detect medical related-effects. For example, an anomalous number of queries regarding a particular symptom and a drug may indicate the existence of a previously unknown side-effect of the drug. Side effects of drug interactions may also be found by processing behavioral data such as queries and social network posts. Also described is the generation of symptom spectra data that is processed to detect anomalies and the like in user behavior corresponding to medical related-effects.