Despite extensive research into electronic Word-of-Mouth (eWOM) in the healthcare sector, its impact on patients’ choice of online consultation in Online Health Communities (OHCs) remains largely unexplored. The current study aims to fill this research gap by investigating the heterogeneous effect of different eWOM characteristics on both OHCs and Social Networking Sites (SNSs) from a cross-media perspective. Drawing upon the Elaboration Likelihood Model (ELM) and cognitive cost model, a research model is proposed and hypotheses are examined employing data gathered from 8,472 physicians across two platforms. The findings indicate that both the quality and quantity of eWOM in OHCs positively affects patients’ choice of online selection, eWOM on SNSs is also positively related to patients’ choice. Additionally, eWOM on SNSs negatively moderates the relationship between eWOM quality in OHCs and patients’ choice, while eWOM on SNSs exhibits a U-shape moderating influence on the relationship between eWOM quantity in OHCs and patients’ choice.