The amount of online medical information is constantly increasing. Studies have shown that internet users tend to increasingly use the Web to find health information. Getting the right information for users is crucial, as it can have a direct outcome on their health. In this talk, I will illustrate through a few research projects how data mining and information retrieval can help patients better understand their health condition. I'll first describe two data mining project carried out on health data: opinion mining for drugs, and automatic summarization of medical documents. Then I will introduce my current research on information retrieval, including resource creation for evaluation, and query processing.