From a discourse analytic framework, the article analyses health blogs and patient’s forum discussions in which parents to children with congenital heart defects recontextualize medical professional knowledge and share their own experiences. The study show how the two types of online media may serve as a means for parents to attain expert status in their own case by sharing lay knowledge expressed as an amalgamation of the two key perspectives – professional and experienced – as an indivisible unit. Monological discourses, such as narrating, in blogs and more direct and immediate responses in forum discussions are noted as examples of differences in how medical facts are explained and negotiated, how advice is provided and how patient expertise is created. The study also show how blogs and especially forum discussions are used to problematize the validity of actions and opinions of medical staff. The role of developing patient expertise in epistemic communities online may therefore come with a risk of spreading misrepresentation of medical cases.