This study analyzed 639 responses from an online health forum, identifying five main themes: diagnostic, experiential, informational, peer relations, and relationships with healthcare professionals. Of the 298 diagnostic responses, 5% were based on guideline evidence, 6% contained partly evidence-based information, and 10% were non-evidence-based and potentially dangerous. Experiential responses constituted 10%, with 23% offering advice unsupported by clinical evidence, and 46% directing users to other online resources or healthcare professionals.