Thanks to the advancements in Social Media, Knowledge Management is evolving to ways of implementation based on active participation of employees and free knowledge sharing. This shift is deemed to allow overcoming some limits of the traditional approach, and especially the ineffective management of tacit knowledge. The KM literature has often analysed the benefits and advantages of Social Media, but less attention has been devoted to their limitations and problems. The paper contributes to this topic by examining an unintended consequence of the use of Social Media: the “cognitive overload” effect.