Irritational fibromas are reactive lesions by which the body defends itself against constant irritation. It is most commonly observed in old age groups. This is mainly attributed to irritation by ill-fitting prosthodontic appliances. However, in the herein demonstrated case report, we present a case of a young adult who suffered from a giant irritational fibroma arising from the upper labial mucosa. The lesion had a history of starting 15 years earlier. Further history indicated the cause to be a childhood trauma to deciduous teeth. The size of the lesion was unexpectedly large compared to the classical picture of reactive lesions. The case received the appropriate investigations through radiography and biopsy; together with history and staged treatment planning, the case was successfully managed. The report emphasizes the important role of detailed history in reaching a diagnosis. It also clarifies that it is not the size of the lesion that differs for the diagnosis, but it is rather the clinical behavior.