2025 Volume 118 Issue 2 Pages 135-140
Fixed drug eruptions are characterized by the repeated development of round or oval erythematous lesions and edematous changes at the same site after administration of the causative drug. Localized redness, irritation, burning, and itching occur after 30 minutes to several hours of oral administration of the causative drug. In severe cases, the eruptions progress to Stevens-Johnson syndrome and toxic epidermal necrolysis, which are potentially life-threatening. Common sites are the skin on the hands and feet, and mucocutaneous junctions such as the lips and vulva. Since mucosal lesions, such as in the buccal or pharyngeal mucosa, sometimes occur, it is necessary to differentiate the condition from infectious diseases, inflammatory diseases, autoimmune diseases, etc.
We encountered two strongly suspected cases of fixed drug eruption with lesions confined to the oral cavity. Both cases showed a relatively rapid course, with erythematous lesions accompanied by swelling and pain observed on the lips and oral mucosa. There were no lesions at any other sites and no history of similar symptoms in either case. A dermatologist suspected fixed drug eruption in both cases, even though fixed drug eruptions associated with lesions only on the lips and oral mucosa are relatively rare. However, it is also difficult to make a definitive diagnosis of fixed drug eruption in patients presenting with only mucosal lesions. Fixed drug eruption may progress to SJS or TEN if ingestion of the causative drug is continued. Therefore, it is important to recognize the possibility of drug eruption at an early stage and make an early diagnosis/administer prompt and appropriate treatment in cooperation with a dermatologist.
