Stevens Johnson Syndrome-Toxic Epidermal Necrolysis Overlap Secondary to Interaction Between Methotrexate and Etoricoxib: A Case Report.

Rheumatoid arthritis (RA) is an autoimmune disease affecting about 1% of people, with the highest incidence between 40 and 70 years. Methotrexate is an anti-folate analogue that has good efficacy and safety in the treatment of RA. Methotrexate (MTX) and non-steroidal anti inflammatory drugs are often concomitantly administered in clinical practice for the treatment of RA. In this case report, a 57-year-old female was treated with oral methotrexate 7.5 mg per week for a diagnosed case of RA. Since her pain persisted after completing six weeks of treatment with methotrexate, oral etoricoxib 60 mg once daily was added to the treatment regimen. Six weeks later, the patient complained of oral ulcerations and blisters on all fours limbs and trunk. The patient was re-evaluated and was diagnosed with Stevens-Johnson syndrome-Toxic epidermal necrolysis (SJS-TEN) overlap. This case highlights the possible pharmacokinetic interaction between methotrexate and etoricoxib that has a significant clinical implication.