A case of recalcitrant chronic urticaria successfully controlled by warfarin

We describe a case of recalcitrant chronic urticaria successfully controlled by warfarin. A 53-year-old female had suffered from urticaria and angioedema for 6 months. She had been treated with antihistamines, H2-receptor antagonist, leukotriene receptor antagonist, diaminodiphenyl sulfone, prednisolone, and cyclosporine; however, no medicine suppressed the urticaria. Previous reports have demonstrated that thrombin protein synthesis is enhanced in patients with chronic urticaria. Moreover, warfarin, which inhibits the synthesis of thrombin and coagulation proteins, has been reported to suppress urticaria. Based on these findings, the patient was administered 1 mg per day of warfarin in addition to cyclosporine, olopatadine, and the H2-blocker famotidine. Three days later, the dose of warfarin was increased from 1 to 2 mg per day, and it was subsequently increased by 1 mg every week. The prothrombin time international normalized ratio (PTINR) was maintained at around 1. 3 when she was administered 4 mg per day of warfarin. At the start of warfarin administration, the UAS7 score, which was originally defined at our institute, was 42 points. Notably, the UAS7 decreased to 7 points 25 days later, upon the administration of 4 mg per day of warfarin. Subsequently, this score dropped to 0. Cyclosporine was discontinued at the 30th week, and subsequently warfarin was stopped at the 50th week, followed by the discontinuation of famotidine and olopatadine. During 14 months after the end of the treatment, there was no relapse of any symptoms, such as itching, erythema, or wheals. The present case report demonstrates the effectiveness of warfarin treatment for recalcitrant chronic urticaria.