Background: Epinephrine can relieve severe symptoms of urticaria. There has been no previous study on the continuous infusion of epinephrine in uncontrolled acute urticaria. Objectives: This study was aimed to assess the efficacy and safety of continuous infusion of low-dose epinephrine for severe acute urticaria. Methods: From August 2010 to July 2014, 34 severe acute urticaria patients who were uncontrolled symptoms by conventional treatment, were treated with continuous infusionof low-dose epinephrine. They received 1mg epinephrine HCl mixed with 1L of normal saline for 40cc/hour. Blood pressure were checked on 0, 30, 60 and 90 minutes after onset of epinephrine. Results: Low-dose epinephrine significantly improved the clinical symptom. The mean duration of clinical symptom after epinephrine was 3.64 days. Adverse effects were observed in 2(5.8%) patients, and were palpitation & chest discomfort. The average variation of blood pressure after continuous infusion of epinephrine was -3.23mmHg. There were no significant side effects to suggest stopping epinephrine injection. Relapse of urticaria after injection of epinephrine was occurred at 1(2.9%) patient. Of the 34 patients who were followed for at least 1 month after completion of epinephrine injection, 31(91.1%) patients weresymptom free, and 3(8.8%) patients used antihistamine. Conclusion: This study shows that continuous injection of low-dose epinephrine is an efficacious and safe treatment option for treating acute urticaria.