_______________________________________________________________________________________________________________________________ Open Access Maced J Med Sci. 2019 Jan 30; 7(2):259-263. 259 ID Design Press, Skopje, Republic of Macedonia Open Access Macedonian Journal of Medical Sciences. 2019 Jan 30; 7(2):259-263. Special Issue: Vietnamese Dermatology https://doi.org/10.3889/oamjms.2019.069 eISSN: 1857-9655 Clinical Science The Efficacy of a Two-Fold Increase of H1-Antihistamine in the Treatment of Chronic Urticaria - the Vietnamese Experience Huyen Tran Thi 1,2 , Lan Pham Thi 1,2 , Thuong Nguyen Van 1,2 , Phuong Pham Thi Minh 1 , Hao Nguyen Trong 3 , Tro Chau Van 4 , Sau Nguyen Huu 1,2 , Trang Trinh Minh 1 , Nghi Dinh Huu 1,2 , Tam Hoang Van 1,2 , Van Tran Cam 1 , My Le Huyen 1 , Khang Tran Hau 1,2 , Thuy Nguyen Thanh 1 , Phuong Hoang Thi 1 , Linh Nguyen Thuy 1 , Marco Gandolfi 5* , Francesca Satolli 5 , Claudio Feliciani 5 , Michael Tirant 6,7 , Aleksandra Vojvodic 8 , Torello Lotti 6 1 National Hospital of Dermatology and Venereology, Hanoi, Vietnam; 2 Hanoi Medical University, Hanoi, Vietnam; 3 HCMC Hospital of Dermato-Venereology, Ho Chi Minh City, Vietnam; 4 Department of Dermatology, Pham Ngoc Thach University of Medicine, Ho Chi Minh City, Vietnam; 5 Unit of Dermatology, University of Parma, Parma, Italy; 6 University of Rome G. Marconi, Rome, Italy; 7 Psoriasis Eczema Clinic, Melbourne, Australia; 8 Department of Dermatology and Venereology, Military Medical Academy of Belgrade, Belgrade, Serbia Citation: Tran Thi H, Pham Thi L, Van TN, Thi Minh PP, Nguyen Trong H, Chau Van T, Nguyen Huu S, Trinh Minh T, Dinh Huu N, Hoang Van T, Tran Cam V, Le Huyen M, Tran Hau K, Thanh TN, Thi PH, Thuy LN, Gandolfi M, Satolli F, Feliciani C, Tirant M, Vojvodic A, Lotti T. The Efficacy of a Two-Fold Increase of H1-Antihistamine in the Treatment of Chronic Urticaria - the Vietnamese Experience. Open Access Maced J Med Sci. 2019 Jan 30; 7(2):259-263. https://doi.org/10.3889/oamjms.2019.069 Keywords: Chronic urticaria; Chronic idiopathic urticaria; Antihistamine; Fexofenadine; Levocetirizine *Correspondence: Marco Gandolfi. Unit of Dermatology, University of Parma, Parma, Italy. E-mail: marco.gandolfi5@gmail.com Received: 02-Jan-2019; Revised: 16-Jan-2019; Accepted: 17-Jan-2019; Online first: 28-Jan-2019 Copyright: © 2019 Huyen Tran Thi, Lan Pham Thi, Thuong Nguyen Van, Phuong Pham Thi Minh, Hao Nguyen Trong, Tro Chau Van, Sau Nguyen Huu, Trang Trinh Minh, Nghi Dinh Huu, Tam Hoang Van, Van Tran Cam, My Le Huyen, Khang Tran Hau, Thuy Nguyen Thanh, Phuong Hoang Thi, Linh Nguyen Thuy, Marco Gandolfi, Francesca Satolli, Claudio Feliciani, Michael Tirant, Aleksandra Vojvodic, Torello Lotti. This is an open- access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0) Funding: This research did not receive any financial support Competing Interests: The authors have declared that no competing interests exist Abstract BACKGROUND: Chronic urticaria, a mast cell-driven condition, is common, debilitating and hard to treat. H1- antihistamines are the first line treatment of chronic urticaria, but often patients do not get satisfactory relief with the recommended dose. European guidelines recommend increased antihistamine doses up to four-fold. AIM: We conducted this study to evaluate the efficacy of increased H1-antihistamine doses up to two-fold in Vietnamese chronic urticaria patients. METHODS: One hundred and two patients with chronic urticaria were recruited for treatment with levocetirizine (n = 52) or fexofenadine (n = 50). Treatment started at the conventional daily dose of 5 mg levocetirizine or 180 mg fexofenadine for 2 weeks and then increased to 10 mg levocetirizine or 360 mg fexofenadine for 2 weeks if patients did not have an improvement in symptoms. At week 0, week 2 and week 4 wheal, pruritus, size of the wheal, total symptom scores, and associated side-effects were assessed. RESULTS: With the conventional dose, the total symptom scores after week 2 decreased significantly in both groups compared to baseline figures, i.e. 7.4 vs 2.3 for levocetirizine group and 8.0 vs 2.6 for fexofenadine group (p < 0.05). However, there were still 26 patients in each group who did not have improvements. Of these 26 patients, after having a two-fold increase of the conventional dose, 11.5% and 38.5% became symptom-free at week 4 in levocetirizine group and fexofenadine group, respectively. At week 4 in both groups, the total symptom scores had significantly decreased when compared with those at week 2 (2.8 ± 1.5 versus 4.7 ± 1.6 in levocetirizine group; 2.1 ± 1.9 versus 5.1 ± 1.4 in fexofenadine group). In both groups, there was no difference in the rate of negative side effects between the conventional dose and the double dose. CONCLUSION: This study showed that increasing the dosages of levocetirizine and fexofenadine by two-fold improved chronic urticaria symptoms without increasing the rate of negative side effects. Introduction Urticaria is an allergic reaction of the skin capillaries to many endogenous or exogenous allergens. This disease can be characterised by the formation of wheals, angioedema or both and can disappear within 24 hours [1]. Patients with urticaria often experience a sensation of itching or burning which can interfere with daily life. Based on chronology, urticaria is divided into acute and chronic. As opposed to acute urticaria, chronic urticaria is defined by recurrent episodes occurring at least twice a week for 6 weeks, possibly lasting for many months, or many years [2], [3], [4]. Urticaria is also classified as spontaneous and inducible with and without any specific eliciting factor involved. Chronic urticaria substantially impacts on a patient’s quality of life with