Up-dosing to 600mg Omalizumab for Chronic Spontaneous Urticaria: More Effective Than 300mg?Short running title: Omalizumab Up-dosing for UrticariaRachel S. Simpson, BScH1, Ariba Quidwai1,2* Jason K. Lee, MD11Toronto Allergists, Toronto, ON, Canada2Western University, London, ON, Canada*Please note Ariba Quidwai has no academic degree achieved at the time of submission.Corresponding Author: Rachel Simpson, Email: rachel.simpson@queensu.ca, Address: 123 Edward St. Suite 920, M5G 1E2, Toronto, ON, Canada, 647-352-2554Conflicts of interest: Jason K. Lee reports receiving research grants, clinical research trial funding, and speaker fees from Novartis, Regeneron, Sanofi, Sanofi Genzyme, AstraZeneca, Genentech, Roche, and GlaxoSmithKline. Rachel S. Simpson does not report any conflicts of interest. Ariba Quidwai does not report any conflicts of interest.Funding Source: This research did not receive any specific grants from funding agencies in the public, commercial, or not-for-profit sectors.Ethics Statement: Study was conducted in accordance with the 2008 Declaration of Helsinki.Keywords: chronic spontaneous urticaria, omalizumab, up-dosing, 600mg, 300mgAbbreviations: Chronic Spontaneous Urticaria (CSU), Immunoglobulin E (IgE), Fragment Crystallizable (FC), Every 4 Weeks (q4wks), Urticaria Activity Scores Over 7 Days (UAS7),Word Count: 598Figures: 0, Tables: 1