Intravenous immunoglobulin (IVIg) is a solution of human IgG, salt, sugars and solvents, which is used to treat a multitude of diseases. Although IVIg has been known to treat many diseases safely and successfully, there are relatively few supporting randomized controlled trials. In this article, we review the biological mechanisms of IVIg in dermatological disorders and the practicalities of its use, including its mechanism of action, dosing, availability, costs and adverse effects.