A vesicle, or blister, is a thin-walled sac filled with a fluid, usually clear and small. Vesicle is an important term used to describe the appearance of many rashes that typically consist of or begin with tiny-to-small fluid-filled blisters.
Review Date 4/16/2019
Updated by: Michael Lehrer, MD, Clinical Associate Professor, Department of Dermatology, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.