OverviewBlood shot eyes can be a sign of drug abuse. The blood vessels on the surface of the eye dilate in response to the use of certain drugs, making the eyes appear red.
Update Date 8/12/2011
Updated by: Linda J. Vorvick, MD, Medical Director, MEDEX Northwest Division of Physician Assistant Studies, University of Washington, School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.