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 8/14/2015
Updated by: Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.