IntroductionThe Glasgow Coma Scale (GCS) is an assessment tool commonly used by emergency department (ED) clinicians to objectively describe level of consciousness, especially in trauma patients. This study aims to assess the effect of drug and alcohol intoxication on GCS scores in cases of traumatic head injury. MethodsIn this retrospective chart review study, data were extracted from The Pennsylvania Trauma Systems Foundation Data Base Collection System. Eligible subjects included trauma patients aged 18 years and older, with head trauma, who presented between January 2019 and August 2023. Subjects were matched to controls who did not test positive for drugs or alcohol, matched by Injury Severity Score (ISS) category. ResultsAmong 1088 subjects, the mean age was 63 (95% CI 62–64). The mean Injury Severity Score was 21 (95% CI 21–22). The median GCS among all subjects was 14 (IQR 6–15). Cases with alcohol or drug use were matched to controls without alcohol or drug use, and were matched by categories of Injury Severity Score. Cases with alcohol or drug use had lower GCS (median 13; IQR 3–15), compared to cases without alcohol or drug use (median 15; IQR 13–15) (p < 0.0001, Wilcoxon Rank Sum Test). ConclusionsAmong patients with head trauma, intoxicated patients had statistically significant lower GCS scores as compared to matched patients with similar Injury Severity Scores.