Aims and methodTo examine the prevalence of head shop drug usage in individuals attending a range of adult mental health services. We examined the effect of head shop drug usage on the mental state of individuals with a range of mental health disorders. Clinical data were obtained from 608 consecutively reviewed individuals attending adult mental health services in relation to their use of head shop and psychoactive drugs and the putative effects of head shop drugs on their mental state.ResultsThe prevalence of head shop drug use was 13% (n= 78), with a higher prevalence of usage noted in individuals younger than 35 years of age (25%). A large proportion of individuals (n= 41, 54%) reported adverse effects of these agents on their mental state, with psychotic symptoms being the most prevalent.Clinical implicationsHead shop drug usage was associated with a reported deleterious effect on mental state, which was particularly evident for individuals with a history of psychosis.