Aims: Information provided on glass labels may be an effective method to reduce alcohol consumption. The aim of this study was to assess the impact of glass labels conveying unit information and a health warning in reducing ad libitum alcohol consumption. 

Methods: A cluster randomised experimental study was conducted to measure the efficacy of a labelled glass in reducing alcohol consumption in a semi‐naturalistic bar‐laboratory setting, in a sample of 81 pairs (n = 162) of UK young adult drinkers. Pairs were randomised to receive two 340 ml glasses of beer or wine: labelled or plain (control). Alcohol consumption was assessed in an ad libitum drinking period and urge to drink was measured at baseline and post drinking period. Focus groups (n = 2) were conducted and thematic analysis was used to gain an insight into the acceptability and the perceived effectiveness of the glasses. 

Results: Mean unit consumption was 1.62 (SD ± 0.83) units in the labelled glass condition and 1.69 (SD ± 0.82) units in the non‐labelled glass condition. There were no significant effects of the labelled glasses on ad libitum alcohol consumption (95% CI ‐0.25 to 0.37, p = 0.35), despite participants (85%) noticing the information. Qualitative analysis of focus groups indicated that although participants perceived the glasses as a useful tool for increasing awareness of units and guidelines, they were viewed as limited in their potential to change drinking behaviour due to the unappealing design of the glass and a view that unit guidelines were not relevant to drinking patterns or contexts. 

Conclusions: Labelled glasses did not change alcohol consumption in the current study, potentially due to ineffectiveness of this type of message in a young adult population. The information on the glasses was attended to, highlighting that glasses could be a feasible tool for providing information.