Inclusion Criteria:  HK resident able to read/communicate in Cantonese/Putonghua. This may exclude potential subjects from other countries with higher alcohol consumption than local Chinese, but quality of the chat-based intervention is important for the research hypothesis, and it will not be feasible to recruit other language speakers (e.g., English) in the present study. Aged ≥18 with proficiency in using IM Apps (e.g., WhatsApp, WeChat). Those aged <18 are excluded as other studies suggest they have different patterns of alcohol drinking and reduction from adult drinkers.  Exclusion Criteria:  Those unable to understand or receive face-to-face ABI due to severe traumatic injury, unconscious, or drunk patients unable to follow commands Anticipated to be admitted to in-patient department for >1 week, which will interfere with the chat-based intervention Having psychiatric/psychological diseases or receiving regular psychotropic medication Participating in other alcohol reduction or abstinence programmes