Prevalence and Factors associated with acute adverse events from over-the-counter Chinese Herbal Medicines: A population-based survey of Hong Kong Chinese adults

Background: Over-the-counter proprietary Chinese medicine (pCM) is one of the fastest growing segments of the global pharmaceutical market. Population-based studies of pCM adverse drug reactions, however, have not been undertaken. Methods: A cross-sectional telephone survey was conducted among 1100 Hong Kong Chinese adults in 2011. The past-year prevalence of pCM-related adverse events is examined along with the associated factors. Results: Of respondents, 71.7% reported past-year pCM use with 2.3% reporting pCM-related adverse events (3.2% of pCM users) for which almost one-third required treatment by a health care professional. Among those reporting adverse events, allergic reactions (40.7%), dizziness (18.5%), and gastro-intestinal problems (14.8%) were the most commonly reported acute adverse reactions. Pills/capsules were the form of pCM that caused the highest proportion of adverse events (37%) followed by plasters/dressings (25.9%), creams/ointments (18.5%) and powders (11.1%). PCM users reporting adverse events were more likely to possess lower education levels and have received pCM information from books and mass media sources such as TV and magazines. Pervasive knowledge gaps and low levels of perceived susceptibility to adverse events were shown across pCM users. Package labels were felt to be unclear by 38.7% of users and the main barriers to greater information seeking were the belief that reliable pCM information is unobtainable from Western medical doctors (73%) or pharmacists (67.6%). Conclusions: Previous pCM studies had missed the majority of adverse events. Although governments around the world are moving towards more stringent pCM regulation, lack of access to reliable pCM information and pervasive pCM misconceptions present an ongoing challenge for the safe use of pCM.