Public self-reported adverse experience and knowledge about use of herbal and dietary supplements.

Background: Herbs and dietary supplement (HDS) use has become increasingly used among the Thai population due to greater health awareness and easier product access. However, research on adverse events from HDS and information needs relating to HDS among the Thai population is limited. This study aims to explore use, adverse experiences, self-assessed knowledge and perspectives on HDS among the general public in Thailand.

Methods: A cross-sectional self-administered survey in the general public conducted in 6 public areas in a large city of northeastern Thailand, over 5-month period. It explored experiences relating to use and adverse effects of HDS. Knowledge and information needs relating to HDS were self-assessed by using a visual analog scale and closed questions. The perspectives on HDS were determined using the 5 point-Likert scales for degree of agreement. Participants were selected by purposive sampling.

Results: Of the 1,064 questionnaires distributed, 540 (51.0%) respondents reported using herbal and dietary supplements (HDS). Among them, 363 (67.2%) used herbs, and 423 (78.3%) used dietary supplements, with 40.3% using these products infrequently in the past six months. Common herbs included andrographis (25.3%), turmeric (21.2%), and senna (6.9%), while vitamin C (41.8%), collagen (11.8%), and vitamin B complex (9.0%) were the most frequently used dietary supplements. Adverse effects were reported by 42 respondents, primarily associated with turmeric (25.0%) and vitamin C (31.8%), with most rating the severity as mild (76.2%). Self-assessed knowledge about HDS use and adverse effects was moderate, with a significant demand for information on interactions with medications (59.3%), adverse effects (57.0%), and actions to take if adverse effects occur (52.8%). Higher education levels correlated with increased in knowledge about HDS use and adverse effects (p = 0.007 and p = 0.001, respectively).

Conclusions: Approximately half of the general public in Thailand use HDS, with a small number of reporting adverse events, primarily mild gastrointestinal effects. The public has a moderate level of knowledge about the use and adverse effects of HDS, but there is a need for improved safety knowledge relating to HDS.