Public knowledge and factors associated with inappropriate analgesic use: a survey in Thailand Woranuch Saengcharoen a , Nutdaporn Buasri a , Boonyisa Khantapokha a and Sanguan Lerkiatbundit b Departments of a Clinical Pharmacy and b Pharmacy Administration, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Songkhla, Thailand Keywords analgesic; factor; inappropriate use; knowledge Correspondence Asst Prof Dr Woranuch Saengcharoen, Department of Clinical Pharmacy, Faculty of Pharmaceutical Sciences, Prince of Songkla University, Hat Yai, Songkhla 90110, Thailand. E-mail: woranuch.s@psu.ac.th Received July 17, 2014 Accepted May 26, 2015 doi: 10.1111/ijpp.12201 Abstract Objective This study aims to evaluate knowledge of analgesics and factors associ- ated with inappropriate analgesic use among the public. Methods The cross-sectional study was carried out in one large city in the south of Thailand. The survey was conducted using interview of people of age 16 or older. The questionnaire elicited information regarding knowledge, attitudes and behav- iours on analgesic use including prevalence of taking paracetamol >4 g/day (overdosage) and not taking non-steroidal anti-inflammatory drugs (NSAIDs) with meals (inappropriate taking). Key findings Of 1982 participants, paracetamol overdose (n = 595) and inappro- priate NSAID users (n = 751) were less likely to give correct answers about analgesics compared with appropriate users. The overdose use was inversely associated with knowledge on paracetamol (odds ratio (OR) 0.90; 95% confidence interval (CI), 0.83, 0.98) but directly associated with positive attitudes towards high dose taking (OR 2.15; 95% CI, 1.49, 3.11), and high frequency of analgesic use (OR 1.78; 95% CI, 1.24, 2.54). Inappropriate NSAID ingestion was inversely associated with knowledge on NSAIDs and directly associated with more commonly obtaining analgesics from community pharmacies (OR 0.87; 95% CI, 0.82, 0.92 and OR 1.27; 95% CI, 1.01, 1.61, respectively). Conclusions Poor knowledge, positive attitudes towards high dose or high fre- quency of analgesic consumption and the patterns of using drugs were associated with inappropriate analgesic use especially that of paracetamol. Introduction Self-medication with nonprescription drugs such as analge- sics and flu medicines has risen both in developing and devel- oped countries. [1–4] Analgesic agents have been reported as one of the drug classes most commonly associated with drug- related problems including adverse drug reactions. [5] Analgesics such as paracetamol and non-steroidal anti- inflammatory drugs (NSAIDs) are commonly used world- wide. In 2008, 67.2% of the Thai public aged 15 or above used these medications and the prevalence of analgesic usage increased with age. [6] In Thailand, paracetamol is a non- prescription medicine that can be purchased from pharma- cies or retail outlets, whereas nearly all NSAIDs are pharmacist-only medicines that pharmacists can dispense as necessary without a prescription. Paracetamol is relatively safe when taken in therapeutic dose (≤4 g/day for adults). However, overdosage leads to hepatotoxicity and also nephrototoxicity. [7–9] NSAIDs can result in gastrointestinal (GI) complications, ranging from dyspepsia to peptic ulcer and GI bleeding. The recommended dose of NSAIDs on the package label generally relates to GI injury that is minimised by taking with meals. [10,11] Inappro- priate administration such as high dosage or multiple NSAIDs increases the risk of GI events. [12,13] Furthermore, high dose of NSAID use is associated with morbidity involv- ing hepatic, renal and cardiovascular injuries. [14] Numerous studies have assessed the general public’s knowledge of and/or attitudes towards the use of analgesics, such as paracetamol or NSAIDs. [15–17] However, there is little information on the association between factors such as knowledge, attitudes or patterns of taking and inappropriate International Journal of Pharmacy Practice Research Paper International Journal of Pharmacy Practice 2016, 24, pp. 22--29 © 2015 Royal Pharmaceutical Society International Journal of Pharmacy Practice 2016, 24, pp. 22–29