<p>Medication history is a series of data for each patient recorded by pharmacists in daily clinical practice in Japanese pharmacies. This real-world data potentially contains useful information on various risks induced by drugs; however, this information has rarely been used. Therefore, we aimed to verify whether medication histories can be used for drug-induced risk assessment by comparing them with known events as references. To this end, we chose previously reported large-scale trials indicating that anticholinergic drugs for overactive bladder (OAB) are associated with the risk of inducing dementia. We referred to these studies and conducted a retrospective study based on the medication histories of 172,958 patients aged 55 years or older visiting a community pharmacy. Six drugs for OAB (oxybutynin, propiverine, tolterodine, fesoterodine, solifenacin, and imidafenacin) were tested for their risk of inducing dementia, which was determined at the start of using one of the four drugs for dementia (donepezil, galantamine, rivastigmine, and memantine). The association between OAB medications and dementia was assessed using odds ratios (ORs) and 95% confidence intervals (95% CIs). The analysis included 2,634 patients in the case group and 170,324 patients in the control group. A significant difference was observed between the case and control groups (OR, 2.12; 95% CI, 1.66–2.67), indicating that anticholinergic drugs increased the risk of developing dementia. The results were equivalent to those of the referenced large-scale clinical trials, suggesting that medication histories are useful for drug-induced risk assessment.</p>