Objective: To identify potentially inappropriate medications (PIMs), to compare drug changes between geriatric and other medical wards, and to investigate the clinical impact of PIMs in acutely hospitalized older adults.Setting and subjects: Retrospective study of 232 home-dwelling, multimorbid older adults (aged ≥75 years) acutely admitted to Vestfold Hospital Trust, Norway.Main outcome measures. PIMs were identified by Norwegian general practice (NORGEP) criteria and Beers’ 2012 criteria. Clinical correlates were laboratory measures, functional and mental status, physical frailty, and length of stay.Results: Mean (SD) age was 86 (5.7) years, and length of stay was 6.5 (4.8) days. During the stay, the mean number of drugs used regularly changed from 7.8 (3.6) to 7.9 (3.6) (p = 0.22), and drugs used pro re nata (prn) changed from 1.4 (1.6) to 2.0 (1.7) (p < 0.001). The prevalence of any PIM changed from 39.2% to 37.9% (p = 0.076), while anticholinergics and benzodiazepines were reduced significantly (p ≤ 0.02). The geriatric ward reduced drug dosages (p < 0.001) and discontinued PIMs (p < 0.001) significantly more often than other medical wards. No relations between number of PIMS and clinical outcomes were identified, but the concomitant use of ≥3 psychotropic/opioid drugs was associated with reduced hand-grip strength (p ≤ 0.012).Conclusion: Hospitalization did not change polypharmacy or PIMs. Drug treatment was more appropriate on the geriatric than other medical wards. No clinical impact of PIMs was observed, but prescribers should be vigilant about concomitant prescription of ≥3 psychotropics/opioids.KEY POINTSAcute hospitalization of older patients with multimorbidity did not increase polypharmacy or potentially inappropriate medications.Prescription of anticholinergics and benzodiazepines was significantly reduced.The geriatric ward reduced drug dosages and discontinued potentially inappropriate medications more frequently than the other medical wards.