Introduction/objectivesThis randomized controlled intervention study investigated the effect of flaxseed poultice compress application on pain and hand functions in patients with primary interphalangeal hand osteoarthritis (OA).MethodThe study sample consisted of 82 patients who met the inclusion criteria in the Rheumatology Outpatient Clinic at a University Hospital between January 15, 2017, and May 15, 2018. Patients included in the sample groups were selected randomly. Three sample groups were formed: intervention group I (flaxseed poultice compress) (n=33), intervention group II (hot compress) (n=29), and control group (n=20). The interventions were applied once a day for 7days in a row. These patients also continued their routine pharmacological treatment. descriptive characteristics identification form, visual analog scale (VAS), Australian-Canadian (AUSCAN) Osteoarthritis (OA) Hand Index, and side effect evaluation form were used as data collection tools.ResultsThe means of VAS scores of patients in the intervention group I were 6.030.25 on day 0, 2.2 +/- 0.30 on day 8, and 3.39 +/- 0.32 on day 15. The means of AUSCAN total scores of patients in the intervention group I were 40.84 +/- 1.76 on day 0, 14.03 +/- 1.66 on day 8, and 15.78 +/- 1.66 on day 15. The present study showed that pain significantly decreased and the hand function efficiency increased in patients treated with flaxseed poultice compress compared with the hot compress and control groups.Conclusions In addition to pharmacological treatment, flaxseed poultice compress intervention is recommended to be used as a nursing intervention for reducing pain and increasing hand functions for patients with hand OA in cooperation with the physicians and other health professionals.