Background <p>High opioid use among individuals with chronic non-cancer pain (CNCP) raises concerns about safe pain management, leading some patients to seek complementary and alternative medicine (CAM). However, treatment-seeking patterns, including how CAM and conventional care are combined, remain unclear among those receiving long-term opioid treatment. The aim was to investigate health-seeking behaviours among individuals with CNCP receiving long-term opioid treatment.</p> Methods <p>Repeated cross-sectional data from the Danish Health and Morbidity Surveys (2000–2021) were linked to national administrative registers at the individual level. Descriptive statistics and multiple linear and logistic regression models were applied to analyze CAM use, general practitioner (GP) consultations, physiotherapy, and chiropractic care within the last 12 months in relation to CNCP and long-term opioid use.</p> Results <p>Trends remained largely unchanged from 2000 to 2021, with only minor fluctuations. GP consultations increased with long-term opioid use and were further elevated among individuals with CNCP who also used CAM. Among individuals with CNCP, combined long-term opioid and CAM use was associated with an average of 20.1 additional GP visits (95% CI: 17.5–22.7) compared with individuals without CNCP and no CAM use. Physiotherapy and chiropractic visits were more strongly associated with CAM use than with long-term opioid use. For instance, CNCP individuals using CAM without long-term opioid use had 5.8 times higher odds (95% CI: 4.6–7.4) of at least one chiropractor visit compared with those without CNCP and no CAM use.</p> Conclusion <p>These findings highlight distinct health care‑seeking patterns and indicate a substantial health care burden among CNCP individuals receiving long‑term opioid treatment.</p>