371: Paracetamol demonstrates efficacy comparable to celecoxib in patients with chronic low back pain

Topic: Clinical Science
Subtopic: Pain category (ICD-11), Chronic primary musculoskeletal pain, Pharmacological treatments

Background and Aims: Pharmacological treatment is commonly used for patients with chronic low back pain (CLBP). However, despite its widespread use, the evidence supporting paracetamol as a treatment option for CLBP remains of low quality, leading to contradictory recommendations across guidelines. A nonrandomized observational study suggested that paracetamol has analgesic effects comparable to nonsteroidal anti-inflammatory drugs in patients with CLBP. Therefore, this randomized controlled study aimed to compare the analgesic effects of paracetamol and celecoxib in a non-inferiority trial. This non-inferiority trial tested the hypothesis that paracetamol is as effective as celecoxib for the treatment of CLBP within a pre-specified non-inferiority margin.

Methods: One hundred fifty-six patients with CLBP were considered eligible and randomly allocated to a group receiving paracetamol or celecoxib. The paracetamol group received 1,000 mg paracetamol tablets 3 times daily (3,000 mg per day) for 4 weeks, and the celecoxib group received 100 mg celecoxib tablets 2 times daily (200 mg per day) for 4 weeks. Outcome measures were assessed at baseline and at weeks two and four after starting the medication. The pain intensity was measured using a numerical rating scale as the primary outcome. Secondary outcomes were pain-related psychological variables, quality of life, and adverse events.

Results: One hundred thirty-nine patients completed the study (paracetamol, 70; celecoxib, 69). The mean differences in the NRS changes between the two medication groups from baseline to weeks two and four did not significantly exceed the non-inferiority margin. The PDAS, HADS-Anxiety, and HADS-Depression values in the paracetamol group were significantly decreased compared with the celecoxib group at weeks two and four. The EQ-5D-3L value in the paracetamol group was significantly increased compared with the celecoxib group at week 4. Adverse effects were observed more frequently in the celecoxib group (6 of 69) compared to the paracetamol group (2 of 70).

Conclusions: The present randomized controlled clinical trial suggested that the mean difference in changes in NRS scores over four weeks between the two medication groups did not statistically exceed the specified non-inferiority margin, suggesting that paracetamol provides analgesic effects comparable to celecoxib for CLBP. Paracetamol demonstrated superior effects on pain-related psychological variables and quality of life compared to celecoxib. The mechanism of action is complex and involves both peripheral and central antinociceptive processes, as well as redox mechanisms. Recent studies highlight that paracetamol may reduce pain through neurochemical changes within the central nervous system.

References: Miki K, Ikemoto T, Hayashi K, Arai YC, Sekiguchi M, Shi K, Ushida T. Randomized open-label non-inferiority trial of acetaminophen or loxoprofen for patients with acute low back pain. J Orthop Sci. 2018; 23(3):483-487.
Hayashi K, Miki K, Kajiyama H, Ikemoto T, Yukioka M. Impact of Non-steroidal Anti-inflammatory Drug Administration for 12 Months on Renal Function. Front Pain Res (Lausanne). 2021; 2:644391.
Hayashi K, Miki K, Shiro Y, Tetsunaga T, Takasusuki T, Hosoi M, Yukioka M. Utilization of telemedicine in conjunction with wearable devices for patients with chronic musculoskeletal pain: a randomized controlled clinical trial. Sci Rep. 2025; 15(1):1396.

Presenting Author: Kazuhiro Hayashi
Submitting Author: Kazuhiro Hayashi

Senior Author: Kazuhiro Hayashi

IASP 2026 Global Year theme of Neuropathic Pain: No

• Kenji Miki: MD, PhD - Faculty of Health Science, Osaka Yukioka College of Health Science, Ibaraki, Japan.