Objective: To study the efficacy of Immortelle extracts, Arnica, Longan seed, Plai (I-ALP) analgesic gel in acute and subacute musculoskeletal pain.

Materials and Methods: The present study was conducted at the Rehabilitation Center of a tertiary referral hospital. A novel herbal gel consisting of Plai, Longan seed, Arnica, and Immortelle extracts was developed. One hundred four patients with acute and subacute musculoskeletal pain, with a numerical rating scale (NRS) of 3 or less, were randomized to two equal groups with the treatment group and control group, both having 60 patients each. The treatment group received I-ALP analgesic gel with rehabilitation and a physical therapy program while the control group received placebo gel with rehabilitation and a physical therapy program. Both groups were instructed to apply analgesic gel in the painful area

twice a day, in combination with the rehabilitation and physical therapy program, three times a week for two weeks. Both groups were assessed for NRS score, active range of motion, and quality of life in pretest, during the test at one week, and post-test at two weeks.

Results: Ninety-five patients completed the experimental study, with 50 in the intervention group and 45 in the placebo group. Four herbal extracts, including Plai extract 14%, Longan seed extract 8%, Arnica extract 5%, and Immortelle extract 4%, were developed as the I-ALP analgesic gel. The present study found that the treatment group had significant reduction in pain response rate (p<0.05). Within one week, 26% of the treatment group had a reduction of NRS scores of 50%. At post two weeks, 88% of the treatment group had reduction of NRS scores of 50%. The number of patients in the treatment group who had reduced pain response rate was up to 3.67 times greater than in the control group (95% confidence

interval 1.33 to 11.28). There was no significant difference in quality-of-life scores between the two groups.

Conclusion: The I-ALP analgesic gel effectively reduces pain in patients with musculoskeletal pain in acute and subacute phases.