The effect of topical arnica on muscle pain

The herb Arnica montana, in topical formulations, has been reputed to decrease bruising and muscle pain. This claim has been inadequately and incompletely addressed.

To determine whether topical A. montana cream could decrease subjective leg pain following calf raises. Secondary outcomes were effects on ankle range of motion and muscle tenderness.

A randomized, double-blind, placebo-controlled trial was conducted in 53 subjects. Active range of motion was measured in both ankles, and then a series of calf-raises were completed according to a standardized protocol. Each participant received 2 tubes of cream, 1 with active arnica and 1 with placebo. The creams were applied to the lower legs immediately after the exercise, and again at 24 and 48 hours postexercise according to the "RIGHT" or "LEFT" labels. At 48 hours postexercise, subjects had their ankle range of motion and muscle tenderness measured. Subjects used the analog scale to rate pain in each leg at baseline, 24 hours, 48 hours, and 72 hours.

No significant differences in pain scores were seen before exercise (arnica: 0.07 vs placebo: 0.09, p = 0.32). Pain scores on legs treated with arnica were higher than scores on those receiving placebo 24 hours after exercise (3.04 vs 2.36, respectively; p < 0.005). Pain scores on day 3 (arnica: 3.44 vs placebo: 3.20, p = 0.66) and day 4 (arnica: 2.36 vs placebo: 2.31, p = 0.62) were not significantly different. There was no difference in muscle tenderness (arnica: 1.05 vs placebo: 1.05, p = 1.0). Ankle range of motion did not differ significantly on either day 1 (arnica: 64.70 degrees vs placebo: 66.15, p = 0.352 or day 3 (arnica: 63.32 degrees vs placebo: 65.94, p = 0.058).

Rather than decreasing leg pain, arnica was found to increase leg pain 24 hours after eccentric calf exercises. This effect did not extend to the 48-hour measurement.