Topical arnica increases muscle pain

Oops. Topically applied Arnica montana is reputed to decrease bruising and muscle pain.

But in this study, researchers at the Memorial Family Medicine Residency Program, in Sugar Land, Texas, found an opposite effect.

First, the details.

  • In 53 people, active range of motion was measured in both ankles, and then a series of calf-raises were completed.
  • The participants received 2 tubes of cream: 1 with active arnica and 1 with placebo.
  • The creams were applied to the lower legs immediately after exercise, and again at 24 and 48 hours later according to the “RIGHT” or “LEFT” labels.
  • At 48 hours, ankle range of motion and muscle tenderness were measured.
  • Participants rated pain before the study and at 24, 48, and 72 hours after the study.
  • Neither the patients nor researchers knew the treatment given — double blind.

And, the results.

  • There were no significant differences in pain scores before exercise.
  • Pain scores on legs treated with arnica were significantly higher than scores on those receiving placebo 24 hours after exercise.
  • Pain scores on days 3 and 4 didn’t differ.
  • There was no difference in muscle tenderness or on ankle range of motion on day 1 or day 3.

The bottom line?

Accordingly, the authors concluded, “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.”

The abstract failed to disclose the concentration of arnica applied to the skin, although there’s no indication that the cream used was homeopathic.

With regard evidence supporting homeopathic arnica to reduce muscle pain, several years ago, Prof. Ernst reviewed the effectiveness of homeopathic arnica and concluded, “The claim that homeopathic arnica is efficacious beyond a placebo effect is not supported by rigorous clinical trials.”

For higher concentrations, a PubMed search revealed only 1 other study in Marathon runners where arnica was compared to placebo.

Researchers from Norway reported that muscle soreness immediately following a marathon run was significantly lower in the arnica group than in the placebo group. However, cell damage measured by enzymes was similar in the arnica and the placebo group.

In the absence of rigorous scientific research and strong support for arnica, before applying it to your skin, consider the findings of a recent review of the risk of contact allergy and herbal medicines. The researchers warned, ‘Sensitization seems to occur relatively frequent with… arnica.”

9/2/10 15:46 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.