Question & Answer

The Evidence

• Arnica is a plant from the daisy family that some people use for treating bruising and injury.
• There are two ways to use arnica; one is in creams, gels and ointments, and the other is in dilution in highly diluted or homoeopathic doses, which are swallowed.
• Arnica contains anti-inflammatory substances, which might explain an effect from gels or ointments, but this cannot explain how extremely low homoeopathic doses would work.
• We found seven systematic reviews about arnica.
• Two of these looked at arnica creams, gels or ointments (topical arnica):
  • The first of these found that arnica ointment in high concentrations might help pain, swelling and bruising, but this was uncertain. Lower concentrations seemed to have no effect.
  • The second review included only one study of people with osteoarthritis, and found that arnica gel was slightly better than ibuprofen gel in improving pain and physical movement, but there were slightly more side effects with arnica.
• Three studies looked at homoeopathic doses of arnica taken by mouth:
  • The first reported that some studies showed that arnica appeared to be beneficial (mainly to help healing after operations) and some did not. However, the studies were not good enough to be sure of this finding.
  • The second review included only one study in people who had three types of knee surgery. There was reduced swelling after cruciate repair surgery but not after knee replacement and keyhole surgery – but there were very few people in the group having cruciate repair. We would need larger trials to be certain that arnica can help in cruciate surgery.
  • The third found small benefits from arnica in patients who had operations or teeth removed, but this finding could have happened by chance and cannot be relied on.
• Two studies looked at both topical and homoeopathic arnica:
  • One reported that some studies found benefits from arnica after operations, and some did not. However, it was not possible to say for definite whether arnica does or does not work.
  • The other looked at patients after cosmetic nose surgery and found that eyelid swelling was better in those taking arnica two days post-surgery, but after one week, there was no difference compared with people who did not take it. Patients taking arnica had less bruising than those who did not take it at both time points. However, as this review combined results from two different types of arnica and isn’t of high quality so it is difficult to be sure of the findings.
• Overall, the studies included in these reviews included small numbers of people, and the treatments used varied. This makes it difficult to be sure of the results.

Guidelines and recommendations

• The HSE says that arnica is used by some women to help heal episiotomies (surgical cuts given during labour) after giving birth. However, they also say that the scientific evidence on arnica is not definite.