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Arnica

Arnica is a plant whose flowers are used to make medicine. Arnica is applied to the skin for pain and swelling associated with bruises, sprains and arthritis. Arnica is also applied to the skin for insect bites, muscle and joint pain, chapped lips and acne. Arnica is taken orally for inflammation of the mouth and throat, insect bites, painful and swollen veins on the surface of the skin, sore gums after the removal of wisdom teeth and to induce abortion. In food, arnica is used as a flavoring agent in drinks, frozen dairy desserts, sweets, baked goods and puddings. Arnica is also used in the manufacture of hair tonics and anti-dandruff products. The oil is used in the manufacture of perfumes and cosmetics.

How does arnica work?

The chemicals contained in arnica can reduce swelling, relieve pain and act as an antibiotic.

How effective is arnica?

Arnica may be ineffective when it comes to reducing pain, swelling and complications from wisdom teeth removal. There is not enough scientific data to make a statement about the effectiveness of arnica for bruising, pain, sprains, muscle pain, insect bites, sore throats, chapped lips and acne. Further scientific research is needed to evaluate the effectiveness of arnica for these conditions.

Are there any safety concerns?

Arnica may be safe when used in the amounts normally found in foods or when applied to intact skin for short periods of time. However, arnica is not approved as a food ingredient in Canada due to safety concerns. Amounts higher than those found in food are probably not safe for oral ingestion. Arnica is considered toxic and deaths have occurred. When taken orally, arnica can cause irritation of the mouth and throat, stomach pain, vomiting, diarrhea, skin rashes, shortness of breath, rapid heartbeat, an increase in blood pressure, heart damage and coma as side effects. Arnica should not be applied to damaged or fragile skin as too much of the active ingredients may be absorbed.

Precautions and warnings

  • Pregnancy and breastfeeding: Pregnant or breastfeeding women should not take arnica orally or apply it to the skin, as arnica is not considered safe and harmless during pregnancy and breastfeeding.
  • Allergies to broomweed and related plants: Arnica can cause allergic reactions in people who are sensitive to plants in the Asteraceae/Compositae family. Members of this plant family include broomsedge, chrysanthemums, marigolds and daisies. If you suffer from allergies, you should consult your doctor before using arnica on your skin and should not take arnica orally.
  • Digestive problems: Arnica can irritate the digestive tract. For this reason, you should not take arnica orally if you suffer from irritable bowel syndrome, stomach ulcers, Crohn's disease or other problems in the stomach and intestines.
  • Operations: Arnica can cause bleeding during and after surgery. For this reason, you should stop using arnica at least two weeks before an operation.

Interactions with medications

Care should be taken when combining arnica with the following medications:

Medications that slow down blood clotting

Arnica can slow down blood clotting. Taking arnica in combination with medications that also slow down blood clotting could increase the risk of bleeding and the tendency to bruise.

Dosage

The appropriate dosage of arnica depends on various factors such as age, state of health and others. Currently, there is not enough scientific information to determine an appropriate dosage range for arnica. For this reason, you should follow the dosage instructions on the label and/or consult a doctor or pharmacist before using arnica products.

References

  1. Adkison JD, Bauer DW, Chang T. The effect of topical arnica on muscle pain. Ann Pharmacother 2010;44:1579-84.
  2. Electronic Code of Federal Regulations. Title 21 Part 182 -- Substances Generally Recognized As Safe. Available at: http://ecfr.gpoaccess.gov/cgi/t/text/text-idx?c=ecfr&sid= 786bafc6f6343634fbf79fcdca7061e1&rgn=div5&view= text&node=21:3.0.1.1.13&idno=21
  3. Kaziro GS. Metronidazole (Flagyl) and Arnica Montana in the prevention of post-surgical complications, a comparative placebo controlled clinical trial. Br J Oral Maxillofac Surg 1984;22:42-9.
  4. Lyss G, Schmidt TJ, Merfort I, Pahl HL, et al. Helenalin, an anti-inflammatory sesquiterpene lactone from Arnica, selectively inhibits transcription factor NF-kappa B. Biol Chem 1997;378:951-61.
  5. Schroder H, Losche W, Strobach H, et al. Helenalin and 11 alpha, 13-dihydrohelenalin, two constituents from Arnica montana L., inhibit human platelet function via thiol-dependent pathways. Thromb Res 1990;57:839-45.