I am glad to see you have stuck in it this far about learning the safety and uses of arnica. Today we are looking at the safety recommendations around using arnica internally at a full strength, non-homeopathically. This is very important to read if you are going to be using arnica internally at all because it is a POISON!
Traditionally, arnica was used in fluid extract form, a tincture at a 1:10 extract. When used as an tea/infusion there are fine fibers that can cause irritation of the throat, nausea, and vomiting. Extract dosage for internal use is drop dosed, up to 2ml, usually ¼ to 10 drops. When first swallowed, it causes burning in the throat, nausea, vomiting, gastric pains and loss of appetite. A safe internal dosage of 15-30 drops of tincture in four ounces of water, taking a teaspoon of this, every hour, is a reasonable dose.
The first signs of poison are seen in the gastric system and nervous system. In addition to the above gastric concerns, large doses arnica cause spasmodic contractions of the limbs, difficulty breathing, intense headaches, violent nervous responses, inflammation of the digestive tract, coma, and then death. Poisonous doses cause unconsciousness, paralysis, and coma. Death is seen at two ounces of a 1:10 tincture. With most arnica tinctures available today being a 1:5 extract, this would suggest that death would be assured at 30 ml, or one ounce of tincture.
Long term effects of arnica are not known and most adverse reactions, other than poisoning, are mild and short term. Sesqueterpene lactones are generally cardiotoxic and can also alter calcium levels, changing the pulse rate and altering the ability of nerves to send signals. Arnica has also been studied in relation to blood platelets. Their response to damage is reduced in response to arnica, lowering the body’s ability to heal. As such, it should not be used with anti-platelet or anti-coagulant drugs.
Other than these toxic effects, there are many challenges with identifying arnica. There are a wide variety of arnica species and we are not clear in which species were used by traditional herbalists. Today, research is done on a variety of different arnica species and I have tried my best to only include research here on the Arnica montana species, which is most commonly available arnica species on the market.
With arnica being in the aster family, it is common for arnica to cause allergic reactions in individuals. In San Francisco, a study looking at adverse events of herbs found arnica to be the 10th most reported herb for adverse events between 1966 and 2000. This may or may not have been internal usage but is reported to be due to its plant family ties with echinacea, another aster, also being in the top 10. Another study of arnica found that only 5 out of 443 individuals tested had an allergic reaction to arnica so the cause for worry may or may not be as high as suspected.
Even with these concerns, arnica is a flavoring ingredient in a variety of alcoholic beverages, non-alcoholic beverages, frozen dairy desserts, candy, baked goods, gelatins, and puddings. In these instances it is considered possibly safe. The FDA lists arnica as a GRAS herb, generally recognized as safe, for use as an alcoholic beverage flavoring agent. It is also used in hair tonics, antidandruff products, perfumes, and cosmetics, all at a low dose approved by the FDA.
Please continue to follow us for more information on the more obscure uses of arnica next week. I hope you will also check out our website and look at our arnica cream that is a 5% cream with calendula and St. John’s wort. We have a number of high quality herbal products as well as excellent resources for learning more about herbs through our new FREE Online Herbal Studies Program.