Arnica is an herb that grows mainly in Siberia and central Europe, as well as temperate climates in North America. The flowers of the plant are used in medicine. Arnica is most commonly used for pain caused by Osteoarthrtis, Sore throat, surgery, and other conditions. Arnica is also used for bleeding, bruising, swelling after surgery, and other conditions, but there is no good scientific evidence to support these uses. Arnica can also be unsafe when taken by mouth.
In foods, arnica is a flavor ingredient in beverages, frozen dairy desserts, candy, baked goods, gelatins, and puddings. In manufacturing, arnica is used in hair tonics and anti-dandruff preparations. The oil is used in perfumes and cosmetics.
Possibly Effective for
Early research shows that using an arnica gel product (A. Vogel Arnica Gel, Bioforce AG) twice daily for 3 weeks reduces pain and stiffness and improves function in people with osteoarthritis in the hand or knee. Other research shows that using the same gel works as well as the painkiller ibuprofen in reducing pain and improving function in the hands.
Possibly Ineffective for
Reducing pain, swelling, and complications of wisdom tooth removal. In most research, taking arnica by mouth does not seem to reduce pain, swelling, or complications after wisdom tooth removal. One early study suggests that taking six doses of homeopathic arnica 30C might reduce pain, but not bleeding.
Insufficient Evidence for
Bleeding. Early research suggests that placing 5 drops of a homeopathic arnica preparation under the tongue three times per day might reduce blood loss following surgery for breast cancer. But problems with the design of this study limit the reliability of these results.
Bruises. Most research shows that taking homeopathic arnica by mouth or applying arnica to the skin does not reduce bruising after surgery. But several conflicting studies shows benefit.
Vision problems due to diabetes. Early research shows that taking homeopathic arnica by mouth for 6 months reduces vision problems in people with vision loss due to diabetes.
Arnica is POSSIBLY SAFE when taken by mouth in the amounts commonly found in food or when applied to unbroken skin short-term. The Canadian government, however, is concerned enough about the safety of arnica to prohibit its use as a food ingredient.
Amounts that are larger than the amount found in food are LIKELY UNSAFE when taken by mouth. In fact, arnica is considered poisonous and has caused death. When taken by mouth it can also cause irritation of the mouth and throat, stomach pain, vomiting, diarrhea, skin rashes, shortness of breath, a fast heartbeat, an increase in blood pressure, heart damage, organ failure, increased bleeding, coma, and death.
Arnica is often listed as an ingredient in homeopathic products; however, these products are usually so dilute that they contain little or no detectable amount of arnica.