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Arnica

Arnica is an herb that grows in Europe and the U.S. It’s often used as a skin treatment for bruises, aches, and pains.

Arnica Uses

Early studies of topical arnica gels and ointments for arthritis symptoms of the hand and knee -- like pain and swelling -- have been positive. So far, research is mixed on whether  arnica skin treatments can help ease muscle pain.

If eaten, the actual herb is toxic and can be fatal. However, some oral supplements contain highly diluted arnica. These are considered homeopathic treatments. These low-dose arnica tablets are safe to use and have been studied for muscle pain, diabetic eye damage, and swelling and pain after surgery. More research needs to be done to establish effectiveness for those problems. A study of children with cancer, however, found that homeopathic low-dose arnica may help reduce mouth ulcers related to chemotherapy.

Because of the risks of pure arnica, the FDA classifies it as an unsafe herb.  Doctors who practice complementary medicine generally advise against using arnica in any form other than in a highly diluted homeopathic form.

Arnica Dose & Instructions for Use

Since arnica is an unproven treatment, there is no clear advice on how to use it. Given its risks, talk to a doctor or pharmacist before taking arnica.

Arnica Food Sources

There are no natural food sources of arnica besides the plant itself. Arnica is used as a flavoring in some food products.

Arnica Supplement Information

Arnica can come in tablets, tinctures, ointments, gels, and mouth rinses. Like any supplement, keep arnica in a cool, dry place, away from humidity and direct sunlight.

Arnica Warnings

  • Side effects. Pure arnica herb is poisonous. Homeopathic doses are generally considered safe to use. Arnica creams or gels can cause burning and skin irritation. Arnica can trigger allergic reactions in some people, including those who have allergies to plants like ragweed, daisies, marigolds, or chrysanthemums. 
  • Risks. Always talk to a doctor before using arnica. When swallowed, pure arnica can cause rapid heartbeat, gastrointestinal problems, kidney and liver damage, coma, and death. Don’t use undiluted arnica topically on broken or sensitive skin.
  • Interactions. If you take any medicines regularly, discuss them with your doctor before you start using arnica supplements. They could interact with drugs like painkillers, steroids, blood pressure drugs, blood thinners, and herbs like ginkgo biloba, garlic, and saw palmetto.

Given the lack of evidence about its safety, arnica is not recommended for children and is considered unsafe for women who are pregnant or breastfeeding.

WebMD Medical Reference

Reviewed by Melinda Ratini, DO, MS on August 18, 2014

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