Caution when using Arnica products
The bottom line
Arnica is fairly safe when used for short periods or in very diluted forms. However, eating the plant, the topical creams or ointments, or the plant extracts or oils, can result in serious poisoning. People who are pregnant or who are feeding their infant via lactation, as well as people taking anticoagulants, should not use Arnica.
Prevention Tips
Do not take Arnica if you are pregnant or feeding your infant via lactation.
Ask your pharmacist to check for drug interactions before you start using Arnica.
Let your children know that no part of the plant should be eaten.
Only use topical Arnica creams and ointments for short periods of time.
Store all Arnica products out of the reach and sight of children.
This Really Happened
Case 1. A 9-day-old infant boy who was being fed via lactation was brought to an ER 48 hours after his mother began drinking Arnica tea. He had jaundice and severe hemolysis (destruction of red blood cells). He was treated with 2 blood transfusions and recovered fully (from Miller, 2009).
Case 2. A 24-year-old woman drank a cup of tea prepared from Arnica flowers and developed heart palpitations, a fast heartbeat, and diarrhea 2 hours later. She was given intravenous fluids in a hospital and recovered fully (from Canders, 2014).
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What is Arnica
Arnica is a flowering herb in the sunflower family that closely resembles daisies. It grows in Siberia, central Europe, Canada, and northern US. The yellow/orange flowers have been used as far back as the 1500s to treat a wide range of conditions, including bruises, sprains, muscle aches, wounds, joint pain, swelling, and burns. It is most commonly available in topical creams and ointments that can be applied to the skin. Arnica is also available as very diluted homeopathic products that can be taken by mouth.
Does Arnica work?
No one really knows how Arnica works. It is thought that the chemicals that are medically useful are located in the flower heads and in the lower stems of the plant. There is some evidence showing that these chemicals might help with inflammation and pain, but they can also limit a person's ability to form blood clots, increasing their risk for serious bleeding.
Arnica-based topical creams: are they safe?
Arnica is thought to have limited toxicity when applied to unbroken skin for short periods of time. Arnica should not be used on broken skin and can cause allergic skin reactions as well as cross reactions in people allergic to members of the Asteraceae or Compositae families of plants (such as chamomile, chrysanthemum, dandelion, marigold, and sunflower).
Arnica in food: can you ingest it?
Arnica is usually safe when taken by mouth in very dilute forms. The US Food and Drug Administration has classified Arnica to be “generally recognized as safe.” However, the Canadian government was sufficiently concerned about the safety of Arnica that it banned its use as an ingredient in food.
Potential harmful effects
Large amounts of undiluted Arnica can cause irritation or damage to the skin, mouth, throat, and stomach, as well as vomiting, diarrhea, rashes, shortness of breath, fast heartbeat, high blood pressure, damage to the heart and other organs, and increased bleeding. Arnica is not safe to use if you are pregnant or feeding your infant via lactation. Drinking Arnica teas or tinctures can result in miscarriage, and Arnica tea was the likely cause of hemolytic anemia in an infant fed via lactation when the mother drank the tea.
Because of its ability to prevent clots from forming, Arnica should not be taken with other medications or herbal products that can thin the blood, like aspirin, clopidogrel, warfarin, enoxaparin, apixaban, dabigatran, rivaroxaban, ginger, garlic, or ginseng, to name a few.
If you are taking Arnica and you have an upcoming surgery, let your surgeon know and stop taking the Arnica at least 2 weeks before the procedure. If you aren't sure if it is safe to take Arnica with your daily medications, ask your pharmacist to check for interactions.
Have more questions?
If you suspect someone has been exposed to Arnica and is having a problem, use the webPOISONCONTROL® online tool to get help, or call your poison center at 1-800-222-1222. Whether online or by phone, expert guidance is always free, confidential, and available 24 hours a day.
For More Info
References
Arnica. Natural Medicines Comprehensive Database. Therapeutic Research Center. 2014. Accessed August 4, 2019.
Miller AD, Ly BT, Clark RF. Neonatal hemolysis associated with nursing mother ingestion of Arnica tea [abstract]. Clin Toxicol. 2009;47(7):726.
Topliff A, Grande G. Significant toxicity after the ingestion of Arnica [abstract]. Clin Toxicol. 2000;38(5):518.
