Arnica can cause death, stomach pain, vomiting and diarrhea when eaten in larger amounts than is normally found in food. Other side effects from excessive doses include irritation of the mouth and throat, skin rashes, a quickened heartbeat and shortness of breath, according to WebMD.Continue Reading
Possible side effects of too much arnica include organ failure, heart damage, increased blood pressure, coma and increased bleeding. Applying arnica to broken skin may cause too much to be absorbed. Arnica is possibly safe when applied to unbroken skin short-term, or when it is taken orally in the amounts commonly found in food. Although some homeopathic products list arnica as an ingredient, the products are often diluted heavily so very little arnica is actually present, notes WebMD.
Those with conditions related to the intestines, such as ulcers, Crohn's disease or irritable bowel syndrome, should not take arnica. People with a fast heart rate should avoid arnica as it increases the heart rate. Arnica increases blood pressure, so people with high blood pressure should not take it, according to WebMD.
People who are allergic to the Asteraceae/Compositae family of plants may be allergic to arnica. Pregnant or nursing women should not use arnica. Arnica should not be taken within 2 weeks of surgery, as it may cause excessive bleeding, states WebMD.Learn more about Side Effects