Side Effects of Arnica

Marye Audet
arnica montana

There are really very few side effects of arnica when it is used properly. In fact, when used externally, or in homeopathic doses for the recommended period of time, arnica is generally without side effects at all.

What is Arnica?

Arnica is a flowering plant which is found in Europe, although it has been adapted to other parts of the world. It is a member of the Sunflower family. The plant forms deep roots and a single stem rises from them. The leaves are soft and leathery and arranged in the shape of a rosette. When arnica blooms, the flowers are large with orange or yellow petals. The roots form rhizomes which are dark brown and cylindrical, with brittle rootlets.

Arnica is also known as:

  • Arnica Montana
  • Leopard's Bane
  • Wolf's Bane
  • Mountain Tobacco
  • Mountain Arnica
  • Mountain Snuff
  • Wolfbane

What is Arnica Used For?

Throughout the centuries, arnica has been used for a wide variety of maladies:

  • Reduce swelling
  • Pain reduction
  • Slow down bleeding
  • Reduce bruising
  • Insect bites
  • Skin Irritations
  • Promotes faster recovery after an operation
  • Helps muscles function effectively during labor
  • Motion Sickness

What are the Side Effects of Arnica?

While arnica is considered to be safe there are some cautions to abide by when using this herb.

Topical Use

When you use a topical preparation of arnica constantly for more than three weeks, it can lead to uncomfortable skin irritations. If you must use it for a length of time, stop using it for a week, and then begin again in a two weeks on and one week off cycle. This will keep you from having any possibility of skin irritation.

Arnica should not be used on an open wound or near the eyes or mouth.

Homeopathic Dose

If you are using a homeopathic dose of arnica, you should still abide by the two weeks on and one week off rule, unless your healthcare practitioner tells you differently. If a higher than recommended dose of arnica is given, the following side effects could occur:

  • Stomach discomfort
  • Nausea
  • Vomiting
  • Liver damage
  • Kidney damage
  • Organ Failure
  • Irregular heartbeat
  • High blood pressure
  • Rapid heart beat
  • Heart failure
  • Irritation of the throat
  • Mouth ulcers
  • Lesions in the mouth
  • Eczema
  • Decreased coagulation in the blood
  • Shortness of breath
  • Allergic dermatitis
  • Scarring from allergic dermatitis
  • Muscle paralysis
  • Diarrhea
  • Redness of the skin
  • Death
  • Stomach irritation
  • Irritation of the gastrointestinal tract

Drug Interactions

Arnica can increase the risk of bleeding, especially when used with anticoagulants or antiplatelet drugs like:

  • Warfarin/coumadin
  • Hepadrin
  • Plavix

In addition it could increase the possibility of bleeding if you are taking over the counter pain relievers such as:

  • Aspirin
  • Ibuprofen (Motrin, Advil)
  • Naproxen (Naprosyn, Aleve, Anaprox)

If you are on drugs to lower your blood pressure or treat diabetes, arnica can reduce the effectiveness of these drugs. Arnica can also reduce the effectiveness of corticosteroids. Discuss this with your health care provider.

If you are taking garlic or gingko biloba, arnica can also react with these herbs and increase the incidence of heavy bleeding in some cases.

Use of Arnica During Pregnancy and Breast Feeding

Homeopathic doses of arnica can be used to minimize discomfort during pregnancy. If you take it, always take the minimum homeopathic dose and stop immediately if you have any abnormal symptoms, especially cramping or bleeding.

Because the components of arnica pass through the placenta, and do get into the milk, it is best to stay away from arnica in any form during pregnancy and breastfeeding. Side effects of arnica can include spontaneous abortion as well as premature labor. Arnica can irritate the uterus and cause contractions long before a baby is ready to be born.

There are no known studies about the side effects of arnica on young children so it is best to stay away from it when nursing and talk to you naturopath before giving it to your child.

Homeopathic Doses of Arnica

While arnica does have side effects it is very, very rare for homeopathic remedies to have side effects because of how they are prepared. In normal situations it is safe to give arnica in the dose prescribed by the manufacturer. As with any medication, if you are in doubt check with your health care provider.

Side Effects of Arnica