What Is Arnica?

Arnica is a homeopathic herb used to treat aches, pains, and bruises. Arnica plants have long, downy leaves, and the flowers are daisy-like. It comes from the subalpine regions of western North America and can also be found in the Arctic.

An herb in the sunflower family (Asteraceae), arnica has been thought to contain anti-inflammatory compounds that relieve muscle and joint pain. Arnica can be applied topically to the skin as a gel. Oral forms are also available as teas, tinctures, and tablets.

The anti-inflammatory ingredient in arnica is called helenalin. This compound is toxic when consumed. It can also irritate the skin if it is not diluted.

This article discusses the potential uses of arnica and the risk factors and side effects of taking arnica.

Purported Uses of Arnica

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian nutritionist, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Arnica is commonly used in complementary and alternative medicine. It has been researched for use in:

• Bruising
• Pain
• Myalgia, or muscle soreness
• Arthralgia, or aching joints

The plant can be toxic. Because of this, it is most often used in a homeopathic form. Homeopathic products contain very small amounts of the active ingredient.

Research on the potential health benefits of arnica is limited. There is NOT enough evidence to support its use for any of these conditions due to a lack of human research. More research is needed. Very few well-designed, placebo-controlled, peer-reviewed human studies have been published.

Osteoarthritis

Osteoarthritis is often referred to as "wear-and-tear" arthritis. In this condition, the cartilage that protects the joints wears down over time. It is often treated with nonsteroidal anti-inflammatory drugs (NSAIDs) or other pain relievers.

In one review of several studies, Australian researchers looked at seven trials of topical herbal remedies for osteoarthritis. Arnica gel appeared to work nearly as well as Advil (ibuprofen). Benefits included reduced and improved joint function in people with hand osteoarthritis.

However, in one of the seven trials, 13% of those who used arnica gel had side effects. This is compared to 8% of Advil users. Some even reported an increase in joint stiffness and pain.

More research is needed. Discuss with your healthcare provider about taking arnica for your osteoarthritis before starting this supplement.

What Are the Side Effects of Arnica?

Arnica is known to cause side effects. This is true even when used in very diluted topical ointments or creams. More serious side effects can occur with oral forms.

Topical Use

In less-diluted formulas, arnica may cause a mild allergic reaction. This happens most often in people allergic to plants of the Asteraceae family. These plants include:

• Ragweed
• Marigolds
• Chrysanthemums
• Daisies

Arnica can also trigger increases in blood pressure and heart rate. This is more likely if used in excess or on broken skin. More of the active ingredient can be absorbed through broken skin. On broken skin, arnica may also cause stinging.

Oral Use

Most homeopathic arnica remedies are very diluted. These are generally considered safe. Some forms, though, may contain detectable amounts of helenalin. These forms have health risks.

When taken by mouth, helenalin can cause:

• Mouth and throat irritation
• Stomach pain
• Diarrhea
• Vomiting
• Shortness of breath
• Easy bruising and bleeding
• Rapid heartbeat
• High blood pressure

Precautions

Pregnant or lactating individuals and children should not take arnica in any form. Individuals allergic to ragweed and related plants (e.g., chrysanthemums, marigolds, daisies) who take arnica may have an allergic reaction.

It is also recommended to stop taking arnica two weeks before surgery, as it may cause extra bleeding before and after surgery.

Dosage: How Much Arnica Should I Take?

There is not enough scientific evidence to determine a standard or appropriate dose of arnica. More research is needed on dosages for specific health needs and populations.

What Happens If I Take Too Much Arnica?

As a rule of thumb, never take more than the manufacturer's recommended dosage. If you experience side effects of any kind, stop taking arnica and call your healthcare provider.

Interactions

Avoid arnica if you are taking blood-thinning medication. The combination could increase your risk of bleeding and bruising.

Arnica may interact negatively with these medications:

• Jantoven (warfarin)
• Plavix (clopidogrel)
• Heparin
• NSAIDs, like ibuprofen and Naprosyn (naproxen)

Supplements that can slow blood clotting should also be avoided, such as garlic, ginger, ginkgo, and Panax ginseng.

It is essential to carefully read a supplement's ingredient list and nutrition facts panel to know which ingredients and how much of each ingredient is included. Please review this supplement label with your healthcare provider to discuss potential interactions with foods, other supplements, and medications.

How to Store Arnica

Store arnica according to the manufacturer's directions. Discard as indicated on the packaging.

Sources of Arnica & What to Look For

Arnica is often sold as an over-the-counter (OTC) product in topical and oral forms. Arnica is also sold as a homeopathic oral pellet.

Homeopathic remedies are highly diluted and often thought of as safe. However, in large doses arnica can be poisonous. Oral use of arnica is not generally recommended unless it is very diluted and under the care of a healthcare provider.

There is no scientific evidence to suggest which form is best. Additionally, there are safety concerns when taking this or any supplement. Remember that it is illegal for any company to market a dietary supplement product as a treatment or cure for a specific disease.

Summary

Arnica is an herb believed to help relieve pain associated with arthritis and muscle soreness. It is available in topical and oral forms.

When it is undiluted, arnica may cause side effects like nausea, rapid heart rate, and bruising or bleeding. It may also interact with blood-thinning drugs. Always speak with your healthcare provider before taking arnica or any other supplement.