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A Complete Overview of Arnica: Its History, Composition, Uses, and Side Effects

Published on August 22, 2023

By Lisa Stockwell

Lisa Stockwell

Lisa Stockwell has worked as a copywriter, writer, author, and editor for 35 years, specializing in the field of healthcare since 2009. She recognized the need for reliable health information while supporting friends through unique health challenges and refocused her career to bring clarity and compassion to healthcare communications. Lisa is a graduate of the University of California, Berkeley and a lifelong Northern Californian.
A Complete Overview of Arnica: Its History, Composition, Uses, and Side Effects
A Complete Overview of Arnica: Its History, Composition, Uses, and Side Effects

No one escapes life without occasional pain from bumps, bruises, and sprains. The challenge is how to treat that pain before it becomes chronic, a condition that burdens over 20 percent of the American population. REF#2707

Arnica, a perennial plant, has been used topically and in homeopathy for centuries as a supplement to support a healthy inflammation response and manage minor pain. If you’re looking for a plant-based option to manage occasional minor muscle soreness and joint discomfort, Arnica may provide the relief you seek.

What is Arnica?

Arnica is a plant in the Asteraceae (sunflower) family that grows in the mountain regions of Europe and North America. It has long, oval-shaped green leaves that grow level to the ground. From late spring through summer, Arnica produces bright yellow daisy-like flowers that extend up to two feet tall. Arnica has been called: mountain arnica, mountain tobacco, leopard’s bane, and wolf bane, and has been integrated into folk remedies in many cultures. 

Because of its growing popularity and wild harvesting, Arnica is becoming rare in its native habitat. To meet demand, it is being cultivated commercially, primarily in Europe and Chile.

There are approximately 30 species of Arnica, with Arnica montana believed to have the greatest health-promoting properties. Today, Arnica montana flowers are the most commonly used part of the plant for occasional minor pain support. The rhizomes are also used in some formulations.

Arnica may have been first mentioned in the 12th century, when legendary healer, Hildegard von Bingen, wrote about an herb that closely matches the plant in her book on health and healing, "Physica." In 1805, Samuel Hahnemann, the founder of homeopathy, published his findings on extremely diluted preparations of Arnica. The herb was approved for external use by the German Commission E in 1986. 

In traditional medicine, Arnica was commonly applied as a compress or salve for addressing bruises, swelling, and injuries. It was also used in foot baths to soothe sore feet.

Active Compounds in Arnica

Arnica contains a variety of active compounds that contribute to its potential health benefits. Some of the key constituents found in Arnica include:

  • Sesquiterpene lactones: These compounds are believed to be responsible for many of Arnica's health-promoting properties. Two important sesquiterpene lactones, helenalin, and dihydrohelenalin, have been shown to support normal inflammatory response. Helenalin is a toxic chemical, so Arnica should not be ingested except in an extremely diluted form. 
  • Flavonoids: Flavonoids are antioxidant compounds that are found in various plants. In Arnica, flavonoids like quercetin and luteolin contribute to its antioxidant and free-radical scavenging properties.
  • Carotenoids: Carotenoids are pigments found in plants that have antioxidant properties. 
  • Volatile oils: Thymol and ethers of thymol offer naturally occurring antioxidants and support healthy levels of inflammation.

The concentrations and specific effects of the above compounds can vary based on factors such as the plant's growth conditions, preparation methods, and the part of the plant that is used. More studies are needed to explain each constituent's mechanisms of action and potential health benefits. However, there has been significant research using placebo-controlled, randomized, double-blinded, and open multicenter trials that suggest the medicinal importance of this plant. 

Two Potential Health Benefits of Arnica

Arnica, when used topically, may support a normal inflammation response and provide minor pain management. Clinical studies suggest that creams, gels, oils, and roll-ons that contain Arnica may be effective in alleviating discomfort caused by bruises, bumps, and muscular strain.

No research has yet confirmed the use of homeopathic Arnica as an oral supplement for minor pain or occasional inflammation.

1. Arnica May Support Normal Inflammation Response 

Multiple studies have shown topical Arnica formulations support a normal inflammation response, relieving muscle soreness and joint discomfort caused by extreme exercise, bumps, and bruises.REF#2708 REF#2709 Topical treatment may also help relieve the swelling and redness caused by insect bites and stings.

As noted earlier, scientists believe that the sesquiterpene lactone, helenalin, acts as a bioactive compound, mediating your body's response to injuries. When you get injured, your body triggers an inflammatory response, leading to swelling and pain. Helenalin engages with the signaling molecules responsible for this inflammation. It operates as a regulator, maintaining a protective inflammatory response but preventing that response from becoming excessive and causing abnormal swelling and pain.

2. Arnica May Support Minor Pain Management

Arnica has been shown in clinical studies to be an effective and safe analgesic that may provide occasional relief from minor aches and pain. In an open multicenter trial, 79 adults with mild knee osteoarthritis were given Arnica twice a day for three or six weeks. Both the three-week and six-week groups showed a significant reduction in minor pain, stiffness, and lack of function. In a randomized, double-blind study of 204 patients with hand osteoarthritis, one group was given Arnica gel and the other an ibuprofen gel three times a day for three weeks. Improvement in hand functional capacity, pain intensity, number of painful joints, and the duration and severity of morning stiffness was the same for both groups, suggesting that Arnica may be as effective as NSAID gels in managing these symptoms.3

How to Take Arnica

Based on research, Arnica is most effective when used as a topical application. You can find Arnica-infused creams, gels, oils, or roll-ons designed specifically for external use. 

Gently massage a small amount of the product onto the affected area, such as a bruise, sore muscle or joint, or insect bite. When you apply Arnica topically, it is absorbed through the skin, where bioactive compounds can target inflammation and provide localized relief. 

The dosage has not been established, but based on previous studies, it is considered safe to apply Arnica twice daily for three to six weeks, based on your individual situation.

Potential Side Effects of Arnica

Arnica is generally considered safe for most people when used topically as directed. Because Arnica contains helenalin, which is toxic when ingested in large amounts, it should not be taken orally without consulting your healthcare provider. 

Homeopathic Arnica, a heavily diluted portion of the active ingredients in Arnica, is safe when taken as directed, but is best prescribed by a licensed homeopath. 

Before using Arnica, be aware of potential side effects for both topical and oral use.

Topical Use Side Effects

Some individuals experience mild skin reactions or allergic responses to the topical application of Arnica. These potential side effects and considerations include:

  • Skin irritation: Perform a patch test on a small area of skin before widespread use to check for any adverse reactions.
  • Allergic reactions: If you are allergic to other plants in the Asteraceae family, including sunflowers, marigolds, and ragweed, you may be allergic to Arnica. Allergic reactions could include hives, swelling, or even more severe reactions in rare cases.
  • Open wounds: Do not apply Arnica to open wounds or broken skin, as it may cause further irritation or delay healing.
  • Sensitive skin: If you have sensitive skin, dilute Arnica oil with equal parts of carrier oil, such as olive oil, or use a product specifically formulated for sensitive skin to avoid irritation.

    Oral Use Side Effects

    The digestive system processes substances differently than the skin, and the potential risks of ingesting Arnica may outweigh the potential benefits unless it has been specifically prescribed by your healthcare provider. Side effects may include:

    • Toxicity: Accidental ingestion or deliberate consumption of the Arnica plant or an extract not formulated in a homeopathic dosage can result in poisoning and should be treated as a medical emergency.
    • Gastrointestinal distress: Ingesting Arnica can lead to symptoms such as nausea, vomiting, diarrhea, and stomach cramps. 
    • Cardiovascular effects: Ingesting Arnica may have adverse effects on the cardiovascular system, including irregular heartbeats (arrhythmias) and changes in blood pressure.
    • Nervous system effects: Arnica can affect the central nervous system and may lead to dizziness, confusion, or even seizures in severe cases.
    • Organ damage: Ingesting Arnica can potentially cause damage to organs like the liver and kidneys, particularly when consumed in high amounts.
    • Allergic reactions: Ingesting Arnica could trigger allergic reactions ranging from mild to severe if you are allergic to plants in the Asteraceae family.

    When using Arnica topically or orally, always consult with your healthcare provider if you're using other medications or have underlying health conditions. Do not take Arnica if you are pregnant or breastfeeding.

    How to Maintain a Healthy Inflammation Response

    You can’t avoid bruising and injury altogether, but when you maintain a healthy lifestyle, you give yourself the best chance of keeping inflammation in balance and avoiding acute inflammation that leads to pain and suffering.


    • 1. , "Estimated Rates of Incident and Persistent Chronic Pain Among US Adults, 2019-2020", JAMA Network Open. 1 1. , "Estimated Rates of Incident and Persistent Chronic Pain Among US Adults, 2019-2020", JAMA Network Open.
    • 2. , "Arnica montana gel in osteoarthritis of the knee: an open, multicenter clinical trial", Advances in Therapy. 2 2. , "Arnica montana gel in osteoarthritis of the knee: an open, multicenter clinical trial", Advances in Therapy.
    • 3. , "Choosing between NSAID and arnica for topical treatment of hand osteoarthritis in a randomised, double-blind study", Rheumatology International. 3 3. , "Choosing between NSAID and arnica for topical treatment of hand osteoarthritis in a randomised, double-blind study", Rheumatology International.