Arnica Homeopathic Medicine: Overview, Uses, and Benefits

Discovered in the 1700s by Samuel Hahnemann, homeopathic medicine is a controversial form of alternative medicine. Homeopathy involves administering highly diluted herbs and substances to promote healing (2).

It’s based around several main principles, including (2, 3):

1. Like cures like. If something causes side effects in a healthy person, it will treat an unhealthy person.
2. Minimum dose principle. The smallest dose yields the biggest benefits.
3. Water memory. The more diluted a substance is, the more potent it is.

In fact, the solutions can be so diluted that there’s very little compound remaining, although it’s still believed to be effective. Typically, homeopathic remedies are provided in pill, capsule, or tincture form (2).

Given the high prevalence of addiction to painkillers, many people turn to arnica as an alternative form of treatment.

Typically applied to the skin as a gel, ointment, salve, poultice, tincture, or oil, it’s believed to reduce pain and inflammation. It’s also found in capsule and tablet forms that are taken orally (1, 4).

Homeopathic arnica is usually diluted 10–30 times and uses the labels “C” for centesimal (more diluted) or “D” for decimal dilutions (less diluted). For example, a C10 and D10 dilution would indicate arnica was diluted 10 times at a dilution of 1-to-100 and 1-to-10, respectively (5).

Ultimately, the amount of arnica in most homeopathic solutions is almost nonexistent. Despite being a poisonous herb, homeopathic arnica is believed to be safe due to its high dilution (3).

Summary

Unlike the toxic arnica plant, homeopathic arnica contains trace amounts of arnica and is likely safe when consumed in small amounts. Many proponents of homeopathy recommend highly diluted arnica to treat pain and inflammation.

There are many arnica-related health claims. Due to the high level of skepticism from the medical community and fact that most initial studies showed limited efficacy, few modern studies exist in the literature.

Pain management

Arnica is well known for its anti-inflammatory properties. It contains a wide array of inflammation-fighting plant compounds, such as sesquiterpene lactones, flavonoids, and phenolic acids. As such, it’s believed to help with pain management (1).

In a 2014 review study, applying topical arnica gel was found to be as effective as topical ibuprofen, a common pain reliever, at reducing osteoarthritis pain and improving physical function (6).

Another 2003 study found that taking 5 pills of arnica D30 twice daily significantly improved muscle soreness (7).

However, multiple studies showed no improvements when using C30 doses, though some of the research is on the older side (8, 9).

Interestingly, a 2010 study found that topical arnica with a potency of 7% of D1 gel led to a significant increase in calf pain 24 hours after performing calf exercises, further putting into question the effectiveness of homeopathic arnica (10).

Beyond this, the majority of studies and reviews have concluded that arnica is not effective for pain management, especially when delivered in tablet form. Nonetheless, the large inconsistencies in dosages and flaws in study design warrant up-to-date, higher quality research (11, 12, 13).

Skin bruising

Bruises occur when tiny blood vessels burst due to some form of trauma, such as surgery or hitting your skin against an object. Historically, homeopathic arnica has been used to treat bruises, although research is mixed.

In one study, participants with small bruises were treated with either 20% arnica gel, 5% vitamin K, a combination of 1% vitamin K and 0.3% retinol, or a placebo. After 14 days, the arnica group had significantly less bruising compared with the placebo and combined group (14).

Another 10-day study found significant improvements in bruising and swelling post-rhinoplasty when arnica cream (D1 homeopathic solution) was applied topically, compared with the placebo group. Yet, the other treatment (mucopolysaccharide polysulfate cream) was equally effective (15).

However, numerous older studies have shown no benefit to using arnica in the treatment of bruises. Though, these studies used much smaller doses of arnica, suggesting that highly diluted arnica — the goal of homeopathy — is ineffective (16, 17, 18, 19).

Hair loss

Arnica is widely used in homeopathic medicine to promote hair growth, prevent hair loss, and treat dandruff. It’s commonly found as an oil, shampoo, or hydrogel, a 99% water-based product.

Despite many anecdotal claims, limited research supports its ability to treat hair loss and promote hair growth. In fact, one case study in a 26-year-old woman with hair loss reported no improvements in hair growth after using homeopathic arnica oil (20).

In theory, applying arnica oil may help reduce scalp irritation and inflammation due to its anti-inflammatory properties, which may allow for a better environment for hair growth. However, more research is needed.

Summary

Topical arnica gel may improve skin bruising and reduce osteoarthritis pain and inflammation. Beyond this, limited research supports the use of homeopathic arnica for hair growth, muscle soreness, and other uses.

Before trying arnica, it’s important to be aware of potential risks and side effects.

Safety and side effects

Arnica — either in whole plant form or large amounts of undiluted arnica (for example, plant extracts or oils) — is poisonous and should be avoided.

Consuming it can lead to serious side effects, such as nausea, vomiting, shortness of breath, high blood pressure, irregular heartbeat, coma, or even death (21, 22, 23, 24).

When arnica is highly diluted in homeopathic formulations, it’s likely safe to take orally. However, it’s best to avoid oral ingestion of homeopathic arnica (i.e., oils, tablets, tinctures) or other products containing arnica, including mouthwash unless under medical supervision.

What’s more, children, people with allergies to the Asteraceae family, those on certain medications, and women who are pregnant or breastfeeding should avoid taking arnica due to potentially life threatening safety concerns (21, 24, 25).

Overall, it’s critical to check with your healthcare provider before taking oral arnica, even if it’s highly diluted.

Additionally, topical arnica gel can lead to skin dryness, itchiness, rash, and increased pain. Certain products, such as bubble bath products, creams, and shampoos, may also cause these side effects. Avoid applying arnica gel or creams to broken skin or open wounds (21, 24, 26).

At-risk populations

All people should avoid ingesting the whole arnica herb due to its high toxicity.

Moreover, women who are pregnant or breastfeeding should avoid ingesting arnica in all forms. In one case study, a 9-day-old breastfed infant experienced a large decrease in red blood cells after its mother began drinking arnica extract tea (27).

Those who have a ragweed allergy or an allergy to other members of the Asteraceae family should avoid arnica, as these belong to the same plant family (24, 28).

Finally, those with certain medical conditions, such as inflammatory bowel disease, high blood pressure, and arrhythmias, should avoid its use (24).

Drug interactions

Though there’s limited research available, arnica may interact with antiplatelet medications (e.g., Aspirin and Plavix) and herbs (e.g., clove, garlic, ginger, ginkgo, and ginseng) (24).

It’s best to consult your healthcare provider before using homeopathic arnica orally or topically.

Summary

Homeopathic arnica is highly diluted and likely safe for use in small amounts. However, those who are pregnant or breastfeeding, have ragweed allergies, or taking certain medications should avoid its use. Always speak to your healthcare provider first.

Currently, there are no standard recommendations for homeopathic arnica for treating bruises or pain.

Further, most oral homeopathic arnica products come in widely varying doses. The most common include C12, C30, and C200 — all of which are extremely diluted.

For topical arnica gels, be sure to follow the instructions on the label and only use highly diulted products. Most over-the-counter products can be applied topically 2–3 times daily for up to 3 weeks.

It’s best to store all forms of arnica in a cool, dry environment away from direct sunlight.

However, arnica products are not regulated in the same way as medications, and the stated quantities on the package may not be accurate. Therefore, do not use more than indicated, and be sure to run this by your healthcare provider first (24).

Summary

Always follow the directions on the label or those of your healthcare provider when taking homeopathic arnica.

Arnica is a perennial herb that’s used in many homeopathic products, such as tablets, creams, and gels.

Some small studies show promise in using topical homeopathic arnica gel to treat bruises and osteoarthritis pain. However, there’s limited research to show it helps with hair growth, muscle pain, and other claims.

Though the plant is toxic, taking homeopathic arnica is likely safe when consumed in small amounts because it’s highly diluted. Those who are pregnant, breastfeeding, allergic to ragweed, or on antiplatelet medications should avoid taking homeopathic arnica.

If you’re interested in trying homeopathic arnica, be sure to speak with a healthcare professional first.