Arnica is a daisy-like plant with yellow flowers. Homeopathic arnica uses diluted tinctures to speed wound healing and relieve menopausal symptoms, but the evidence of its effectiveness is very scarce. Read on to learn more.
What Is Arnica?
Arnica (Arnica montana L.), also known as mountain daisy, mountain tobacco, and leopard’s bane, is a plant with orange-yellow flowers that belongs to the same family as sunflowers, dandelions, daisies, and marigolds (Asteraceae) [1, 2].
Arnica grows best at an altitude of 500 – 2,500 meters and is native to the meadows and mountainous regions of Europe, western North America, and northern Asia. Because arnica is endangered in several European countries, its cultivation has increased but the harvesting of wild plants is not allowed [1, 2].
The plant has been used for centuries to reduce the inflammation and pain of [1, 2]:
- Sprains
- Contusions
- Bruises
- Wounds
Today, herbal and homeopathic arnica preparations are applied to the skin for [1, 2]:
- Soft tissue injuries (e.g., smashed fingers)
- Sprains, strains, fractures, and contusions
- Arthritis
- Muscle soreness
- Post-surgical bruises and swelling
Arnica can also be formulated in oral homeopathic pills that are mainly used for [3]:
- Mouth, gum, and throat inflammation
- Headaches
- Diabetic eye damage
- Post-surgical bruises and swelling
- Muscle soreness
The German Commission E has only approved the use of topical arnica (creams, gels, ointments) for injuries, consequences of accidents, and inflammation (mouth and throat, insect bites, boils, veins). The FDA considers oral arnica unsafe due to its toxicity and the Canadian Government prohibits its use as a food ingredient [1, 3].
It’s important not to confound Arnica montana with other plants popularly known as “arnicas”, such as Brazilian (Solidago chilensis and Lychnophora spp.) and Mexican (Heterotheca inuloides) arnicas. They belong to the same family and are also used in traditional medicine, but may have different active compounds and applications [4, 5, 6].
What is Homeopathic Arnica?
Arnica is often used as a homeopathic remedy. Homeopathic remedies are prepared by diluting the active compound with alcohol or water several times. The FDA doesn’t approve homeopathic arnica (or any other homeopathic preparations) for any conditions.
What’s the Difference Between Herbal and Homeopathic Arnica?
It’s very important to discriminate between herbal preparations, such as arnica creams and gels, and homeopathic ones. Homeopathic remedies are not the same as herbal tinctures, extracts, and other products used in herbal medicine in an evidence-based way.
Sometimes herbal products are combined with homeopathic remedies. But homeopathy relies on completely different principles, such as the “vital force” and “like cures like” to explain how the remedies supposedly act.
Homeopathy also uses a lot of substances that are toxic in normal, oral doses, including arnica. Substances are greatly diluted in a process called “dynamization” or “potentisation” and thought to exert an energetic effect on the body.
Homeopathic preparations are commonly critiqued for using such high dilutions that they contain only a few or no molecules of the active compound. Homeopathy does not consider that the effects of the remedies come from the active components of the substance used.
Scientific evidence does not back up the claims made by homeopathy. Indeed, a meta-analysis concluded that homeopathic remedies had no effect beyond the placebo effect [7].
Homeopathic Dilutions and Doses
Homeopathic dilutions are written as a number followed by a letter (e.g., 30C). The number is the number of times the diluting process was performed. The letter represents the dilution factor, or how much the substance was diluted [8]:
- X or D: 1/10 means it was diluted 10 times and contains 10% of the active compound; 1 part of extract per 10 of alcohol or water
- C: 1/100
- M: 1/1,000,000
So, a homeopathic arnica remedy labeled as 10X would contain only about 0.000000001% of arnica. One labeled as 30C would contain much less, as it would mean that the substance was 30 times diluted by 100.
Because homeopathic arnica preparations are not standardized, it’s almost impossible to compare the doses of different products. But it’s worth noting that most of them probably do not contain any arnica at all. The upside of this is that, unless adulterated, they act similar to placebo and won’t cause serious side effects or drug interactions. However, the extremely low concentration of homeopathic dilutions is among the reasons why most doctors are highly skeptical of homeopathy in general [1].
What do People Use Homeopathic Arnica For?
Homeopathic arnica has not been approved by the FDA for medical use and generally lacks solid clinical research. Speak with your doctor before using it, and never use it in place of something your doctor recommends or prescribes.
Insufficient Evidence for:
1) Wound Healing
In a clinical trial on 88 people undergoing bunion removal, homeopathic arnica (10 D4 pills 3x/day) was as effective as an anti-inflammatory drug (diclofenac 50 mg) at reducing the redness, swelling, and heat of inflamed wounds [9].
Homeopathic arnica dilutions enhanced wound healing and the production of wound-healing proteins by white blood cells (macrophages) in a cell-based study. However, the alcohol used in the dilutions could have contributed to these effects [10, 11].
A single clinical trial and a cell-based study cannot be considered sufficient evidence that homeopathic arnica improves wound healing. More robust studies are needed.
2) Menopausal Symptoms
In a clinical trial on over 100 menopausal women (funded by Boiron), a homeopathic mixture containing arnica (4C) and 4 other remedies reduced hot flashes better than placebo over 12 weeks [12].
Further studies with a lower risk of bias should confirm this preliminary result.
Possibly Ineffective for:
1) Pain Relief
The evidence isn’t convincing, as homeopathic arnica remedies had either no effect or very slightly improved pain in most of the mentioned studies. Its effects were mostly comparable to the placebo, with some exceptions. Additionally, several of the studies were too small, lacked appropriate controls, or were funded by the company selling the preparation.
However, pain is especially susceptible to the placebo effect, which shouldn’t be overlooked. The placebo effect can be looked at as therapeutic. It may reduce the use of dangerous painkillers and train people to become active agents of their therapy [13].
The placebo effect, and most probably the pain-relieving effects of arnica, also depend on the healing environment and the practitioner you may come into contact with [13].
Arthritis Pain
A homeopathic ointment with arnica and other components applied 3x/day reduced pain and increased shoulder mobility in a clinical trial on 41 people with shoulder arthritis. However, there was no placebo group in the study [14].
In a clinical trial on 30 people with low-back pain caused by arthritis, 2 homeopathic tablets of arnica (6C) and other plants 2x/day combined with physiotherapy outperformed placebo. They improved pain and disability after 4 weeks but didn’t reduce the use of other painkillers [15].
Pain from Traumatic Injuries
Traumeel, a homeopathic preparation with arnica (3D) and other plants, reduced pain as effectively as conventional medicines in an observational study on over 100 people with ankle, hand, or knee injuries [16].
Surgical Pain
A 5% arnica ointment combined with homeopathic arnica tablets (6D) 1x/day for two weeks reduced pain but not swelling in a clinical trial on 37 people undergoing carpal tunnel syndrome surgery. But homeopathic arnica tablets alone (6C or 30C) were not better than placebo at reducing pain, bruising, or swelling after this procedure in another trial on 64 people [17, 18].
A homeopathic complex with arnica taken before surgery and for 3 days after wasn’t more effective than placebo at reducing pain in a clinical trial of 158 people undergoing knee ligament reconstruction. Similarly, homeopathic arnica (30X) before and after knee surgery only slightly reduced pain and swelling in 21% of the cases in trials on over 300 people [19, 20].
One clinical trial on over 100 people undergoing tonsil removal claimed that homeopathic arnica (30C tablets 6x/day) reduced their pain when taken for a week after surgery. But when the data were analyzed, there was no difference to placebo [21, 22].
In a clinical trial on over 100 people who had their wisdom teeth removed, homeopathic arnica (200C 2x/day) was worse than an antibiotic (metronidazole) and placebo at reducing pain and swelling. In another trial on 24 people, a homeopathic complex with arnica (30D) didn’t improve pain nor inflammation after wisdom teeth removal [23, 24].
In a clinical trial on 88 people undergoing bunion removal, homeopathic arnica (10 D4 pills 3x/day) reduced pain less effectively than an anti-inflammatory drug (diclofenac 50 mg). However, it did reduce wound irritation and improved mobility similar to the drug and with fewer side effects [9].
In a clinical trial on 73 women, arnica (30C) taken before and for 5 days after uterus removal surgery (hysterectomy) didn’t reduce pain nor infections better than placebo [25].
Muscle Soreness
In 2 trials of 82 runners, homeopathic arnica (5 30C pills 2x/day for 4 days) lowered muscle soreness immediately after a marathon. However, homeopathic arnica (30X and 200C) before and after long-distance runs was not better than placebo in 2 clinical trials on over 500 people [26, 27, 28].
Similarly, homeopathic arnica (30C 3x/day) didn’t improve muscle soreness after bench-stepping exercises in two clinical trials on over 100 people [29, 30].
In a clinical trial on 53 people, a homeopathic arnica cream (1X) wasn’t better than placebo at improving muscle soreness after doing calf raises. On the contrary, it worsened muscle soreness slightly one day after the exercise [31].
2) Bruises
In a small trial on 11 people, homeopathic arnica (30C) before and after being bruised didn’t have any effect. In another trial, homeopathic arnica (10M) taken after bruising reduced bruise size more than placebo in 6 out of 13 cases [32].
Plastic Surgery
Homeopathic arnica (1M) 3x/day for 3 – 4 days slightly accelerated the healing of bruises caused by plastic surgery in a clinical trial on 22 people. But it only improved swelling on day 2 in another trial of 48 people [33, 34, 35].
The application of pads with homeopathic arnica (50M) and wild rosemary improved bruises in a clinical trial on 27 people undergoing eye surgery. However, there was no control group [36].
Homeopathic arnica (1M) taken before eyelid surgery and for 3 days after (12C 3x/day) didn’t reduce bruises in a trial of 30 people [37].
In a clinical trial on 29 people with bruises from face-lift surgery, homeopathic arnica tablets (3x/day) didn’t improve pain or bruise color after 4 days. They only caused a slight bruised surface reduction that couldn’t be detected without a computer [38].
Other Medical Procedures
In a clinical trial on over 100 people undergoing vein stripping surgery, homeopathic arnica (5C) before and after surgery didn’t prevent or reduce bruises [39].
Homeopathic arnica pills (6C or 30C 1x/day) for one week before and two weeks after carpal tunnel syndrome surgery didn’t prevent bruising or reduce swelling in a clinical trial on 64 people [18].
A pulsed dye laser is routinely used to remove skin birthmarks and help heal bruised skin. A homeopathic ointment with arnica (1X) wasn’t better than placebo at preventing or improving bruises in a clinical trial on 19 people [40].
Because the results were mostly negative except in a few studies with multiple flaws (small populations, lack of controls, high risk of bias), homeopathic arnica is possibly ineffective for bruises based on the existing evidence.
3) Bleeding
In a clinical trial on 40 women who recently gave birth, 3 homeopathic pills of arnica (6C or 30C) combined with 3 homeopathic pills of the common daisy (Bellis perennis) every 5 hours for 1 day and 3x/day for 2 additional days reduced blood loss [41].
In a clinical trial on 53 women undergoing breast cancer surgery, 5 drops of homeopathic arnica (1000K, 3x/day) for 4 days slightly reduced bleeding. However, the study was funded by Boiron and its design was flawed [42, 43].
A combination of homeopathic arnica and bryonia (5C 2x/day) for 5 days after heart surgery didn’t reduce bleeding, inflammation, pain, or poor blood flow in a clinical trial on 92 people [44].
Again, the results are mixed and the studies supporting this potential benefit had several flaws.
Limitations and Caveats
Study Results
For most health benefits, studies reported a mix of positive and negative results. Those using homeopathic remedies most frequently showed no differences between the application of arnica and the placebo.
Study Design
A lot of the studies were done on a few people (30 or less), which can produce unreliable results.
Some studies lacked an appropriate placebo control or had no controls at all [45, 14, 36, 16, 46, 47, 9, 35].
The effects of arnica on infections and breathing have only been tested in animal and cell studies. Clinical trials in humans are needed to confirm them.
Study Funding and Conflict of Interest
Several of the studies were funded by companies selling arnica preparations (Bioforce, Boiron, Alpine Pharmaceuticals, Similasan, Cearna) or done by employees of these companies [45, 48, 38, 10, 42, 12, 36].
Takeaway
Arnica generally refers to Arnica montana L., also known as mountain daisy, mountain tobacco, or leopard’s bane. It has long been a part of traditional medicine, typically used topically to relieve pain.
Homeopathic arnica formulations are heavily diluted tinctures taken by mouth. These are generally diluted to such an extent that they effectively contain no arnica at all. It is unsurprising, then, that meta-analyses of clinical research has found that homeopathic arnica is likely no more effective for any purpose than a placebo. Furthermore, many clinical studies on homeopathic arnica suffer from serious design flaws and high risk of bias.
