Arnica (Arnica montana) is a mountain flower. Herbal arnica is used in gels and creams on the skin for bruises and sore muscles. Homeopathic arnica, taken by mouth, is a different product.
Also known as: Arnica montana, arnica gel, homeopathic arnica, mountain arnica.
A hand osteoarthritis trial used a gel with 50 g of arnica tincture per 100 g for 21 days (Widrig 2007). These are study protocols, not a recommendation.
In the EU, EMA concluded that arnica flower preparations applied to the skin can be used to relieve bruises, sprains and localized muscle pain, from age 12. EMA bases this on long-standing ("traditional") use: there is not enough evidence from clinical trials, but the effect is plausible and the herb has been used safely this way for at least 30 years, including at least 15 years in the EU. EMA said studies suggested less pain and bruising, but small size and lack of controls prevented firm conclusions (EMA).
What studies show: in 204 people with hand osteoarthritis, an arnica gel was not worse than 5% ibuprofen gel for pain and hand function over 21 days (Widrig 2007). For homeopathic arnica after surgery, a 2021 meta-analysis found a small effect over placebo that was not statistically significant (Gaertner 2021).
Safety: EMA reports allergic skin reactions such as itching, redness and eczema, frequency unknown. Side effects were similar for arnica and ibuprofen gels (about 5% and 6% of patients) in the hand trial (Widrig 2007). The sources here do not describe drug interactions.
We could not find a single published half-life or time to peak for arnica that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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