Arnica: overview, benefits, dosage, side effects

Arnica is a herb that comes from the Arnica montana flower, which commonly grows in the mountains of Europe and America.¹ A folk medicine since the 16th century,2 arnica is traditionally used to soothe:³

Arnica is applied to the skin, and is available as creams, sprays, massage balms, and bath products. It’s also available as homeopathic pillules (tiny pills) that you swallow.

The European Medicines Agency says that arnica is approved to help relieve bruises, sprains and localised pain.⁴ It has an anti-inflammatory effect inside the body and supports tissue repair, according to a 2016 study in PLoS One. The researchers say one way arnica may work by interacting with the genes responsible for repairing cells.⁵ A 2010 study by Northwestern University, Chicago, found that an ointment of 20% arnica applied twice a day for two weeks faded laser-induced bruises more quickly than the placebo.⁶

Arnica is safe to use when applied to the skin in a thin layer as a cream or gel. Make sure you only apply to areas of unbroken skin. It’s also fine to take homeopathic arnica tablets or spray; in homeopathic medicine, the herb is heavily diluted. However, never use raw arnica – when consumed raw and undiluted, it’s toxic to the body, and applying it directly to the skin can cause irritation.⁷ The following people shouldn’t take arnica:

If bruising lasts longer than three to four days, or get worse after using arnica, speak to your GP.⁹

Some side-effects have been reported, but it’s not known how often they occur. These are:

If you start to experience any of these symptoms, stop taking arnica and see your GP.