Arnica: overview, benefits, dosage, side effects

Find out all about arnica, including what it does, the benefits of taking it and how much you might need

Written by Jack Feeney on December 17, 2018 Reviewed by Fiona Hunter on January 4, 2019

Overview

What is arnica and what does it do?

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 16^th century,² arnica is traditionally used to soothe:³

• bruises
• sprains
• muscle pain

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.

Benefits of arnica

What does arnica do in the body?

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

Dosage

How much arnica is safe to take?

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:

• children under the age of 12 – it has not been proven safe
• anyone who is allergic to plants in the Asteraceae family
• pregnant or breastfeeding women – it has not been proven safe for these groups⁸

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

Side-effects

What are the side-effects of taking or using arnica?

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

• itching
• redness of the skin
• eczema¹⁰

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

Shop Arnica Advice is for information only and should not replace medical care. Please check with your GP before trying any remedies.

Sources

1. Encyclopedia.com. Arnica

2. As above

3. European Medicines Agency. Arnica flower

4. As above

5. Marzotto M, et al. Arnica montana Stimulates Extracellular Matrix Gene Expression in a Macrophage Cell Line Differentiated to Wound-Healing Phenotype 6. Leu S, et al. Accelerated resolution of laser-induced bruising with topical 20% arnica: a rater-blinded randomized controlled trial 7. ScienceDirect. Arnica Montana 8. European Medicines Agency. Community herbal monograph on Arnica montana L.,flos 9. European Medicines Agency. Arnicae flos 10. As Source 8