Phytotherapy · Topical Bruise & Pain Care · Asteraceae

Arnica

Arnica montana L. (Asteraceae) — the mountain-pasture daisy whose flower heads are the classic remedy for bruises and falls. Its helenalin-type sesquiterpene lactones act through the skin and are studied in bruising, post-surgical swelling and knee osteoarthritis, but the plant is poisonous when swallowed.

21 Primary Refs
12 Properties
Flower Parts Used
✦ Researched
Last Updated October 31, 2026
Primary Source Wikiphyto · NCBI PubMed · Systematic Review
Family Asteraceae
Mountain Herb · Golden Flower Heads

Botanical Overview

Arnica is a herbaceous plant of 20 to 70 cm, found in the mountain pastures of Europe as far as Siberia. A hairy flowering stem rises from a rosette of pale green, hairy, lance-shaped leaves and carries large terminal flower heads of orange-yellow flowers, tubular in the centre and ray-shaped at the edge. The fruits are brown achenes crowned with bristles.

Height20–70 cm
LeavesHairy basal rosette
Flower HeadsLarge, orange-yellow
HabitatMountain pastures
Taxonomic Classification

Taxonomy & Identification

Latin Name
Arnica montana L.
Family
Asteraceae
Common Names
Arnica, Tabac des Vosges, Herbe aux chutes, Quinquina des pauvres
Parts Used
Flower head (capitulum)
Regulatory Status
French Pharmacopoeia, list A (capitulum); recognized by the German Commission E
Ethnobotany & Traditional Use

History & Tradition

Mountain people gave arnica names that say what it was for: herbe aux chutes, the herb of falls, tabac des Vosges, for its use as a snuff-like tobacco, and quinquina des pauvres, the poor man's quinine.

The 1949 Codex listed it among the vulnerary species of the Swiss tea, blended in equal parts with fifteen other herbs, including wormwood, thyme, sage, rosemary and veronica.

Modern work has tested it in bruising, post-surgical swelling and knee osteoarthritis, and has also looked at what it does to skin cells and macrophages. 8118

⚠ For the Skin, Not the Stomach

Arnica is applied to unbroken skin. Swallowing the plant is dangerous, and only homeopathic dilutions are used by mouth.

Timeline

Herb of Falls

Folk Medicine

Mountain communities use it for falls and bruises.

Swiss Tea

1949

Listed in the Codex among the vulnerary species of the Swiss tea.

Official Recognition

Pharmacopoeia

Listed in the French Pharmacopoeia, list A, and recognized by the German Commission E.

Clinical Trials

1998 – 2022

Bruising, surgery and osteoarthritis studies, and cell work on matrix genes. 13

The Key Compounds

Helenalin & Sesquiterpene Lactones — Deep Dive

The pseudoguaianolides, polysaccharides and triterpenes behind arnica's activity.

🧪

Helenalin & Dihydrohelenalin

Pseudoguaianolide lactones esterified with short-chain fatty acids; their profile varies with the plant's origin. They collect in the epidermis. 5

🧫

Immunoactive Polysaccharides

An arabinogalactan stimulates macrophages to release TNF-alpha, and a fucogalactoxyloglucan increases phagocytosis. 3

🧬

Arnidiol & Faradiol

The triterpenic alcohols of the flower head, found alongside phytosterols and carotenoids.

🌼

Flavonoids & Coumarins

Astragaloside, isoquercitroside and luteolin glucoside, with umbelliferone and scopoletin.

Pharmaceutical Preparations

Parts Used & Available Forms

The flower head is used, mainly as skin preparations.

Flower Head

The flowering head (capitulum), listed in the French Pharmacopoeia (list A).

Flower

Whole-Plant Tincture

Teinture-mère of the whole plant.

Liquid Extract

Aerial-Parts Tincture

Teinture-mère of the aerial parts, for external use.

Liquid Extract

Topical Gel

Arnica gel applied to the skin, studied in knee osteoarthritis. 1

Topical

Topical 20% Preparation

A 20% arnica product tested on laser-induced bruising. 17

Topical

Homeopathic Dilutions

Dilutions from D1 to D4, and from 2 CH up to 15 CH in laboratory work. 18

Homeopathic

Clinical Dosimetry

Dosages

No standardized usual dosage has been established for arnica; dosing should be guided by a qualified practitioner.

Phytochemistry

Composition

Sesquiterpene lactones lead the profile, supported by triterpenes, flavonoids and immunoactive polysaccharides.

Flower Head — Terpenoids & Lipids

Sesquiterpene LactonesHelenalin and dihydrohelenalin (pseudoguaianolides), esterified with short-chain fatty acids 5
Major
Triterpenic AlcoholsArnidiol and faradiol
Present
Essential OilButter-like in consistency: palmitic, linoleic, myristic and linolenic acids, n-alkanes and polyynes
Present
PhytosterolsPresent in the flower head
Present
CarotenoidsPresent in the flower head
Present

Phenolics & Polysaccharides

FlavonoidsAstragaloside, isoquercitroside, quercetol-3-glucogalacturonide and luteolin glucoside
Present
Phenolic AcidsPresent in the flower head
Present
TanninsPresent in the flower head
Present
CoumarinsUmbelliferone and scopoletin
Present
PolysaccharidesArabinogalactan (arabino-3,6-galactane) and fucogalactoxyloglucan 3
Immunoactive

Plant Properties — Pharmacodynamics

Twelve pharmacodynamic properties define arnica, centered on bruising, inflammation and skin repair.

12 Properties Anti-Inflammatory Anti-Ecchymotic Clinical Trials
🔥

Anti-Inflammatory & Antirheumatic

Reduced inflammation in animal work and eased knee osteoarthritis in an open trial. 41

💪

Topical Analgesic

Relieved knee osteoarthritis pain on the WOMAC index. 1

⚡

Antineuralgic

Used on the skin over painful nerves in neuralgia.

🧴

Topical Muscle Relaxant

Phonophoresis of arnica acted on acute muscle inflammation in rats. 2

🟣

Anti-Ecchymotic

Reduced bruising after rhinoplasty and after laser treatment. 1117

🩹

Wound Healing

Promotes skin repair, an action compared to that of echinacea.

🦠

Antibacterial & Antifungal

Active against bacteria and fungi in laboratory tests.

🛡️

Immunostimulant

Its polysaccharides raise TNF-alpha release by macrophages and increase phagocytosis in cell cultures. 3

🌿

Spasmolytic

Counters histamine-induced spasm.

🎯

Skin Accumulation

Sesquiterpene lactones collect in the epidermis after application of the tincture. 5

🧫

Antileishmanial

The tincture and isolated lactones acted against four Leishmania species in studies. 67

⚠️

Contact Sensitization

The lactones cause delayed-type allergic contact dermatitis in people who handle the flowers. 21

Clinical Applications

Clinical Indications

Arnica is used on the skin for bruising, swelling and joint pain, with trials in surgery and osteoarthritis.

🟣
Bruising & Post-Traumatic Swelling
Primary Indication
  • Trauma & Surgery: pain, edema and ecchymoses after injury or operation. 8
  • Rhinoplasty: perioperative arnica was studied for less bruising. 11
  • Laser-Induced Bruising: a 20% topical preparation sped up resolution in a rater-blinded randomized trial. 17
🏥
Post-Surgical Pain & Swelling
Clinical Indication
  • Carpal Tunnel Surgery: arnica was used to relieve pain afterward. 9
  • Knee Surgery: less swelling than placebo in homeopathic arnica trials. 10
  • Mastectomy: fewer hematomas and seromas in a randomized trial. 16
🦵
Osteoarthritis, Neuralgia & Muscle Pain
Clinical Indication
  • Knee Osteoarthritis: an open multicenter trial of arnica gel. 1
  • Neuralgia: a topical traditional indication.
  • Exercise Pain: one study suggested topical arnica may increase post-exercise muscle pain. 15
⚖️
Mixed Evidence & Other Uses
Evidence Limits
  • Systematic Review: homeopathic dilutions were no better than placebo. 13
  • Aortic Valve Surgery: an arnica and bryonia combination had no effect. 14
  • Postpartum Bleeding: a preliminary trial with homeopathic dilutions. 12
  • Mouth & Throat: gargles for tonsillitis and stomatitis.
Pharmacodynamics

Mode of Action

Arnica appears to work through macrophages and the extracellular matrix during tissue repair.

🧫

Macrophages & Matrix

Arnica acts on macrophages and the extracellular matrix, stimulating cell adhesion and migration during tissue repair. 18

🧬

Fibronectin Gene Upregulation

A low homeopathic dilution (2 CH, equal to 10⁻⁸ mol/L of sesquiterpene lactones) raised the expression of matrix protein genes, mainly fibronectin, and the effect was reported up to 15 CH. 18

🎯

Epidermal Accumulation

Helenalin and dihydrohelenalin collect in the epidermis, which may explain the benefit in local skin conditions. 5

🛡️

Immune Polysaccharides

Arabino-3,6-galactane stimulates TNF-alpha release by macrophages, and fucogalactoxyloglucan increases phagocytosis. 3

🦠

Antileishmanial Action

The tincture and its isolated lactones were active against L. donovani, L. infantum, L. braziliensis and L. tropica. 67

Clinical Safety

Safety & Interactions

Arnica is well tolerated on unbroken skin, but swallowing the plant can be fatal.

⚠ Genuine, Serious Risks of Oral Use

Read Before Using Arnica

  • Swallowing: hallucinations, digestive upset, severe gastroenteritis, heart toxicity, nervousness, a rapid pulse and muscle weakness that can be fatal. A handful of flowers is potentially lethal.
  • Warfarin: interactions with warfarin have been described, although one randomized trial found no effect on coagulation. 2019
  • Allergy: delayed-type contact dermatitis from the sesquiterpene lactones, reported in people handling the flowers. 21
  • Damaged skin: prolonged use, or use on leg ulcers, may cause swollen, pustular dermatitis or eczema.
⚠️

Adverse Effects & Precautions

  • Topical Tolerance: generally good, and not irritating in clinical tests. 21
  • Contact Dermatitis: a delayed-type allergic reaction is possible.
  • Prolonged Use: may cause dermatitis or eczema.
  • Muscle Pain: one study suggested topical arnica may increase post-exercise muscle pain. 15
🚫

Contraindications & Interactions

  • Oral Use: not advised in any form other than homeopathic dilutions.
  • Anticoagulants: check with a prescriber if you take warfarin. 20
  • Coagulation: no effect was found in a randomized trial. 19
  • Regulatory Status: French Pharmacopoeia, list A (capitulum); recognized by the German Commission E.
Clinical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before using arnica, particularly if you take blood thinners, have open wounds or leg ulcers, or are allergic to Asteraceae plants.
Common Questions

Frequently Asked Questions

What is arnica used for?
Arnica (Arnica montana) flower heads are applied to the skin for bruises, sprains and falls, for pain and swelling after injury or surgery, and for neuralgia and osteoarthritic joints. Gargles of the diluted tincture have been used for tonsillitis and mouth inflammation.
Does arnica help bruises?
A perioperative arnica regimen was studied for bruising after rhinoplasty, and a rater-blinded randomized trial found that a 20% topical arnica preparation accelerated the resolution of laser-induced bruising.
Is arnica safe to take by mouth?
No. Swallowing the plant can cause hallucinations, digestive upset, severe gastroenteritis, heart toxicity, nervousness, a rapid pulse and muscle weakness that can be fatal. A handful of flowers is potentially lethal. Arnica is applied to unbroken skin, and only homeopathic dilutions are taken by mouth.
Does arnica work after surgery?
Results are mixed. Arnica was studied for pain after carpal tunnel surgery, for swelling after knee surgery and for fewer hematomas and seromas after mastectomy. A systematic review found that homeopathic dilutions were no better than placebo, and a homeopathic arnica and bryonia combination had no effect after aortic valve surgery.
Can arnica help knee osteoarthritis?
An open multicenter trial of arnica gel in knee osteoarthritis reported improvement on the WOMAC index. The trial was uncontrolled, so the result needs confirmation in randomized studies.
What is helenalin?
Helenalin and dihydrohelenalin are the pseudoguaianolide sesquiterpene lactones of arnica, esterified with short-chain fatty acids. They accumulate in the epidermis, which may explain the benefit in skin conditions, and they are also the cause of contact allergy.
Does arnica interact with blood thinners?
One randomized trial found no effect of arnica on blood coagulation, yet interactions with warfarin have been described. People on anticoagulants should check with their prescriber before using arnica.
Can you be allergic to arnica?
Yes. The sesquiterpene lactones can cause delayed-type (type IV) allergic contact dermatitis, reported in people who handle the flowers. Prolonged use, or use on leg ulcers, may cause swollen, pustular dermatitis or eczema.
What is the usual arnica dosage?
No standardized usual dosage has been established for arnica; dosing should be guided by a qualified practitioner. Studies used a topical gel or a 20% arnica preparation on the skin, and homeopathic dilutions from D1 to D4 and from 2 CH up to 15 CH.
Sources

Bibliography

↑1. Knuesel O, Weber M, Suter A. Arnica montana gel in osteoarthritis of the knee: an open, multicenter clinical trial. Adv Ther. 2002;19(5):209–218.
PubMed: PMID 12539881 →
↑2. Alfredo PP, Anaruma CA, Pião AC, et al. Effects of phonophoresis with Arnica montana onto acute inflammatory process in rat skeletal muscles: an experimental study. Ultrasonics. 2009;49(4–5):466–471.
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↑3. Puhlmann J, Zenk MH, Wagner H. Immunologically active polysaccharides of Arnica montana cell cultures. Phytochemistry. 1991;30(4):1141–1145.
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↑4. Macêdo SB, Ferreira LR, Perazzo FF, et al. Anti-inflammatory activity of Arnica montana 6cH: preclinical study in animals. Homeopathy. 2004;93(2):84–87.
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↑5. Jürgens FM, Herrmann FC, Robledo SM, Schmidt TJ. Dermal absorption of sesquiterpene lactones from Arnica tincture. Pharmaceutics. 2022;14(4):742.
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↑6. Robledo SM, Murillo J, Arbeláez N, et al. Therapeutic efficacy of Arnica in hamsters with cutaneous leishmaniasis caused by Leishmania braziliensis and L. tropica. Pharmaceuticals (Basel). 2022;15(7):776.
PubMed: PMID 35890075 →
↑7. Robledo SM, Vélez ID, Schmidt TJ. Arnica tincture cures cutaneous leishmaniasis in golden hamsters. Molecules. 2018;23(1):150.
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↑8. Iannitti T, Morales-Medina JC, Bellavite P, et al. Effectiveness and safety of Arnica montana in post-surgical setting, pain and inflammation. Am J Ther. 2016;23(1):e184–e197.
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PubMed: PMID 11892685 →
↑10. Brinkhaus B, Wilkens JM, Lüdtke R, et al. Homeopathic arnica therapy in patients receiving knee surgery: results of three randomised double-blind trials. Complement Ther Med. 2006;14(4):237–246.
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↑11. Chaiet SR, Marcus BC. Perioperative Arnica montana for reduction of ecchymosis in rhinoplasty surgery. Ann Plast Surg. 2016;76(5):477–482.
PubMed: PMID 25954844 →
↑12. Oberbaum M, Galoyan N, Lerner-Geva L, et al. The effect of the homeopathic remedies Arnica montana and Bellis perennis on mild postpartum bleeding — a randomized, double-blind, placebo-controlled study — preliminary results. Complement Ther Med. 2005;13(2):87–90.
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↑13. Ernst E, Pittler MH. Efficacy of homeopathic arnica: a systematic review of placebo-controlled clinical trials. Arch Surg. 1998;133(11):1187–1190.
PubMed: PMID 9820349 →
↑14. Cornu C, Joseph P, Gaillard S, et al. No effect of a homoeopathic combination of Arnica montana and Bryonia alba on bleeding, inflammation, and ischaemia after aortic valve surgery. Br J Clin Pharmacol. 2010;69(2):136–142.
PubMed: PMID 20233176 →
↑15. Adkison JD, Bauer DW, Chang T. The effect of topical arnica on muscle pain. Ann Pharmacother. 2010;44(10):1579–1584.
PubMed: PMID 20807867 →
↑16. Sorrentino L, Piraneo S, Riggio E, et al. Is there a role for homeopathy in breast cancer surgery? A first randomized clinical trial on treatment with Arnica montana to reduce post-operative seroma and bleeding in patients undergoing total mastectomy. J Intercult Ethnopharmacol. 2017;6(1):1–8.
PubMed: PMID 28163953 →
↑17. Leu S, Havey J, White LE, et al. Accelerated resolution of laser-induced bruising with topical 20% arnica: a rater-blinded randomized controlled trial. Br J Dermatol. 2010;163(3):557–563.
PubMed: PMID 20412090 →
↑18. Marzotto M, Arruda-Silva F, Bellavite P. Fibronectin gene up-regulation by Arnica montana in human macrophages: validation by real-time polymerase chain reaction assay. Homeopathy. 2020;109(3):140–145.
PubMed: PMID 32311747 →
↑19. Baillargeon L, Drouin J, Desjardins L, et al. Les effets de l'Arnica montana sur la coagulation sanguine. Essai clinique randomisé. Can Fam Physician. 1993;39:2362–2367.
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↑20. Heck AM, DeWitt BA, Lukes AL. Potential interactions between alternative therapies and warfarin. Am J Health Syst Pharm. 2000;57(13):1221–1227.
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↑21. Final report on the safety assessment of Arnica montana extract and Arnica montana. Int J Toxicol. 2001;20(Suppl 2):1–11.
PubMed: PMID 11558636 →

Additional Sources

Wichtl M, Anton R. Plantes thérapeutiques: Tradition, pratique officinale, science et thérapeutique. Cachan: Éditions Tec & Doc; 1999. p. 47.