Arnica for Bruising: Evidence and Recommendations
Topical arnica may help accelerate the resolution of bruising, but evidence is mixed and generally of low quality. While some studies show benefit, others show no significant difference compared to placebo.
Efficacy of Arnica for Bruising
Research Evidence
- A 2010 randomized controlled trial found that topical 20% arnica ointment reduced bruising more effectively than placebo (white petrolatum) and more effectively than low-concentration vitamin K formulations 1
- However, contradictory evidence exists:
- A 2002 randomized, double-blinded, placebo-controlled study found no significant difference between topical arnica and vehicle in either prevention or resolution of laser-induced bruising 2
- A 2003 randomized placebo-controlled trial in hand surgery patients showed no advantage of homeopathic arnica over placebo for reducing postoperative pain, bruising and swelling 3
Mechanism of Action
Arnica montana appears to have anti-inflammatory properties that may help with bruising:
- In a UVB radiation-induced skin-burn model in mice, topical arnica montana reduced inflammatory response by:
- Decreasing edema
- Inhibiting myeloperoxidase activation
- Reducing proinflammatory cytokines
- Ameliorating oxidative damage 4
Clinical Application
When to Consider Using Arnica
- For minor bruising following:
- Cosmetic procedures
- Minor trauma
- Laser treatments
How to Use
- Topical application:
- 20% arnica ointment appears to be more effective than lower concentrations 1
- Apply twice daily to affected area
- Can be used under occlusion for potentially better results
Important Considerations
- The Society for Perioperative Assessment and Quality Improvement (SPAQI) recommends that oral arnica supplements should ideally be held for 2 weeks before surgery due to potential bleeding risk 5
- Arnica is classified as a supplement that may affect bleeding risk, along with other herbs like ginkgo, garlic, and ginger 5
Limitations and Caveats
- Quality of evidence is generally low to moderate
- European League Against Rheumatism (EULAR) guidelines note that safety information for homeopathic arnica is limited, as adverse events were not reported in many trials 5
- First aid guidelines for bruising recommend localized cold therapy with or without pressure for hemostasis in closed bleeding in extremities, but do not specifically mention arnica 5
Alternative Approaches for Bruising
- Localized cold therapy with or without pressure is recommended for hemostasis in closed bleeding (weak recommendation, very-low-quality evidence) 5
- Proper documentation of bruises should include precise anatomical location, size and shape measurements, color and appearance, and pattern characteristics 6
For patients seeking treatment for bruising, topical 20% arnica may be tried as an adjunctive therapy, but patients should be informed about the limited and conflicting evidence regarding its effectiveness.