Ingredient Beauty BenefitsSoothing · Arnica Montana Flower Extract
Arnica: 20% ointment beat petrolatum — and that is usually not the strength on the shelf
In a trial scored by a blinded rater, 20% arnica ointment resolved bruises better than white petrolatum (P = 0.003). In the same trial it was better than 1% vitamin K with retinol (P = 0.01) and not better than 5% vitamin K. But 20% is not a common strength on the shelf, and homeopathically diluted products are not the same thing as what was tested.
Last checked Sep 28, 2026
Start here
- What it is
An extract from the flowers of a daisy-family plant of European mountains. Applied as an ointment or gel.
- What it is used for
Long sold as something to apply to bruises and knocks.
- How it is said to work
It is said to contain compounds acting on inflammation and to help a bruise clear faster.
There are no numbers and no citations in this box. What has been established, and how far, is below.
At a glance
- In pregnancy
- Not established
- Irritation
- Low
- Daytime use
- ✓ Fine
- How well established
- Early research
- Concentration studied
- Not disclosed
- Length of the studies
- 2 weeks
Not a measurement — reported irritation grouped into five steps. It varies between people.
“Concentration studied” and “Length of the studies” are taken straight from the research on this page. They are not a recommended dose, and the figure for each finding is written out in the text.
This is not how large the effect is but how well confirmed it is. It shows the highest grade among the findings on this page.
Arnica is a daisy-family plant of European mountains. An extract of its flowers is made into an ointment or gel and applied to bruises and knocks. It has been sold for a long time.
The most important number on this page is not an effect size but a strength — 20%.
What the trial below used is a 20% arnica ointment. But two different things are sold as 'arnica'.
- an ointment or gel containing the extract at some stated strength — what the trial looked at. Though many products do not state the percentage.
- a homeopathic dilution — the ones labelled things like 30C. That is not what the trial looked at. Same name on the tube, a different amount inside.
This site does not estimate concentrations it has not read, so the concentration field on the badge below is empty. If a product does not state one, the result below cannot be carried across to it.
And the trial below is the same trial as on the vitamin K page. One trial compared four agents at once. Do not count the two pages' badges separately.
The reason no concern is attached is the same too. Bruising is not on this site's list of concerns. It is not a concern but recovery after a procedure, and it is linked from procedure pages like vascular laser and filler.
What is established
The same ingredient at a different strength, in a different formula, is a different product. These are the conditions the studies used.
A 20% ointment beat white petrolatum
A 2010 trial at Northwestern University. It is the same trial as on the vitamin K page.
The design is among the better ones on this site.
Healthy volunteers aged 21 to 65 were enrolled, and four standard bruises 7 mm across were created with a 595 nm pulsed dye laser on the inner upper arms (two per arm, 5 cm apart). Each of a person's four bruises was then randomly assigned one of four agents.
- 20% arnica
- 5% vitamin K
- 1% vitamin K with 0.3% retinol
- white petrolatum (control)
Twice daily under occlusion for two weeks. A dermatologist not involved in assignment scored standardised photographs on a 0 (least) to 10 (most) scale immediately after the bruises were made and at week two. Both patient and rater were blinded.
The results.
- there was a significant difference in the change in bruising score across the four treatments (anova, P = 0.016)
- 20% arnica > white petrolatum (P = 0.003)
- 20% arnica > 1% vitamin K with 0.3% retinol (P = 0.01)
- 20% arnica > 5% vitamin K was not the case (no difference found)
Now how to read it.
First, the design is good. Four agents compared at once within the same person (own control), both patient and rater blinded, and a third doctor scoring standardised photographs. The problem this site keeps pointing at — the person who did the treatment rating the result — is absent here.
Second, and it beat placebo. P = 0.003 against white petrolatum. That is not a result you see often on the ingredient pages here.
Third, the abstract does not give the number of participants. Each person had four bruises, so there were more bruises than people, but how many people there were is not in the abstract. We will not invent it. That is why the participant field on the badge above is empty.
Fourth, these were standard bruises made deliberately with a laser. 7 mm across, same device, same site. They cannot be assumed to be the same as a bruise that actually follows a procedure, or one from a knock. Real bruises differ in depth, size and place.
Fifth, the paper's own conclusion is hedged. It says 20% arnica ointment may be able to reduce bruising more than placebo and more than low-concentration vitamin K formulations. That is the strength of conclusion one trial can carry.
Sixth, the strength again. This trial is 20%. You cannot assume a product on the shelf is that.
So it sits at 'early evidence'. The design is among the better ones here, but there is one trial, the abstract omits the participant count, and the bruises were made to order.
- Randomised controlled trial in people · sample size not reported · 2 weeks · Compared with vehicle (same formula minus the active) · Funding not declared · Endpoint scores from blinded assessors PMID 20412090
How to use it
- The trial used a 20% ointment, twice daily under occlusion for two weeks. This site does not estimate concentrations it has not read.
- If a product does not state a strength, the result above cannot be carried across to it. Especially not to homeopathic dilutions (labelled 30C and the like) — that is not what was tested.
- Arnica taken by mouth is not this page's subject. This page is about topical forms.
- Do not apply it to open wounds. Immediately after a procedure, follow the instructions from where it was done.
- Compare it with vitamin K, used in the same place. The trial above compared the two head to head.
- Note that the control was petrolatum. Petrolatum carries 'strong evidence' on this site — but for other uses, not for bruising.
Cautions
- It is a daisy-family plant. If you have reacted to chrysanthemum, mugwort or daisies, contact dermatitis is possible. Test a small area first.
- Contact dermatitis to arnica has been reported. This applies especially before applying it widely.
- Do not apply it to open wounds, mucous membranes or gaping suture lines.
- Keep oral and topical apart. Swallowed forms are not covered on this page.
- We found no data on use in pregnancy or breastfeeding.
- If your bruises are unusually large, last unusually long, or appear repeatedly and easily, establish the cause in a clinic before picking something to apply.
With a new ingredient, apply a small amount somewhere inconspicuous, such as the inner arm, for two days first. Stop if it reddens or stings.
What this article relies on
- PubMed — 미국 국립의학도서관 문헌 데이터베이스National Library of Medicine · Checked on 2026-09-16