What's in Reunoa? The ingredients, what they do and the research behind them
By Margaret Hale, Reunoa EditorialLast updated
The short answer
Reunoa Bruise Defense & Repair Serum is built on three key actives — Arnica montana at 15%, vitamin K and ceramides — plus deep hydrators and repair boosters such as vitamin C (sodium ascorbyl phosphate) and niacinamide. It is fragrance-free, paraben-free and hormone-free. Arnica and vitamin K have been studied for bruising; ceramides support the skin barrier.
Key takeaways
- 15% Arnica montana — a high, clearly stated concentration; many drugstore arnica products are homeopathic. 20% arnica ointment sped bruise fading versus placebo in a randomised trial [2].
- Vitamin K — reduced bruise severity after laser treatment in a controlled study [4].
- Ceramides — barrier lipids; topical physiological lipids improved barrier function in a recent trial [6].
- Vitamin C and niacinamide — support collagen and barrier function; vitamin C is essential for collagen [8].
- Studies tested ingredients, not Reunoa itself. Always check the label on your bottle for the full ingredient list.
On this page
Fragile skin has three structural problems: the skin is thinner, the tiny vessels under it break easily, and leaked blood clears slowly. Reunoa's formula assigns an ingredient to each one [1].
The three core actives
| Ingredient | Role in the formula | What published research shows |
|---|---|---|
| Arnica montana, 15% | Helps the look of bruises fade faster | 20% arnica ointment improved laser-induced bruises more than placebo [2]; homeopathic arnica didn't beat placebo after eyelid surgery [3] |
| Vitamin K | Supports the look of fragile capillaries and discoloration | Vitamin K cream after laser treatment reduced bruise severity [4]; vitamin K + retinol sped resolution [5] |
| Ceramides | Replenish the skin barrier so skin feels more "padded" and less fragile | Topical physiological lipids improved barrier strength in a 2025 trial [6]; ceramides are key barrier lipids [7] |
Arnica montana at 15%
Arnica is a yellow mountain flower used on bruises for centuries. The key word is concentration. Many drugstore arnica gels are homeopathic, which means they're diluted to tiny amounts. In a randomised trial, homeopathic arnica showed no benefit for bruising after eyelid surgery [3], while a 20% arnica ointment helped bruises improve significantly more than placebo [2]. Reunoa states its arnica concentration on the label: 15%. Strengths aren't always comparable between brands — homeopathic labels use dilution codes such as "1X" instead — so look for products that tell you how much arnica they contain.
Vitamin K
Vitamin K is central to normal clotting. Applied to the skin, vitamin K cream reduced bruise severity after laser treatment when used afterwards [4], and a vitamin K–retinol cream sped the clearing of laser bruises [5]. These are small studies on procedure-related bruises, so they're encouraging rather than conclusive.
Ceramides
Ceramides make up a large part of the "mortar" between skin cells in the outer layer. They help keep moisture in and irritants out [7]. A 2025 study in adults with eczema-prone skin found that applying physiological skin lipids to the forearms and lower legs rebalanced the skin's ceramide profile and strengthened its barrier [6]. For thin skin, a stronger barrier means skin that feels more supple and resilient.
Supporting ingredients
- Deep hydrators — help skin hold water so it feels softer and less tight.
- Vitamin C (sodium ascorbyl phosphate) — a stable form of vitamin C. The body needs vitamin C to make collagen [8].
- Niacinamide (vitamin B3) — supports the barrier and evens the look of skin tone.
What Reunoa leaves out
- No fragrance, parabens or hormones [1] — fewer common irritants for sensitive skin.
- No retinol or acids — these can help aged skin but often sting or peel very thin skin. Some purpura creams include them [9]; see our Reunoa vs DerMend comparison.
Allergy note
Arnica belongs to the daisy family (Asteraceae/Compositae). People allergic to ragweed, chamomile, chrysanthemums or marigolds may react to it [10]. Do a patch test first if you have sensitive skin. See side effects and safety.
Is it a drug?
No. Reunoa is a cosmetic serum. It works on the skin, not in the blood, and it doesn't replace any medicine you've been prescribed.
Frequently asked questions
What are the main ingredients in Reunoa?
The core actives are Arnica montana at 15%, vitamin K and ceramides, supported by deep hydrators, vitamin C (sodium ascorbyl phosphate) and niacinamide. The serum is fragrance-free, paraben-free and hormone-free.
How much arnica is in Reunoa?
Reunoa contains 15% Arnica montana. That's a high, clearly stated concentration; many drugstore arnica products are homeopathic and list a dilution code instead of a percentage of extract.
Does Reunoa contain retinol?
No. Reunoa doesn't contain retinol or exfoliating acids, which can irritate very thin, fragile skin. It focuses on arnica, vitamin K and barrier-repairing ceramides.
Is Reunoa natural?
Reunoa combines plant-derived ingredients such as arnica with skin-identical ingredients such as ceramides and vitamins. It's free from fragrance, parabens and hormones. "Natural" doesn't automatically mean allergy-free, so patch-test if your skin is sensitive.
Where can I see the full ingredient list?
The full ingredient list is printed on the bottle and its packaging. If you need it before ordering, email support@reunoa.com.
Sources
- Reunoa — official store (product information, FAQ, guarantee) — reunoa.com.
- Leu S, et al. Accelerated resolution of laser-induced bruising with topical 20% arnica: a rater-blinded randomized controlled trial. British Journal of Dermatology, 2010. PubMed 20412090
- Kotlus BS, et al. Evaluation of homeopathic Arnica montana for ecchymosis after upper blepharoplasty: a placebo-controlled, randomized, double-blind study. Ophthalmic Plastic and Reconstructive Surgery, 2010. PubMed 20683279
- Shah NS, et al. The effects of topical vitamin K on bruising after laser treatment. Journal of the American Academy of Dermatology, 2002. PubMed 12140470
- Lou WW, et al. Effects of topical vitamin K and retinol on laser-induced purpura on nonlesional skin. Dermatologic Surgery, 1999. PubMed 10594627
- Andrew PV, et al. Topical supplementation with physiological lipids rebalances the stratum corneum ceramide profile and strengthens skin barrier function. British Journal of Dermatology, 2025. PubMed 40408261
- Yong TL, et al. Ceramides and Skin Health: New Insights. Experimental Dermatology, 2025. PubMed 39912256
- Vitamin C — MedlinePlus Medical Encyclopedia.
- Ceilley RI Treatment of Actinic Purpura. Journal of Clinical and Aesthetic Dermatology, 2017. PubMed 28979656
- Gordon LA Compositae dermatitis. Australasian Journal of Dermatology, 1999. PubMed 10439521
General information, not medical advice. Written by the Reunoa editorial team; Reunoa makes Bruise Defense & Repair Serum. See our editorial policy for how we pick sources and keep product mentions fair.