Reunoa side effects and safety — what to know before you start
By Margaret Hale, Reunoa EditorialLast updated
The short answer
Reunoa Bruise Defense & Repair Serum is a topical cosmetic, and most people use it without problems. Possible side effects are those of any skincare: redness, itching or rash, most often in people allergic to arnica or other daisy-family plants. Don't apply it to broken skin. It acts on the skin, not in the blood, so blood thinners stay exactly as prescribed. Reunoa is not Renova (tretinoin).
Key takeaways
- The most likely side effect is skin irritation or an allergic rash — patch-test first if you have sensitive skin.
- People allergic to daisy-family plants (ragweed, chamomile, chrysanthemum, marigold) are more likely to react to arnica [1].
- Don't use on open wounds, skin tears or broken skin.
- Reunoa is a cosmetic applied to skin; it does not change how your blood clots. Keep all medicines as prescribed.
- Searching "Reunoa side effects" sometimes brings up Renova — a prescription tretinoin cream. That's a different product.
On this page
Before putting anything new on fragile skin, it's sensible to ask what could go wrong. Here are honest answers from Reunoa — including who should not use our serum.
Is Reunoa safe?
Reunoa Bruise Defense & Repair Serum is a cosmetic for external use on intact skin [4]. It's fragrance-free, paraben-free and hormone-free [6], and it's designed for daily long-term use on mature skin. Most people use it without any problems.
But no skincare product is right for everyone. Any product with plant extracts can cause irritation or an allergy in a small number of people.
Possible side effects
| Reaction | What it looks like | What to do |
|---|---|---|
| Mild irritation | Slight stinging or warmth for a few minutes after applying, especially on very dry skin | Usually settles; use less product, apply to dry (not freshly washed) skin |
| Redness or itching | Pink, itchy skin where you applied it | Stop for a few days; if it returns when you restart, stop using it |
| Allergic contact dermatitis | Itchy rash, bumps, blistering or swelling, sometimes a day or two after use | Stop using it, wash the area, and talk to a pharmacist or doctor |
| Dryness | Tight feeling | Follow with a plain moisturiser |
Allergic reactions to topical arnica are documented in medical literature, mostly with strong tinctures and repeated use [2]. Rare contact allergies have also been reported with cosmetic vitamin K [3].
Who should not use Reunoa (or should ask first)
- People allergic to arnica or the daisy (Compositae/Asteraceae) family — including ragweed, chamomile, chrysanthemum, sunflower, marigold and echinacea. The allergens in this plant family can cross-react [1].
- Anyone with open wounds, skin tears, ulcers or broken skin on the area — wait until it has healed.
- Anyone with a skin condition under treatment (for example eczema, psoriasis or a skin infection) — ask your doctor first.
- People who are pregnant or breastfeeding — ask your doctor before using arnica products.
- Children — Reunoa is made for adults.
How to patch-test
- Apply a small amount to a coin-sized area on the inside of your forearm.
- Leave it for 24–48 hours without washing it off.
- If there's no redness, itching or rash, you can start using it as directed.
- If you react, don't use it.
Reunoa and blood thinners
This is the most common question we get. Reunoa is applied to the skin, where it works on the skin. It isn't swallowed and it doesn't act in your bloodstream. Keep taking your blood thinner — and every other medicine — exactly as prescribed [7].
People on warfarin are asked to keep their vitamin K intake from food steady, because warfarin works by blocking vitamin K [5]. Vitamin K applied to skin in a cosmetic is a different route, but as a simple precaution, mention any new vitamin K–containing skin product to your anticoagulation clinic and keep your regular INR checks. Apixaban (Eliquis), rivaroxaban (Xarelto) and dabigatran don't work through vitamin K.
Read more: bruising on blood thinners.
Reunoa is not Renova
If you've searched "Reunoa side effects", you may have seen results about Renova — a prescription tretinoin cream for wrinkles and sun damage, with side effects such as peeling and sun sensitivity. Reunoa is a completely different product, with no tretinoin or other prescription ingredients.
When to stop and get advice
Stop using any skincare product and talk to a pharmacist or doctor if you get a spreading rash, blisters, swelling or itching that doesn't settle. Seek urgent care for swelling of the face, lips or tongue or difficulty breathing. You can also email support@reunoa.com — we log every reaction we hear about.
Frequently asked questions
Does Reunoa have side effects?
Most people use Reunoa without problems. Possible side effects are the same as with other skincare: mild stinging, redness, itching or, rarely, an allergic rash — most likely in people allergic to arnica or daisy-family plants. Stop using it if your skin reacts.
Is Reunoa safe with blood thinners?
Reunoa is a cosmetic applied to the skin; it doesn't act in the blood. Keep taking your blood thinner as prescribed. If you take warfarin, tell your anticoagulation clinic about any new vitamin K–containing skin product as a precaution.
Can I use Reunoa if I'm allergic to ragweed?
Ragweed belongs to the same plant family as arnica, and cross-reactions are possible. Ask your doctor or pharmacist first, and do a patch test on a small area for 48 hours before using it more widely.
Can I put Reunoa on a skin tear or open cut?
No. Apply Reunoa only to intact skin. Let skin tears and cuts heal first, and follow your nurse's or doctor's advice on dressings.
Is Reunoa the same as Renova?
No. Renova is a prescription tretinoin cream. Reunoa is a cosmetic serum with arnica, vitamin K and ceramides and contains no tretinoin.
Sources
- Gordon LA Compositae dermatitis. Australasian Journal of Dermatology, 1999. PubMed 10439521
- Hörmann HP, Korting HC Allergic acute contact dermatitis due to Arnica tincture self-medication. Phytomedicine, 1995. PubMed 23196021
- Veneziano L, et al. Contact dermatitis due to topical cosmetic use of vitamin K. Contact Dermatitis, 2005. PubMed 15725297
- Is It a Cosmetic, a Drug, or Both? (Or Is It Soap?) — U.S. Food and Drug Administration.
- Warfarin — Drug Information — MedlinePlus.
- Reunoa — official store (product information, FAQ, guarantee) — reunoa.com.
- Blood Thinners — MedlinePlus (U.S. National Library of Medicine).
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.