New: A treatment designed for rosacea-prone skin

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Dangers arnica.

Are there any contraindications to using arnica macerate?

Applied to the skin in the form of cream, ointment, gel, mist, or balm, arnica remains as popular as ever. It is particularly recommended for relieving joint and muscle pain, calming inflammatory reactions, and healing wounds. Increasingly used, it is often declared as safe and harmless. But does arnica truly not cause any adverse effects after a topical application?

What do we know about the safety of arnica used in cosmetic formulations?

Topicallyadministered arnica is generally well-tolerated and suitable for all skin types. During patch tests in vivo on the skin of rabbits, mice, and rats, and in clinical trials, arnica extract has proven to be non-irritating, non-sensitizing, and non-phototoxic at various concentrations and over short-term use. However, clinical trials have reported contact allergic dermatitis, or a delayed type IV hypersensitivity reaction, in some subjects, caused by sesquiterpene lactones. Redness, itching, dry skin... if any of these side effects occur during the topical application of arnica, immediately stop using the product and consult a doctor.

  • Case No. 1 : In a clinical study involving 443 patients, five subjects (1.1%) showed positive reactions to patch tests with arnica. They were referred for eczematous allergic reactions of the hands or face, resulting in itching and dry skin.

  • Case No. 2 : In a study by SUTER A. & al, six allergic reactions out of 79 subjects (7.6%) occurred after a topical application of an arnica gel, twice a day for three to six weeks, for the treatment of mild to moderate knee osteoarthritis. These were primarily mild to moderate local reactions at the application site, namely an allergy accompanied by redness, itching, skin dryness, an episode of pruritus, an increase in pain, and a localized skin rash.

  • Case No. 3 : MELZER J. & al. reported in their double-blind randomized study that adverse effects (itching, irritation, redness) occurred in 5 out of 105 patients (4.8%) receiving topical arnica gel for the treatment of hand osteoarthritis, after 21 days of application.

Further trials involving larger cohorts of patients are necessary to evaluate the safety of using arnica on the skin and the appropriate dosages.

Although it is of natural origin, like any active ingredient applied to the skin, there is always a risk that the skin may react to arnica and develop erythema. Furthermore, being part of the sunflower family and related plants (Asteraceae), individuals allergic to flowering plants of this family should ensure to discuss it with a healthcare professional before considering applying any arnica-based skincare on the skin.

Pregnant Women and Young Children: Can They Safely Use Arnica?

It is generally suggested that topical products containing arnica can be safely used during pregnancy and breastfeeding. However, there is limited data available regarding the safety of using arnica topically in children, pregnant women, and breastfeeding mothers. One study documented a case of hemolytic anemia and an increase in bilirubin in a nine-day-old breastfed infant, which developed 48 hours after the mother consumed a tea made from arnica flowers. Although this was a case following oral ingestion of botanical products containing arnica, extra caution is still required for these groups and it is advised to seek your doctor's opinion.

When taken orally, arnica can cause serious side effects (dizziness, tremors, gastroenteritis, dry mouth, tachycardia, vomiting, diarrhea, lethargy and death). It can also cause irritations in the mucous membranes and vomiting. It is safe and well tolerated only at very low concentrations, such as those used in homeopathic medicines. Therefore, any internal use should be closely monitored by a medical professional.

Precautions to take when using topical arnica extract?

Even though arnica is generally harmless for most people when used according to the manufacturer's application instructions for topical use, here are some tips for using arnica safely and effectively in skincare.

  • patch test on a small area of the skin before applying a new arnica-based product to ensure there will be no side effects;

  • Follow the instructions on the arnica-based product label, particularly regarding the amount to use and the frequency of application ;

  • Do not apply arnica to an open wound or damaged skin, as there is a risk that a large amount of arnica may be absorbed, potentially leading to systemic side effects;

  • Start with a treatment that has a lower concentration of arnica or contains soothing ingredients in its formula, especially if you have sensitive and atopic skin;

  • Do not apply arnica to the eyes, mouth, and private areas.

Sources

  • Final report on the safety assessment of Arnica montana extract and Arnica montana. International Journal of Toxicology (2001).

  • ABERER W. & al. The seamy side of natural medicines: contact sensitisation to arnica (Arnica montana L.) and marigold (Calendula officinalis L.). Contact Dermatitis (2001).

  • SUTER A. & al. Arnica montana gel in osteoarthritis of the knee: an open, multicenter clinical trial. Advances in Therapy (2002).

  • MELZER J. & al. Choosing between NSAID and arnica for topical treatment of hand osteoarthritis in a randomised, double-blind study. Rheumatology International (2007).

  • CLARK R. F. & al. Neonatal hemolysis associated with nursing mother ingestion of arnica tea. Clinical Toxicology (2009).

  • HLADIKOVÁ M. & al. Arnica/Hydroxyethyl salicylate combination spray for ankle distortion: a fourarm randomised double-blind study. Pain Research and Treatment (2011).

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