Nettle: What are the adverse effects of topical application?

The nettle is a plant that thrives in temperate climates. It is characterised by stinging leaves that cause inflammatory reactions on the skin's surface. The nettle belongs to the Urticaceae family, which encompasses numerous species. Two of these are sometimes incorporated into cosmetic care, namely Urtica dioica, or stinging nettle, and Urtica urens, or dwarf nettle. Nettles have been used as medicinal and cosmetic ingredients since antiquity. The Egyptians notably used them to enhance the growth of their hair and make it shinier.

Thenettle also brings a host of benefits to the skin. Sebum-regulating, it is the ally of oily skin and helps to combat excess sebum. Added to this are antibacterial properties against Cutibacterium acnes and anti-inflammatory properties, making the nettle an ideal ingredient for alleviatingacne. It is also worth noting that it is capable of inhibiting the activity of collagenase and elastase, two enzymes involved in skin ageing. Finally, nettle has antioxidant properties thanks to the polyphenols it contains. It can thus protect the skin from free radicals, molecules notably generated in the body after UV exposure and causing several skin disorders (hyperpigmentation, skin sagging, melanomas...).

Unlike the nettle leaf, the nettle extract found in cosmetic products is a ingredient that does not cause irritation. Its concentration is not subject to any restrictions by European cosmetic regulations, which are based on Regulation (EC) No 1223/2009. This regulation establishes the requirements applicable to cosmetic products, thus providing a regulatory framework for their marketing. This includes measures such as product notification on the market, maintaining a product safety information file, and concentration restrictions when incorporating an active ingredient into a formula.

Nevertheless, nettle is generally used at rates ranging between 2 and 10% in cosmetic care, a higher concentration does not bring additional benefits. Moreover, this ingredient can be used by the whole family, including children over three years old. It is also not discouraged for pregnant and/or breastfeeding women.

However, it should be noted that the topical application of a skincare product containing nettle extract can sometimes result in mild skin dryness. This adverse effect is far from being systematic but is occasionally observed. It also depends on the other ingredients present in the skincare formula. Moreover, there are instances where some individuals are allergic to nettle extract. Applying this ingredient to their skin causes temporary redness and itching.

If you have just purchased a skincare product containing nettle extract, it is advisable to take some precautions before enjoying its benefits. We first recommend conducting a tolerance test, to ensure that the use of this ingredient does not cause redness, itching, or allergies on your skin. To do this, apply a small amount of the product to a small area of your face, the inside of your elbow or behind your ear. If you do not notice any adverse reaction within the following 24 hours, it indicates that your skin tolerates the nettle well.

• Règlement (CE) No 1223/2009 du Parlement Européen et du Conseil.

• BENMOUSSA A. & al. Mise en valeur du potentiel nutritionnel et thérapeutique de l’ortie dioïque (Urtica dioïca L.). Hegel (2016).