What should we know about nettle?

The nettle belongs to the Urticaceae family and is part of the botanical genus Urtica, which encompasses numerous different species of nettles. However, they all share a common ability to sting. Indeed, upon contact with the skin, their leaves trigger an inflammatory reaction on the skin's surface. However, some species prove beneficial for the body, skin, and hair. These include the stinging nettle, or Urtica dioica, and the small nettle, or Urtica urens.

• Urtica dioica.

  This refers to a herbaceous plant perennial, meaning it can live for several years. It thrives in temperate regions and primarily grows on rich soils. The stinging nettle measures between 50 cm and 1 m in height. Its leaves have a dark green colour, almost black on the top and are lighter underneath. As for its roots, they are creeping and develop rhizomes.

• Urtica urens.

  The burning nettle distinguishes itself from the dioecious nettle by its smaller size, approximately 40 cm. Furthermore, it is an annual plant, not a perennial. The burning nettle can thrive in uncultivated areas such as meadows or forests. Its leaves are lighter on the top. Unlike the common nettle, the burning nettle has tap roots and does not possess rhizomes.

It is possible to obtain an extract rich in molecules beneficial for the skin and hair from the leaves of the nettle. The table below summarises the various active ingredients found in the nettle extract, as well as the main properties associated with them. Percentages are not indicated as these vary depending on the variety of nettle and the extraction method used.

When applied topically or to the hair, nettle has numerous benefits.

• Purifying.

  Thenettle extract is a favoured ingredient among individuals with oily skin. The benefits of nettle for this skin type can be attributed to its ability to inhibit 5-α-reductase, the enzyme that catalyses the conversion of testosterone into dihydrotestosterone (DHT). When DHT binds to a cytosolic receptor in the sebaceous glands, it intensifies sebum production. By inhibiting this process, nettle helps to regulate oily skin.

• Anti-inflammatory and soothing.

  Studies have shown that nettle acts at various levels to reduce inflammation. One can particularly think of its inhibitory effect on 5-lipoxygenase, an enzyme involved in the metabolism of arachidonic acid. This latter increases the production of cyclooxygenases COX-1 and COX-2, molecules that catalyse the formation of prostaglandins. Prostaglandins are the pro-inflammatory compounds responsible for redness and itching, particularly observed in cases ofeczema.

• Antibacterial.

  The nettle extract also contributes to the regulation of microorganism populations living on our skin. It particularly has a inhibitory effect on the growth of Cutibacterium acnes, the bacteria associated with acne. The nettle extract can thus be used to reduce blemishes.

• Antioxidant.

  Nettle extract contains several antioxidant molecules which, through an electron donation, are capable of neutralising free radicals before they can damage cells and DNA. It's worth noting that free radicals are particularly generated following exposure to UV rays, pollution, tobacco... and can lead to pigmentation disorders, melanomas or premature skin ageing.

• Prevention of skin ageing.

  In addition to its antioxidant properties, nettle extract has a collagenase and elastase inhibitory effect. These are enzymes that degrade collagen and elastin, fibres in the dermis that ensure skin flexibility and elasticity. Thus, nettle extract helps to delay skin sagging.

• Anti-dandruff.

  It has also been demonstrated that nettle extract can help to eliminate dandruff. Dandruff is multifactorial and can particularly result from hyperseborrhea or colonisation by the fungus Malassezia. In addition to being sebum-regulating, nettle extract has antifungal activity against these parasites. It is therefore often included in the composition of anti-dandruff shampoos.

• Prevention of hair loss.

  Finally, studies have highlighted that nettle extract is capable of preventing hair loss. This property is explained by its inhibitory action on 5-α-reductase, the enzyme responsible for the conversion of testosterone into dihydrotestosterone (DHT). DHT intensifies the activity of interleukin-6 (IL-6), cytokines that accelerate the transition between the growth and rest phases of hair. Thus, DHT more rapidly induces hair follicles into the telogen phase, or hair shedding phase. By inhibiting 5-α-reductase, nettle thus protects hair from hormonal fluctuations or genetic predispositions leading to an increased production of DHT and consequently to hair loss.

Unlike the nettle leaf, thenettle extract found in cosmetic care is a ingredient that does not cause irritation. It can be used by the whole family, including pregnant women and children over three years old. However, nettle extract can be somewhat drying depending on the individual. This adverse effect is far from systematic but is occasionally observed. It also depends on the other ingredients present in the care formula. Moreover, some people may be allergic to nettle extract. Applying this ingredient to their skin causes temporary redness and itching.

That's why we recommend you to carry out a tolerance test before applying a skincare product containing nettle extract if you have never used it before. This will allow you to ensure that your skin is not allergic to this ingredient. 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 means your skin tolerates nettle well.

At Typology, we have formulated a purifying mask based on nettle extract, green clay and pine charcoal, active ingredients that are appreciated by oily skin types. Composed of 99% natural origin ingredients, this treatment dries out imperfections and tightens pores for healthier skin. Its clay-like texture leaves the skin soft and comfortable. Our mask should be applied once or twice a week on cleansed skin and left on the face for about fifteen minutes before rinsing.

• HANO C. & al. Nettle (Urtica dioica L.) as a source of antioxidant and anti-aging phytochemicals for cosmetic applications. Comptes-Rendus Chimie (2016).

• SEMALTY A. & al. A Comprehensive Review on Phytochemistry and Pharmacological Effects of Stinging Nettle (Urtica dioica). Current traditional medicine (2017).

• KILIC S. & al. Efficacy of two plant extracts against acne vulgaris: Initial results of microbiological tests and cell culture studies. Journal of cosmetic dermatology (2018).

• TURKOGLU M. & al. A proprietary herbal extract against hair loss in androgenetic alopecia and telogen effluvium: a placebo-controlled, single-blind, clinicalinstrumental study. Acta Dermatovenerologica (2018).