Are there any contraindications regarding the use of lemon verbena on the skin?

Thelemon verbena hydrosol (INCI: Lippia Citriodora Leaf Water) is obtained through hydrodistillation of the plant's flowers. It presents itself as a colourless liquid, with a characteristic lemony scent. Lemon verbena floral water is found in numerous skin and hair care products due to its various virtues.

• Antioxidant properties.

  UV rays, pollution, stress... these are all factors that contribute to the production of free radicals. Once generated, these attack DNA and cells, promoting skin ageing, skin dullness, and the appearance of white hair. Lemon verbena hydrosol, being an ingredient rich in antioxidants, its topical application aids the skin and scalp in eliminating them.

• Anti-inflammatory effects.

  Lemon verbena hydrosol can be utilised to alleviate redness or itching, on the skin or the scalp. It contains several molecules with anti-inflammatory properties, such as geranial, capable of inhibiting the activity of NLRP3, an inflammasome complex that triggers the synthesis of pro-inflammatory cytokines. Thus, lemon verbena floral water has a soothing effect on mild discomfort.

• Antimicrobial activity.

  The hydrosol of lemon verbena has the ability to inhibit the capacity of certain bacteria to communicate with each other via molecular mediators (quorum sensing). Among these bacteria, we find Cutibacterium acnes, which is partly responsible for acne. Thus, the floral water of lemon verbena is highly appreciated by individuals prone to blemishes.

• "Purifying" properties?

  It is sometimes suggested that lemon verbena hydrosol has the ability to reduce the overproduction of sebum by the sebaceous glands, which is responsible for shiny skin and greasy hair, due to the linalool it contains. However, no scientific study on this botanical extract has so far been able to demonstrate this property. Furthermore, the concentration of linalool in lemon verbena floral water is very low (≈ 1%) and may be insufficient to induce such an effect.

• A tightening effect and anti-stretch mark?

  Some sources suggest that lemon verbena hydrosol may have effects on purple stretch marks and skin sagging. However, to date, no scientific study has demonstrated that the topical application of lemon verbena hydrosol has any impact on these issues.

The application of lemon hydrosol is suitable for all skin types, particularly combination to oily or irritated skin, and this ingredient is suitable for sensitive skin. Moreover, it presents no danger when used topically by pregnant women and young children. However, be sure to not use pure lemon verbena floral water. It is often diluted in water, typically at a concentration between 5 and 10%.

Furthermore, lemon verbena hydrosol is an ingredient that is mildly photosensitising, meaning it increases the skin's sensitivity to UV rays. This is due to the traces of furocoumarins that some hydrosols contain, compounds that induce type I photosensitisation. Furocoumarins absorb the sun's light rays and react through fluorescence, that is, they re-emit the absorbed energy. However, when they are applied to the skin, the energy they emit is directly transmitted to the oxygen atoms present in the epidermis, which then become free radicals capable of damaging cellular components.

Thus, the application of certain lemon verbena hydrosols requires precautions and must be accompanied by the use of a broad-spectrum sunscreen. As for the lemon verbena hydrosol present in Typology skincare products, it contains no furocoumarins and is not photosensitising.

• CANAC P. & al. Traité d'aromathérapie scientifique et médicale, les hydrolats (1ère édition). Paris : Édition Sang de la Terre (2018).