Lemon Verbena Hydrosol: What are its benefits for hair?

The lemon verbena is a perennial shrub plant from the Verbenaceae family. It has a pleasant and fresh scent and is often used in perfumery. Mainly cultivated in the tropical regions of South America, such as Argentina, Peru, and Chile, it was considered a sacred flower during antiquity. The Egyptians named it "tears of Isis," as it is said to have grown from the tears shed by the funerary goddess Isis upon learning of the death of her husband Osiris.

Thelemon verbena hydrosol is extracted from the flowering tops through hydrodistillation. This technique yields a colorless, slightly opalescent liquid with a lemony scent similar to that of the plant. Although the floral water is less concentrated in active ingredients than its essential oil, it remains an interesting ingredient to incorporate into cosmetic care. Moreover, it can be used by pregnant or breastfeeding women. It should be noted that lemon verbena hydrosol is never applied pure, but mixed with water or a vegetable oil. It is generally recommended to dilute it to 5 to 10%.

The application of lemon verbena floral water can reduce scalp irritations and discomfort. Indeed, it contains several molecules with anti-inflammatory properties. Lemon verbena hydrosol is particularly rich in geranial. A study has shown that this molecule inhibits the activity of NLRP3, a inflammasome complex that triggers an inflammatory signaling pathway. It notably increases the synthesis of interleukin-1 (IL-1) and interleukin-4 (IL-4), pro-inflammatory cytokines.

Furthermore, linalool is found in the composition of lemon verbena floral water, a terpenic alcohol that promotes the synthesis of HSP70 proteins (Heat Shock Protein). These proteins ensure the proper conformation of proteins found in the body's cells and help them protect against external stressors (heat, heavy metals...), which could potentially cause inflammatory responses. Thus, applying lemon verbena hydrosol to the scalp can alleviate itching, which also reduces flaking.

The lemon verbena hydrosol is sometimes attributed with anti-parasitic properties, similar to those of the true lavender essential oil, due to the linalool it contains. Indeed, this molecule inhibits acetylcholinesterase, an enzyme found in these parasites that leads to the degradation of their acetylcholine neurotransmitter. This mechanism is the basis of the neurotoxicity presumed of the lemon verbena hydrosol for lice. However, it should be noted that linalool only represents 1% of the composition of the lemon verbena floral water, compared to about 35% of that of lavender essential oil. Moreover, no study has directly demonstrated the anti-parasitic properties of the lemon verbena hydrosol. Therefore, caution should be exercised on this matter.

According to some sources, lemon verbena floral water is said to have matifying and "purifying" properties, and it could help reduce the overproduction of sebum by the sebaceous glands, which is the cause of oily hair. Indeed, it seems that the linalool present in its composition has a sebum-absorbing effect.

However, no scientific study focusing on lemon verbena hydrosol itself has so far demonstrated this property. Therefore, we cannot assert that the application of this extract has a genuine "purifying" action. Furthermore, the concentration of linalool in lemon verbena floral water is very low and may be insufficient to induce such an effect.

Applying lemon verbena hydrosol to the hair fiber could potentially slow down the graying of hair. This assumption is due to the presence of citral in its composition, accounting for almost 50%. Citral is a recognized antioxidant, capable of combating free radicals, reactive species that can weaken the hair bulb, and promote hair loss and split ends. Its application to the hair thus helps to protect the hair from certain aggressions such as exposure to UV radiation or pollution.

Furthermore, antioxidants slow down the onset of gray hair, which a study has shown to be correlated with the presence of free radicals. Indeed, although the mechanism by which these operate at the level of hair fibers remains poorly understood, it seems that free radicals could trigger a chain of reactions leading to the degradation of melanin, the pigment that gives hair its color.

Note : While the action of antioxidants in slowing down the appearance of white hair has been scientifically demonstrated, no study has been conducted on lemon verbena hydrosol itself. Therefore, we can only assume that this ingredient possesses this property, due to the antioxidants it contains.

If lemon verbena hydrosol is so widely used in perfumery, it's because of its pleasant and tangy scent, which instantly evokes the freshness of summer. Used as a spray or lotion on the hair, it provides a pleasant olfactory experience to your hair care routine. Moreover, its light and non-greasy texture leaves no residue on the hair and subtly scents them for the rest of the day. Thus, in addition to its various virtues mentioned above, lemon verbena floral water can be appreciated for its sensoriality.

• SEIBERG M. Age-induced hair greying - the multiple effects of oxidative stress. International Journal of Cosmetic Science (2013).

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