What you need to know about salicylic acid.

Thesalicylic acid is a type of beta-hydroxy acid (B.H.A.), known for its keratolytic action that promotes desquamation (the removal of dead skin cells). This molecule, derived from the plant world, was first extracted from willow bark in 1829 by a French pharmacist named Pierre-Joseph LEROUX. It is naturally present in several plants, particularly meadowsweet and willow, from which it gets its name. It is also found in many fruits and vegetables, including almonds, tomatoes, melons, raspberries, cherries, grapes, apricots, cucumbers, spinach, and so on. The famous aspirin is a synthetic derivative of salicylic acid: it's acetylsalicylic acid. It was first manufactured in 1853 by the chemist C.F. GERHARDT. In skincare, this active ingredient can be of synthetic or natural origin.

Several studies in vitro have demonstrated interesting properties of salicylic acid for the care of oily skin prone to all kinds of imperfections.

• Thanks to its antisepticproperties, it prevents the growth and proliferation of fungi, viruses, and bacteria, such as Cutibacterium acnes, a microorganism responsible for the inflammatory reactions of acne.

• It also exerts a keratolytic action and purifying effect. It promotes the removal of dead cells on the surface of the epidermis and stimulates cellular renewal. Thus, it is particularly effective in brightening dull complexions and restoring radiance to tired skin.

• Its soothing virtues help to reduce symptoms associated with inflammation. Salicylic acid plays a role in the arachidonic acid cascade and inhibits the synthesis of prostaglandins E2, molecules responsible for inflammatory and painful effects. In the treatment of acne, it thus soothes painful spots and visibly reduces redness.

• It boosts the synthesis of collagen and stimulates circulation, thus it is a superb active ingredient for diminishing signs of ageing. It notably helps to reduce the appearance of wrinkles and fine lines.

• Its properties sebum-regulating target the formation of comedones and prevent the pore obstruction that causes blackheads.

No, salicylic acid does not increase the skin's sensitivity to the sun. It can be applied in the morning, even if you plan to go out during the day. Just make sure to use a sunscreen every day, suitable for your skin tone.

Interestingly, salicylic acid can have a photo-protective effect on the skin! Two clinical studies have shown that salicylic acid, when applied a few minutes before UV exposure, reduces sunburn. However, it is important to emphasise that in these experiments, a relatively high concentration of salicylic acid was applied in large amounts shortly before UV exposure. It is absolutely not recommended to use salicylic acid as a sunscreen because to achieve efficient sun protection, you would need to use a concentration much higher than the 2% commonly used in cosmetics. This concentration would cause too much exfoliation and irritation for frequent use.

Salicylic acid is also present in many hair care products. It purifies the scalp and helps to eliminate any present flakes and dandruff. It is also used in the treatment of dull and brittle hair. It nourishes and protects the hair fibre. It provides shine and volume to the hair, making it silkier and easier to style. This active ingredient is also found in products for oily hair care, due to its action on sebaceous secretions.

Typology offers you two treatments concentrated in salicylic acid to take care of your skin and effectively combat imperfections:

• The local imperfections serum :

This serum, concentrated at 2% salicylic acid, effectively targets skin blemishes. It is also enriched with zinc (1%), a trace element that regulates sebum and has antimicrobial properties. It is applied locally, in small amounts. Generally, a single drop is sufficient for an isolated spot.The first results can be observed after three days.

• The Purifying Tonic :

Less concentrated in salicylic acid than the serum, this toner is more commonly applied over the entire face, as a daily routine, every evening, before one's night cream or botanical oil. Enriched with purifying and anti-bacterial agents, it brightens the complexion, tightens the pores and refines the skin texture.

• GARAVITO R.M & others. The structural foundation of aspirin's effectiveness deduced from the crystal structure of deactivated prostaglandin H2 synthase.Nature Structural Biology (1995).

• IL-HWAN KIM & co. Salicylic acid peels for the treatment of acne vulgaris in Asian patients. Dermatologic Surgery (2003).

• ARIF T. Salicylic acid as a peeling agent: a comprehensive review. Clinical, Cosmetic and Investigational Dermatology (2015).

• Kornhauser, A.et al.The impacts of topically applied glycolic acid and salicylic acid on ultraviolet radiation-induced redness, DNA damage and sunburn cell formation in human skin.J Dermatol Sci, (2009)

• Thomas Mammone & al., Salicylic acid shields the skin from UV harm, Journal of Cosmetic Science, (2006).

• Bubna, A. K. Revisiting Aspirin in Dermatology.Indian Dermatology Online Journal.<em>(2015)</em>