Mandelic Acid, Does This Active Ingredient Calm Acne?

It is milder than glycolic acid.

It is just as effective as glycolic acid or salicylic acid in treating acne.

It has anti-bacterial and anti-inflammatory properties in addition to its exfoliating action.

It is suitable for sensitive skin when used alone.

It can be combined with salicylic acid to enhance its acne-fighting effects.

Acne is an inflammatory disease of the pilosebaceous follicle. It is caused by multiple factors:

• Androgens (dihydrotestosterone), male hormones secreted by the testicles in males and by the adrenal glands and ovaries in females, cause the sebaceous glands to produce more sebum, which is responsible for facial seborrhea;

• The epidermis does not exfoliate as well as it should, which leads to an accumulation of dead cells on the surface of the skin that can clog the pores. In effect, this follicular hyperkeratosis forms a corneal plug that impedes the normal flow of sebum;

• A specific type of bacteria that lives in the pores, Cutibacterium acnes, formerly Propionibacterium acnes, feeds on sebum. However, when it is present in too large a quantity, it creates an oxygen-free environment conducive to their development and proliferation;

• The increase in bacteria causes inflammation, which the body detects and reacts by sending white blood cells to kill them. Specifically, these bacteria will secrete enzymes into the pilosebaceous follicle to hydrolyze the triglycerides in the sebum into irritating, proinflammatory free fatty acids, which are responsible for the formation of red pimples (papules).

Once the white blood cells have killed the bacteria, they die and leave behind pus, literally decaying white blood cells. Your body eventually absorbs this pus and the healing process begins.

There are different types of acne that can be classified as inflammatory or non-inflammatory.

• Non-inflammatory/retentional acne includes whiteheads and blackheads that form as a result of clogged pores. If the "plug" is exposed to air, it oxidizes and turns brown/black (blackhead), but if it is not exposed to air and is deep, it appears as a flesh-colored bump (whitehead).

• Inflammatory acne includes papules (red bumps), pustules (red pimples with white heads), nodules (larger, deeper bumps that may be red or purple) and cysts (larger, deeper red bumps filled with pus).

Mandelic acid is an alpha hydroxy acid (AHA), which is naturally found in bitter almonds. It acts as an exfoliant by breaking the chemical bonds that hold dead skin cells together so they can be removed from the skin's surface. It has a high molecular weight (MW = 152.14 g/mol), meaning that it penetrates the skin more slowly than other AHAs such as glycolic acid (MW = 76.05 g/mol) and lactic acid (MW = 90.08 g/mol).

Mandelic acid can benefit your skin in several ways, including in:

• Treatment of existing acne and prevention of new acne;

• Exfoliation of the skin;

• Stimulation of collagen production to improve the appearance of fine lines and wrinkles;

• Hydration of the skin;

• Reduction in the appearance of brown spots;

• Inhibition of bacterial proliferation;

• Reduction of inflammation.

As it is quite mild, mandelic acid must sometimes be combined with other AHAs (glycolic acid, lactic acid, tartaric acid...) or BHAs (salicylic acid) to increase its effectiveness. However, alone, it is an excellent option for sensitive skin.

Mandelic acid has been widely studied for the treatment of skin blemishes and skin conditions such as acne. It is indeed an excellent option for acne-prone skin, as it treats the four main causes of acne. It "controls" sebum secretion, inhibits bacterial growth, prevents pore clogging by increasing the skin's natural exfoliation process and reduces inflammation. In addition, compared to other AHAs and BHAs, it is less likely to cause skin irritation or post-inflammatory hyperpigmentation.

Anti-inflammatory, anti-bacterial, exfoliating... mandelic acid combines all the properties to act on pimples. A 2020 study even showed that a mandelic acid peel (45%) is just as effective as a salicylic acid peel (30%) in treating mild to moderate facial acne, while causing less irritation and side effects. Indeed, in Indian acne patients, the use of 45% mandelic acid peels once every two weeks for 12 weeks resulted in significant resolution of comedones, papules and pustules.

Another study also suggests the efficacy of 10% mandelic acid peels (+ 20% salicylic acid) in reducing non-inflamed and inflamed lesions when applied every two weeks for three months. In addition, they are also useful in nodular and cystic acne, and acne scars. Other research suggests that 5% mandelic acid is also just as effective in improving acne papules and pustules as 10% mandelic acid over an 8-week period. So you don't need a high concentration to get results.

How does mandelic acid work to improve acne? Still unknown, the exact mechanism of effect could be due to the modification of keratinization, and the anti-inflammatory and anti-bacterial activity of mandelic acid could also play a role in the improvement of acne. When you add up all of these benefits, mandelic acid could notably contribute to the prevention of pimples.

• TAYLOR M. B. Summary of mandelic acid for the improvement of skin conditions. Cosmetic Dermatology (1999).

• SARKAR R. & al. Glycolic acid peels versus salicylic–mandelic acid peels in active acne vulgaris and post-acne scarring and hyperpigmentation: a comparative study. Journal of American Society for Dermatologic Surgery (2008).

• SAHU P. & al. Comparative study of efficacy and safety of 45% mandelic acid versus 30% salicylic acid peels in mild‐to‐moderate acne vulgaris. Journal of Cosmetic Dermatology (2019).

• SWIERGIEL A. H. & al. Antimicrobial properties of mandelic acid, gallic acid and their derivatives. Mini-Reviews in Medicinal Chemistry (2021).