Mandelic Acid

Mandelic Acid is an alpha hydroxy acid (AHA) extracted from bitter almond. It has a long, safe history of use in medicine as an oral antibiotic, but has only recently become popular in skincare. Its use in skincare was pioneered by Dr Fulton, one of the researchers who developed Retin-A. In his view mandelic acid is the best skin active to come along since Retin-A.

Mandelic acid is an appropriate treatment for a wide variety of skin concerns, from acne to wrinkles; it is especially good in the treatment of adult acne as it addresses both of these concerns. One of the advantages of Mandelic Acid is that it is safer to use on darkly pigmented skin than glycolic acid or tretinoin. 5% to 10% glycolic acid and tretinoin can trigger hyperpigmentation in darkly pigmented skin.

Mandelic acid has excellent results in the treatment of acne. It can improve inflammatory pustular, comedonal, and papular acne and has been shown to be effective even in individuals resistant to antibiotics (systemic and/or topical). Results can be visible within days of starting a mandelic acid skincare regime.

cross section of damaged skin
cross section of damaged skin

Extensive trials show that as well as treating acne, mandelic acid has other significant long term benefits for the skin. The diagram on the left shows some typical issues seen in damaged skin that mandelic acid products may improve.

Individuals using Mandelic acid characteristically report the following benefits:


Typically use of mandelic acid products results in a steady, gradual improvement in abnormal pigmentation over a period of months. Improvements have been recorded in melasma (including dermal melasma), postinflammatory hyperpigmentation, and lentigines (age spots). Use of mandelic acid products can increase the effectiveness of other pigment correcting treatments.

Fine wrinkles and lines.

As with glycolic acid, skin texture visibly improves within days or weeks. This effect continues over months and years of treatment resulting in a long-term improvement in fine lines and wrinkles.

cross section of healthy skin
Cross section of healthy skin


Mandelic acid is unique because it has a natural antibiotic action. No other Alpha Hydroxy Acid has this.


As well as being antibacterial, Mandelic acid works by breaking up the bond between dead skin cells, leading to an increased rate of cellular turnover.

This is beneficial because it purges the skin of damaged skin cells, which can lead to wrinkles, hyperpigmentation and acne, among other conditions. The result is skin that is more flexible, smoother, and more even in tone.

The diagram on the right illustrates the functions of healthy skin that mandelic acid products can help support.

Mandelic acid has a larger molecular structure than glycolic acid and this makes it better tolerated on the skin. Despite being less irritatiing, mandelic acid is in fact stronger than glycolic acid, having a pK of 3.41. In comparison, glycolic acid has a pK of 3.83 (the lower the pK value, the stronger the acid). Mandelic acid belongs to a sub-group of AHAs known as aromatic alpha hydroxy acids, and is the smallest aromatic AHA.