Are there any contraindications to the use of mandelic acid?

Although derived from the seemingly harmless fruit and gentle due to its size compared to other AHAs, mandelic acid remains a fruit acid with episodes of side effects, although these are rare. It can be a source of redness, skin dryness, irritation, flaky skin, skin sensitive to touch, and inflammation. These side effects are more likely to occur if you start by using a high percentage of mandelic acid. However, it is generally well tolerated by all skin types.

Excessive use of mandelic acid can also lead to irritations and skin rashes due to over-exfoliation. It's also worth noting that mandelic acid is photosensitising, meaning it increases the skin's sensitivity to UV radiation, to which it is not usually sensitive, and causes an exaggerated skin reaction similar to a "sunburn" (painful skin redness sometimes accompanied by "blisters") under the influence of UV ray stimulation. The severity of the reaction depends on both the intensity of sun exposure, the applied concentration, as well as the individual's phototype. Therefore, certain precautions are necessary to protect against the risks of irritation and sensitisation.

Although it is a non-aggressive acid, the use of mandelic acid requires some precautions.

• Always perform a tolerance test before using skincare products containing mandelic acid for the first time. To do this, apply a small amount of the product to the inside of your elbow or behind your ear for two to three days and observe the area. If redness, tingling, swelling or itching occur, this indicates that you are not tolerating the product, and you should immediately cease its use. On the other hand, if no signs appear, it means that you are tolerating the product well.

• Limit any direct contact with the sun after application. Rigorously use a sunscreen with a high sun protection factor , SPF 30 or higher, every day to protect the skin from the harmful effects of the sun. Wear UV protective clothing (long clothes, hat). Indeed, used for its exfoliating properties, this agent can make the skin more sensitive to the sun. The reason? After exfoliation, the skin is thinner.

• Opt for treatments with a moderate concentration of mandelic acid, between 5 and 10%. The higher the percentage of mandelic acid in the peeling treatment, the greater the risk of side effects.

• Remember to properly hydrate your skin to limit signs of intolerance or choose a treatment containing anti-inflammatory and soothing active ingredients.

• Avoid combining it with other treatments enriched with fruit acids or retinoids, particularly for sensitive skin. Indeed, excessive use of chemical exfoliants can lead to over-exfoliation, which can cause skin sensitivity and breakouts.

• Avoid applying it on the lips or around the eyes, as it can cause irritation or damage. These areas are delicate due to their thinness.

• Never apply it after shaving, in case of a wound, sunburn, or on cracked or inflamed skin.

Carefully follow the instructions and take note of the warnings indicated on the label of the cosmetic product.

• Food & Drugs Administration (FDA). Alpha hydroxy acids (2022).

• PubChem. Mandelic acid.