ABSTRACT
General remarks Since the 1980s, alpha-hydroxy acids (AHAs) have been used alone or in combination with other acids with a view to achieving good cosmetic results, locally or generally, temporarily or permanently, and without running the risks of deeper peels. The natural origins of the first AHAs – fruit or dairy extracts – account for much of their resounding success. How could anyone resist such a benign-sounding name as ‘fruit acids’? The AHA most often used is without doubt glycolic acid, a small molecule with a low molecular weight that has no difficulty penetrating the stratum corneum, where it acts as a ‘corneodesmosome chainsaw’. It was for this property that it was first indicated in the treatment of ichthyosis and other disorders involving hyperkeratinization. An AHA applied to a clean and degreased skin breaks down the protein structures that form corneodesmosomes. The superficial cell layers are then shed from the epidermis. The skin immediately feels more hydrated, as the fingers no longer touch the dead and dehydrated corneocytes that have been shed but rather living and well-hydrated keratinocytes. AHAs are not toxic to melanocytes, and can therefore be applied on all skin types. They can also be used at any time of the year, on condition that they are combined with a strong sunscreen. AHA peels have other advantages as well: they are non-toxic and hypoallergenic, do not cause protein coagulation, have an excellent safety record, are easy to use and produce satisfactory results in a variety of indications.
