It is useful in acne because penetrates through follicles with comedolityc, sebostatic and bacteriostatic activity, and can be used also in active acne. - Salicylic acid: is a beta-hydroxy acid, soluble in alcohol. It has keratolityc action, removing the intercellular lipids, with diminished cohesion of corneocytes.
It is used at the concentration of 25-30% in alcoholic solution in moderate acne (comedonic and papulo-pustular) in active phase, in association with normal acne therapy with good results. The evaporation of alcohol inactivates the salicylic acid, without risk of overdose. It has been used also in hyper pigmentation and cloasma, with moderate results. After application there is a light transient eritema and a fine desquamation for few days. -Lactic acid: is used at the concentration of 92% in melasma with good results.

2) MEDIUM PEELING: - Pyruvic Acid: is an alfa-chetoacid in solution with lactic acid and it is used at the concentration of 50-70%. Good results have been obtained in papulo-pustular and cystic acne, also in the rosaceiform type, with decrease of the inflamed lesions and also in late sequellae of acne, in hyperseborrea, photo-aging and hyperpigmentation.
This substance thins the epidermis with exfoliation (until the upper reticular layer) and stimulates the dermis to produce new collagen and elastic fibres. The penetration through follicles justifies the action in acne, with sebostatic, anti-inflammatory and bacteriostatic effect. After application on skin a “frosting” appears, indicating the penetration in the papillary dermis, the application of water interrupts the effect. -Tricloroacetic acid (TCA): until the concentration of 30% penetrates in the reticular dermis, stimulating the neosynthesis of collagene and elastin. It is used in the sequellae of acne and in hyperpigmentation and cloasma. It is necessary to select the patients, avoiding dark photo types (type IV and V°), preferring fair photo types with thin epidermis.

3) STRONG PEELING: because they arrive at the reticular dermis, they must be used by skilled dermatologists, in fact they can cause necrosis of epidermis, with possible formation of scars.