α-Hydroxy Acid (AHA)

Glycolic acid

  • Lactic acid

Weak organic acids

  • 1-20%
  • 20-70% for chemical peels
  • Cleansers, shampoos, lotion, cream, gel, solution, mask

1) Epidermal effects:

  • Decrease calcium in epidermis leading to corneodesmosomes degradation and desquamation, cell proliferation & delay keratinocyte differentiation
  • On follicular occlusion: comedolytic
  • High concentration: decrease melanin synthesis

2) Dermal effects (higher concentration):

  • Increase thickness due to fibroblast proliferation, increase collagen & glycosaminoglycans, improved quality of elastic fiber production

Xerosis; ichthyosis

  • Photoaging
  • Hyperpigmentation
  • Actinic keratosis
  • Acne vulgaris; rosacea
  • Psoriasis
  • Nail disorders
  • Chemical peels

  • Pregnancy Category B

Irritant contact dermatitis (most common): 

  • Decrease frequency or increase pH to decrease side effects
  • Hypo- & hyper- pigmentation (phototype IV-VI)
  • Photosensitivity
  • Herpes simplex virus infection: Very rare, can give prophylactic antiviral

  • Glycolic acid & lactic acid most commonly used
  • Others = large molecules that do not penetrate stratum corneum well (mandelic, tartaric, malic & citric acid)
  • Polyhydroxy acids (gluconolactone, galactose, lactobionic acid): similar mechanism of action to α-hydroxy acids but better humectants & moisturizer