Retinoids, both naturally occurring and synthetic, are analogues of vi
tamin A. They represent a major advance in the treatment of acne and p
soriasis, as well as rarer conditions such as the ichthyoses. The more
frequent and widespread use of these drugs requires that the dermatol
ogist be aware of the wide spectrum of adverse events that may be enco
untered with their use. Some are serious and irreversible, such as ter
atogenicity, necessitating great care if these drugs are given to wome
n of childbearing potential. Other effects may be less severe, dose de
pendent and reversible. Although not devastating to the patient, appro
priate advice may reduce morbidity.