Drug reactions affecting hair and nails.

Drug-induced changes of hair and nails have been observed with a variety of different pharmaceutical agents, both topical and systemic. These compounds or their metabolites may interfere with hair cycling and texture, nail matrix, nail bed, nail folds, and microvasculature. Phototoxic reactions may also occur. Before initiating treatment, physicians and patients should be aware of possible adverse events to hair and nails and should be aware of the preventive measures, if available, as quality of life can be reduced, and adherence and compliance to treatment may be impaired.