What causes drug-induced skin pigmentation?
Several mechanisms may be involved in the drug-induced changes of pigmentation of the skin. • Certain heavy metals, e.g. iron, may be deposited in the dermis following damage to dermal vessels. If deposited in sufficient quantities a distinctive change in skin colour may be seen without any significant increase in melanin. • Some drugs react with melanin to form a drug-pigment complex. Exposure to sunlight often stimulates sun-induced melanin synthesis with formation of these complexes. • Some drugs will induce hypermelanosis (accumulation of melanin) as a non-specific post-inflammatory change in predisposed individuals. This is often worsened by sun exposure. • Some drugs induce pigmentation directly by accumulating and/or reacting with other substances in the skin.
