Can other drugs cause increased skin pigmentation?

Yes. Arsenicals, busulfan, 5-fluorouracil, cyclophosphamide, topical nitrogen mustard (mechlorethamine), and bleomycin most commonly cause increased skin pigmentation. The mechanisms by which these drugs cause hyperpigmentation are unknown, but it is possible that the drug or a metabolite either directly stimulates epidermal melanocytes to increase melanin synthesis or indirectly stimulates metabolic pathways that cause increased epidermal melanization.

Litt J, editor: Litt’s drug eruption reference manual, ed 15, New York, 2009, Informa Healthcare.