Drug-induced nail toxicity is defined as nail manifestations triggered by medications, administered systemically, topically, or intralesionally [1]. These changes commonly involve multiple nails and align with the timing of drug intake [2]. They may affect any part of the nail unit, including the nail matrix, nail bed, nail plate, and/or periungual tissues [3, 4]. Additionally, drug deposition at the dermal level may contribute to nail plate pigmentation, often coinciding with skin or mucous membrane pigmentation [4]. While chemotherapeutic agent nail toxicities (discussed in Chap. 48 ) have been well documented, non-chemotherapeutic agent-induced nail toxicities are likely underreported, and literature is mainly limited to case reports and case series. These nail changes may cause cosmetic concerns, discomfort, or functional limitations [3]. In this chapter, we review non-chemotherapy-induced nail changes.