Platinum agents are cornerstone therapies for many cancers but often cause neurotoxicity in post-mitotic tissues, for which effective interventions are lacking. This limitation reflects an incomplete understanding of neuronal responses to DNA damage. We show that nucleotide excision repair (NER) mediates cisplatin lesion removal in neurons; however, unlike its protective role in dividing cells, NER promotes neuronal death in response to cisplatin. This vulnerability arises because neurons possess low deoxynucleoside triphosphate (dNTP) pools. dNTPs are initially consumed during transcription-coupled NER to resolve transcription-blocking lesions. As dNTP levels become depleted, repair fails to complete, leading to accumulation of double-strand breaks, particularly during global-genome NER. Supplementation with deoxynucleosides or genetic upregulation of dNTP synthesis restores nucleotide pools, protects neurons from cell death, and reduces cisplatin-induced neuropathic pain. These findings identify limited dNTP availability as a key vulnerability in post-mitotic cells and suggest nucleoside supplementation as a potential strategy to mitigate chemotherapy-induced neurotoxicity.