What causes darkening of the fingernails?

Darkening of the fingernails can be caused by various factors, including trauma or injury to the nail bed, leading to bruising or subungual hematomas. It can also result from fungal infections, certain medical conditions like melanoma, or the use of specific medications. Additionally, exposure to certain chemicals or dyes may contribute to discoloration. If darkening occurs without an apparent cause, it’s advisable to consult a healthcare professional for evaluation.