Background: Photonycholysis is a rare dermatological condition characterized by the detachment of the nail plate from the nail bed following ultraviolet (UV) light exposure. We herein report a rare case of photonycholysis induced by the combination of UV-A curing lamps and doxycycline therapy. Case Presentation: A 40-year-old woman developed painful onycholysis affecting all fingernails 5 days after using an acrylic gel cured under a 9-watt UV-A lamp. The patient had been on a three-week course of doxycycline for perioral dermatitis. Clinical examination revealed sharply demarcated, rounded onycholysis, sparing the lateral edges of the nail plates. The patient was advised to discontinue doxycycline, trim the affected nails, and apply topical methylprednisolone aceponate 0.1% cream. Full recovery was observed after 3 months. Discussion: Photonycholysis is an uncommon manifestation of drug-induced photosensitivity, particularly linked to tetracyclines such as doxycycline. UV-A exposure may exacerbates phototoxic reactions by generating reactive oxygen species, and damaging mitochondria in keratinocytes. Three distinct patterns of photonycholysis have been described, with type I, characterized by half-moon-shaped detachment, being most consistent with our case. Conclusion: This case underscores the importance of recognizing UV-curing lamps and photosensitizing drugs,such as doxycycline, as potential triggers for photonycholysis.