phytophotodermatose

Phytophotodermatosis is a phototoxic skin reaction that occurs after contact with certain plant-derived substances and subsequent exposure to ultraviolet A (UVA) radiation. It results from furocoumarins, also known as psoralens, in plants and plant juices that become active under UVA light, causing inflammation of sun-exposed skin.

Common sources include citrus fruits such as limes and bergamot, as well as celery, parsley, parsnip, dill, figs, rue and other plants. Contact with sap or juice, especially on arms or hands, followed by sun exposure, typically triggers the reaction. A related condition, Berloque dermatitis, can occur after exposure to bergamot oil found in some perfumes.

Pathophysiology involves UVA-induced activation of furocoumarins, which interact with skin DNA and cellular components, leading to cell damage, inflammation and a robust sunburn-like response. The lesions often appear where the skin was in contact with the plant or juice and can show linear or streaked patterns corresponding to drips or contact lines. Hyperpigmentation may persist for weeks to months after the acute phase.

Clinically, patients develop erythema, swelling and sometimes vesicles or blisters within 24–72 hours of exposure. Blistered areas may heal with residual hyperpigmentation. Diagnosis is usually clinical, supported by a history of plant contact and sun exposure; photopatch testing is rarely needed.

Treatment focuses on removing the offending agent, protecting the skin from further UVA exposure, and symptomatic care. This includes gentle cleansing, cool compresses, topical corticosteroids for inflammation, analgesics, and sunscreen. Most cases resolve in 1–3 weeks, though pigmentation may last longer. Prevention emphasizes protective clothing, prompt washing of skin after plant contact, and avoiding sun exposure after contact.