Furocoumarins are tricyclic compounds that can absorb UV-A light (320 to 400 nm). Psoralens are furocoumarin compounds used to treat vitiligo, psoriasis and a variety of other dermatologic conditions.
Furocoumarins occur naturally in many plants, including:
(1) celery
(2) figs
(3) caraway
(4) lemon
The burn is a partial-thickness burn like lesion resembling a second degree burn but sparing the dermis:
(1) erythema
(2) blistering
(3) diffuse epidermal necrosis with skin loss
A phototoxic reaction following exposure to sunlight and a plant containing a furocoumarin is called phytophotodermatitis (phyto = plant).
Severe reactions tend to occur when there is:
(1) diffuse exposure to a psoralen compound
(2) uncontrolled exposure to UV-A light, which can pass through regular glass
Prevention:
(1) Persons who handle psoralens or furocoumarins should wear gloves and protective clothing.
(2) Avoidance of suntan products containing psoralens or furocoumarins.
(3) Patients taking psoralens for a skin condition should have carefully controlled exposure to sunlight or UV-A light.
